Carbohydrates

148. Which of the following defines the term "glycolysis"? A. Conversion of glucose into lactate or pyruvate B. Conversion of glucose to glycogen C. Breakdown of glycogen to form glucose D. Breakdown of lipids to form glucose

...A. Conversion of glucose into lactate or pyruvate

146. In what form is glucose stored in muscle and liver? A. Glycogen B. Maltose C. Lactose D. Starch

...A. Glycogen

147. Which of the following carbohydrates is a polysaccharide? A. Starch B. Sucrose C. Lactose D. Glucose

...A. There are three major classifications of carbohydrates: monosaccharides, disaccharides, and polysaccharides. Starch is classified as a polysaccharide because its structure is composed of many molecules of glucose (a monosaccharide) condensed together. Monosaccharides (e.g., glucose) are carbohydrates with the general molecular formula UbO), that cannot be broken down to simpler substances by acid hydrolysis. Disaccharides (e.g., sucrose, lactose) are condensation products of two molecules of monosaccharides with loss of one molecule of water.

149. What is the glucose concentration in fasting whole blood? A. Less than the concentration in plasma or serum B. Greater than the concentration in plasma or serum C. Equal to the concentration in plasma or serum D. Meaningless because it is not stable

...A. When highly specific analytical methods are used, the glucose concentration in fasting whole blood is approximately 12-15% lower than in plasma or serum. Although glucose diffuses freely between the water phase of plasma and red blood cells, there is a higher concentration of water in plasma (approximately 12%) than in whole blood, accounting for the increased glucose concentration in plasma. The water content of whole blood depends on the hematocrit.

165. Which of the following is not a reagent required in an enzymatic serum glucose method? A. NAD+ B. Glucose oxidase C. Peroxidase D. Reduced chromogen

.A. The glucose oxidase method for quantifying glucose employs two coupled enzymatic reactions. In the first reaction, which is catalyzed by glucose oxidase, glucose in the presence of oxygen is oxidized to gluconic acid and hydrogen peroxide. In the second reaction, peroxidase catalyzes a reaction between hydrogen peroxide and the reduced form of a chromogenic oxygen acceptor, such as o-dianisidine, forming an oxidized colored product that is read spectrophotometrically. ..

153. A 30-year-old pregnant woman has a gestational diabetes mellitus screening test performed at 26 weeks of gestation. Her physician chooses to order a 50-g oral glucose load. Her serum glucose level is 150 mg/dL at 1 hour. What should occur next? A. This confirms diabetes mellitus; give insulin. B. This confirms diabetes mellitus; dietary intake of carbohydrates should be lessened. C. This is suspicious of diabetes mellitus; an oral glucose tolerance test should be performed. D. This is an expected glucose level in a pregnant woman.

.C. Increased insulin resistance is commonly seen in the late second and third trimesters of pregnancy. Most women are able to compensate by secreting additional insulin and, thus, are able to maintain normal blood glucose levels. In cases of gestational diabetes mellitus, women are unable to make sufficient insulin to meet their needs. In the screening test, serum glucose is assessed at 1 hour following the ingestion of a 50-gram glucose load (glucose challenge test). If the serum glucose is >140 mg/dL, the next step is to perform an oral glucose tolerance test...

0. Which of the following findings is characteristic of all forms of clinical hypoglycemia? A. A fasting blood glucose value below 55 mg/dL B. High fasting insulin levels C. Neuroglycopenic symptoms at the time of low blood sugar D. Decreased serum C peptide

.C. Neuroglycopenic symptoms at the time of low blood sugar

Impaired fasting glucose (IFG)

100-125 mg/dL

Renal Threshold for Glucose

160-180mg/dl

What is the normal range of CSF glucose?

40-70 mg/dl CSF glucose is 2/3 of the plasma glucose which is due to the glucose entering the CSF by facilitative transport

Cori, type III:

: Amylo-1,6-glucosidase deficiency

Glucagon

A protein hormone secreted by Alpha cells of islets of langerhans, pancreatic endocrine cells that raises blood glucose levels by breaking down glycogen to glucose, therefore it is an antagonistic hormone to insulin. Stimulates glycogenolysis. (breakdown of glycogen into glucose)

What is the American Diabetes Association recommended cutoff value for adequate control of blood glucose in diabetics as measured by glycated hemoglobin? A. 5% B. 6.5% C. 9.5% D. 11%

B The ADA recommends that 6.5% be used as the cutoff for determining the adequacy of treatment for diabetes. A glycated hemoglobin test should be performed at the time of diagnosis and every 6 months thereafter if the result is < 6.5%. If the result is 6.5% or more, the treatment plan should be adjusted to achieve a lower level, and the test performed every 3 months until control is improved.

What decreases in diabetes

Bicarbonate Blood pH

What increases in diabetes

Blood glucose Urine glucose Urine specific gravity Glycohemoglobin Ketones (blood & urine) Anion gap BUN Osmolality (serum & urine) Cholesterol Triglycerides

Hyperglycemic

Blood glucose level >100mg/dl

9. Which statement regarding gestational diabetes mellitus (GDM) is correct? A. Is diagnosed using the same oral glucose tolerance criteria as in nonpregnancy B. Converts to diabetes mellitus after pregnancy in 60%-75% of cases C. Presents no increased health risk to the fetus D. Is defined as glucose intolerance originating during pregnancy

D Control of GDM reduces perinatal complications such as respiratory distress syndrome, high birth weight, and neonatal jaundice. Women at risk are usually screened between 24 and 28 weeks' gestation. The screening test can be performed nonfasting and consists of an oral 50-g glucose challenge followed by serum or plasma glucose measurement at 1 hour. A result ≥ 140 mg/dL is followed by a 2-hour or 3-hour oral glucose tolerance test to confirm gestational diabetes. For the 3-hour test, a 100-g dose of glucose is used and at least two of the following cutoffs must be exceeded: fasting, ≥ 95 mg/dL or higher; 1 hour, ≥ 180 mg/dL or higher; 2 hour ≥ 155 mg/dL or higher; 3 hour, ≥ 140 mg/dL or higher. The same cut points are used for the 2-hour test except that a 75-g dose is used. GDM converts to diabetes mellitus within 10 years in 30%-40% of cases. ADA recommends testing persons with GDM for diabetes 6-12 weeks after delivery

What does hydrolysis of sucrose yield? A. Glucose only B. Galactose and glucose C. Maltose and glucose D. Fructose and glucose

D When sucrose is hydrolyzed it forms a 1:1 mixture of glucose and fructose.

Oral glucose tolerance test Done how glucose load is Values at 2 hours normal, impaired and diabetic

Fasting. Draw blood initially to get a baseline, then drink 75 g glucose. blood measured after 2 hrs Normal 2hr post load glucose should be less than 140 mg/dl Impaired post load 2hr glucose is between 140- 199mg/dl Diabetic post load glucose is 200 or more mg/dl (provisional, has to be confirmed)

Hypoglycemic

Glucose level <50mg/dl

How is Plasma Glucose measured?

Glucose oxidase method Hexokinase method

Growth hormone and adrenocorticotropic hormone (ACTH):

Hormones secreted by the anterior pituitary that raise blood glucose levels

Thyroxine

Increases absorption of glucose from the intestines. Stimulates glycogenolysis.

Hormones affecting glucose

Insulin : Lowers glucose, stimulates glucose uptake by cells Glucagon, increases glucose, stimulates, glycogenesis (breakdown of glycogen to glucose) ACTH, : Increases glucose, insulin antagonist Growth hormone: Increases glucose, insulin antagonist Cortisol: Increases glucose, Stimulates gluconeogenesis. Human placental lactogen: Increases glucose, insulin antagonist. Epinephrine: increases glucose, stimulates glycogenolysis. T4, T3 : Increases glucose, stimulates glycogenolysis Somatostatin: secreted from delta cells of pancreas, inhibits glucagon and insulin.

Type 1 diabetes mellitus Characterized by? Usually caused by? Peak incidence?

Insulinopenia. Individuals require insulin treatment Autoimmune destruction of beta cells of islets of langerhans Peak incidence : childhood and adolescence but can happen at any age.

Test methodology for lactate

Lactate + O2 --- lactate oxidase... pyruvate + H2O2 H2O2 + reduced chromogen --peroxidase---- oxidized chromogen (colored) + H2O

Glycated/glycosylated hemoglobin measured by

Measured by affinity chromatography, ion-exchange chromatography, and high-performance liquid chromatography range 4-6 % effective treatment range <7% Hb Alc

Specimen collection: A1c

Nonfasting blood drawn in EDTA tubes

Somatostatin

Synthesized by delta cells of the pancreatic islets of Langerhans; inhibits secretion of insulin, glucagon, and growth hormone, resulting in an increase in plasma glucose level

Gluconeogenesis

The formation of glucose from noncarbohydrate sources, such as amino acids glycerol, or lactate that occurs during long-term fasting

Under what conditions is lactate produced in the body?

The normal end product of glucose metabolism is pyruvate; however, lactate is produced under conditions of oxygen deficit (anaerobic metabolism). The production and accumulation of lactate in the blood and its measurement aid in assessing the degree of oxygen deprivation that is occurring Change in the blood lactate level precedes a change in blood pH. Lactate is metabolized by the liver via gluconeogenesis.

Pompe, type II:

a-1,4-glucosidase deficiency

Insulin: where is it produced? It promotes________ It inhibits_________

beta cells in the islets of langerhans. promotes the entry of glucose into liver, muscle, and adipose tissue to be stored as glycogen and fat; inhibits the release of glucose from the liver It encourages uptake of glucose into cells

fructosamine test methodology

spectrophotometric/colorimetric methods, affinity chromatography, and high-performance liquid chromatography d. Reference range: 205-285 |xmol/L

Why are D-xylose tolerance tests performed?

to differentiate malabsorption from pancreatic insufficiency.

When are random plasma glucose samples are collected? Value which indicates abnormality?

≥ 200 mg/dL Any time, needs no preparation Done for patients with hyperglycemia

169. What is the reference interval for fasting serum glucose in an adult expressed in SI units (International System of Units)? A. 1.7-3.3 mmol/L B. 3.3-5.6 mmol/L C. 4.1-5.5 mmol/L D. 6.7-8.3 mmol/L

...C. The reference interval for fasting serum glucose in an adult expressed in conventional units is 74-99 mg/dL. To convert conventional units to SI units (Systeme International d'Unites), multiply the conventional units in mg/dL by the 0.0555 conversion factor to obtain SI units in mmol/L. Thus, 74 mg/dL x 0.0555 = 4.1 mmol/L and 99 mg/dL x 0.0555 = 5.5 mmol/L. Although conventional units are used commonly in the United States, many scientific journals require the use of SI units in their publications and many foreign countries use SI units routinely in clinical practice. To identify additional conversion factors for other analytes, consult the appendix of a clinical chemistry textbook.

159. Which of the following statements applies to the preferred use of plasma or serum, rather than whole blood, for glucose determination? A. Glucose is more stable in separated plasma or serum. B. Specificity for glucose is higher with most methods when plasma or serum is used. C. It is convenient to use serum or plasma with automated instruments because whole blood requires mixing immediately before sampling. D. All the above.

...D. Glucose determinations are generally performed on serum or plasma rather than whole blood. Serum or plasma is more convenient to use than whole blood in most automated systems because serum does not require mixing before sampling. Glucose stability is greater in separated plasma than in whole blood because glycolysis is minimized. Specificity for glucose is higher when plasma or serum is used because variations attributable to interfering substances in the red cells are avoided.

171. Which of the following hormones does not promote an increase in blood glucose levels? A. Growth hormone B. Cortisol C. Glucagon D. Insulin

...D. Insulin

178. Which of the following is characterized by a deficiency of glucose-6-phosphatase resulting in hepatomegaly, lactic acidosis, and severe fasting hypoglycemia? A. Type I—von Gierke disease B. Type II—Pompe disease C. Type III—Cori disease D. Type IV—Andersen disease

..A. .• Type I—von Gierke disease is clinically characterized by severe fasting hypoglycemia and lactic acidosis. This is due to a deficiency of the enzyme glucose-6-phosphatase. Glucose cannot be transported from the liver as glucose-6-phosphate during the breakdown of glycogen. It is metabolized to lactic acid and thus results in lactic acidosis. • Type II—Pompe disease is caused by a deficiency of lysosomal a-l,4-glucosidase. This results in an increase of glycogen in all organs and abnormally large lysosomes. The glycogen cannot be degraded because of the deficiency of a-1,4-glucosidase. • Type III—Cori disease is caused by the absence of a debrancher enzyme. This disease is characterized by hypoglycemia, hepatomegaly, seizures, and growth retardation. • Type IV—Andersen disease is caused by a deficiency of brancher enzyme. It is a rare disease characterized by progressive liver enlargement or cirrhosis and muscular weakness by the age of 2 months. Storage glycogen is not usually found, but unbranched amylopectin accumulates in this disease

168. An individual has a plasma glucose level of 110 mg/dL. What would be the approximate glucose concentration in this patient's cerebrospinal fluid? A. 33 mg/dL B. 55 mg/dL C. 66 mg/dL D. 110 mg/dL

..C. The reference interval for glucose in CSF is 60% of the normal plasma value. For a plasma glucose of 110 mg/dL, the expected CSF glucose level would be 66 mg/dL. The equilibration of CSF with plasma glucose takes several hours. The reference interval for the CSF glucose level is 40-70 mg/dL as compared with a normal fasting plasma glucose level. Low levels of CSF glucose are associated with a number of diseases including bacterial meningitis and tuberculous meningitis, whereas viral disease generally presents with a normal level of CSF glucose..

151. Which test may be performed to assess the average plasma glucose level that an individual maintained during a previous 2- to 3-month period? A. Plasma glucose B. Two-hour postprandial glucose C. Oral glucose tolerance D. Glycated hemoglobin

..D. Glycated hemoglobin

160. Which of the following analytes would not commonly be measured when monitoring complications of diabetes mellitus? A. Serum urea nitrogen B. Urinary albumin C. Serum creatinine D. Serum bilirubin

..D. Research has demonstrated that there is a correlation between blood glucose levels in diabetes mellitus and the development of long term complications. These complications may include such disorders as retinopathy, neuropathy, atherosclerosis, and renal failure. Thus, quantifying such blood analytes as urea, creatinine, and lipids as well as urinary albumin can aid in monitoring diabetic individuals..

173. What would an individual with Cushing syndrome tend to exhibit? A. Hyperglycemia B. Hypoglycemia C. Normal blood glucose level D. Decreased 2-hour postprandial glucose

.A. In Cushing syndrome the adrenal cortex secretes an excessive amount of the hormone cortisol. Because cortisol has a stimulatory effect on gluconeogenesis, hyperglycemia commonly occurs as a secondary disorder. Hypoglycemia frequently characterizes Addison disease in which there is decreased production of cortisol.

176. A patient has a urine uric acid level of 1575 mg/day. What effect will this have on the measured urine glucose level when the glucose oxidase/peroxidase method is employed? A. Urine glucose level will be falsely low. B. Urine glucose level will be falsely high. C. Urine glucose level will be accurate. D. Urine glucose level will exceed the linearity of the method.

.A. In the glucose oxidase/peroxidase method, the second coupled enzyme reaction involves peroxidase catalyzing the reaction between hydrogen peroxide and a chromogenic oxygen acceptor, which is oxidized to its colored form. Several blood constituents, including uric acid, ascorbic acid, bilirubin, tetracycline, hemoglobin, and glutathione, when present in increased concentrations can interfere with the assay by competing for the hydrogen peroxide produced in the first coupled enzyme reaction. This loss of hydrogen peroxide would result in falsely low plasma glucose results. Because of the high levels of uric acid normally found in urine, the glucose oxidase/peroxidase method would not be suitable for measuring urine glucose...

175. A cerebrospinal fluid specimen is sent to the lab at 9:00 P.M. for glucose analysis. The specimen is cloudy and appears to contain red blood cells. Which of the following statements is true? A. Glucose testing cannot be performed on the specimen. B. Specimen should be centrifuged and glucose assayed immediately. C. Specimen can be refrigerated as received and glucose assayed the next day. D. Specimen can be frozen as received and glucose assayed the next day

.B. Because of the critical reasons for aspirating a CSF specimen, the testing is performed as soon as possible upon receipt of the specimen in the laboratory. In this case, the cloudy appearance would be most likely due to the presence of bacteria. Both bacteria and red blood cells can use glucose in vitro. Thus any delay in glucose testing could result in a falsely low result. The CSF specimen should be centrifuged to remove cellular material and assayed immediately..

163. Which glucose method can employ a polarographic oxygen electrode? A. Hexokinase B. Glucose oxidase C. Glucose dehydrogenase D. o-Toluidine

.B. Glucose in the presence of oxygen is oxidized to gluconic acid and hydrogen peroxide. This reaction is catalyzed by glucose oxidase. By using a polarographic oxygen electrode, the rate of oxygen consumption is measured and related to the concentration of glucose in the sample..

172. What effect if any would be expected when the secretion of epinephrine is stimulated by physical or emotional stress? A. Decreased blood glucose level B. Increased blood glucose level C. Increased glycogen storage D. No effect on blood glucose or glycogen levels

.B. Increased blood glucose level Epinephrine is produced by the adrenal medulla. It promotes glycogenolysis, thus increasing the blood glucose level. Epinephrine also inhibits the secretion of insulin and stimulates the secretion of glucagon

152. The physician determined that the patient needed an oral glucose tolerance test (OGTT) to assist in diagnosis. The patient had blood drawn for the OGTT, and the following serum glucose results were obtained. These results are indicative of what state? Fasting serum glucose 124 mg/dL 2-hour postload serum glucose 227 mg/dL A. Normal B. Diabetes mellitus C. Addison disease D. Hyperinsulinism

.B. The patient presents as having diabetes mellitus. The American Diabetes Association (ADA) published updated standards in 2007 for the classification and diagnosis of diabetes mellitus. Three criteria have been defined, with only one needing to be present to establish the diagnosis of diabetes rnellitus. The three criteria include classic diabetic symptoms and a casual plasma glucose of >200 mg/dL, a fasting plasma glucose of >126 mg/dL, and a 2-hour postload plasma glucose (part of OGTT) of >200 mg/dL. It is recommended that any positive test be repeated on a subsequent day, if possible, to confirm the diagnosis. It should be noted that the OGTT is not recommended for routine clinical use and would be used only in special circumstance

174. As part of a routine physical, a fasting plasma glucose is performed on a 45-yearold male and the test result is 105 mg/dL. How should this individual be classified? A. Normal for his age B. Impaired fasting glucose C. Type 1 diabetes mellitus D. Type 2 diabetes mellitus

.B. When a fasting plasma glucose test is performed and the glucose value is between 100-125 mg/dL, the individual is considered to have impaired fasting glucose (IFG). This is less than the value associated with diagnosis of diabetes mellitus, which is a fasting plasma glucose > 126 mg/dL. IFG is considered a risk factor and a stage between normal glucose metabolism and development of diabetes mellitus...

167. Which glucose method is considered to be the reference method? A. Glucose oxidase B. o-Toluidine C. Hexokinase D. Glucose dehydrogenase

.C. Although there are several reliable enzymatic glucose methods available, the hexokinase method is the reference method for quantifying glucose. The reference method requires that a protein-free filtrate be made using barium hydroxide and zinc sulfate. The clear supernatant is then used as the sample in the hexokinase/glucose-6-phosphate dehydrogenase coupled enzyme reactions. For routine clinical use, serum is used directly in the hexokinase method because deproteinization is too time-consuming...

64. Which glucose method catalyzes the phosphorylation of glucose by adenosine triphosphate, forming glucose-6- phosphate and adenosine diphosphate with the absorbance of the NADPH product read at 340 nm? A. o-Toluidine B. Glucose oxidase C. Hexokinase D. Glucose dehydrogenase

.C. The hexokinase method for quantifying glucose uses two coupled enzymatic reactions. In the first reaction, which is catalyzed by hexokinase, glucose is phosphorylated by adenosine triphosphate, forming glucose-6-phosphate and adenosine diphosphate. In the second reaction, glucose-6-phosphate dehydrogenase (derived from yeast) catalyzes the oxidation of glucose-6- phosphate and the reduction of nicotinamide adenine dinucleotide phosphate. The amount of reduced NADPH formed is proportional to the glucose concentration in the sample. Thus, the greater the absorbance reading of NADPH at 340 nm, the greater is the glucose concentration. If bacterial G-6-PD is used, the cofactor is NAD+ with the production of NADH..

177. Laboratory tests are performed on a postmenopausal, 57-year-old female as part of an annual physical examination. The patient's casual plasma glucose is 220 mg/dL, and the glycated hemoglobin (Hb AIC) is 11%. Based on this information, how should the patient be classified? A. Normal glucose tolerance B. Impaired glucose tolerance C. Gestational diabetes mellitus D. Type 2 diabetes mellitus

.D. A casual plasma glucose should be less than 200 mg/dL. The reference range for glycated hemoglobin (Hb Alc) is 4-6%. Because the individual is a postmenopausal, 57-year-old female, with abnormal test results being found as part of an annual physical examination, the most likely diagnosis is type 2 diabetes mellitus. The ADA recommends that in the absence of unequivocal hyperglycemia, the glucose result should be confirmed by repeating the casual glucose or performing a fasting plasma glucose on a subsequent day. The ADA does not recommend Hb Alc as a screening test for diabetes mellitus...

155. Which of the following does not properly describe type 1 diabetes mellitus? A. Insulin deficiency B. Associated with autoimmune destruction of pancreatic Beta cells C. Ketoacidosis prone D. Occurs more frequently in adults

.D. Based on the biochemistry of the disease, diabetes mellitus has been classified as type 1 and type 2. Type 1 occurs more commonly in individuals under 20 years of age. Studies suggest that type 1 is associated with autoimmune destruction of (3-cells, and it is characterized by insulin deficiency and thus a dependency on injection of insulin. Unlike people afflicted with type 2, type 1 individuals are prone to ketoacidosis and to such complications as angiopathy, cataracts, nephropathy, and neuropathy..

158. Which of the following is not characteristic of severe hyperglycemia? A. Polyuria B. Ketonuria C. Glycosuria D. Hypoglucagonemia

.D. In uncontrolled diabetes mellitus, the blood glucose level exceeds the renal threshold of approximately 180 mg/dL for glucose, leading to glycosuria and polyuria. The excess secretion of glucagon stimulates lipolysis, with increased formation of acetoacetic acid. In the blood, the keto acids dissociate, with the hydrogen ions being buffered by bicarbonate. This causes the bicarbonate to become depleted and leads to metabolic acidosis..

154. A sample of blood is collected for glucose in a sodium fluoride tube before the patient has had breakfast. The physician calls 2 hours later and requests that determination of blood urea nitrogen (BUN) be performed on the same sample rather than obtaining another specimen. The automated analyzer in your laboratory utilizes the urease method to quantify BUN. What should you tell the physician? A. Will gladly do the test if sufficient specimen remains B. Could do the test using a micromethod C. Can do the BUN determination on the automated analyzer D. Cannot perform the procedure

.D. Sodium fluoride is a weak anticoagulant that acts as a preservative for glucose. It functions as a glucose preservative by inhibiting glycolysis. However, it is not suitable for use with many enzyme procedures. In the determination of BUN, where urease activity is utilized, the high concentration of fluoride in the plasma acts as an enzyme inhibitor, preventing the necessary chemical reaction...

161. Ingestion of which of the following drugs may cause hypoglycemia? A. Ethanol B. Propranolol C. Salicylate D. All the above

.D. There are greater than 100 causes of hypoglycemia. Among the causes is the ingestion of certain drugs. Use of ethanol, propranolol, and salicylate has been linked to the occurrence of hypoglycemia...

What casual plasma glucose levels will indicate diabetes? Plasma glucose value of____________ at 2hrs point of OGTT described by WHO indicates diabetes. Fasting plasma glucose value?

1)An individual expressing physical symptoms and a casual plasma glucose level of >200 mg/dL 2) Plasma glucose level of >200 mg/dL at 2-hour point of an OGTT as described by the World Health Organization (WHO) 3) 2) Fasting plasma glucose level that is >126 mg/dL (fasting defined as no caloric intake for minimum of 8 hours)

Gestational diabetes OGTT Glucose load Impaired plasma glucose Diabetes

100 mg/ml Results must meet or exceed two or more of these criteria fasting plasma glucose >95mg/dl 1 hr plasma glucose > 180 mg/dl 3 hr > 140 mg/dl or alternately a 75 g post load glucose may be used and is the same as that for non pregnant patients Fasting plasma glucose is collected 10 mins before post load and 120 mins after post load. Urine may also be used sometimes Impaired plasma glucose > or equal to 126 mg/dl at fasting and between 140-199 mg/dl at 2 hrs Diabetes is >126 fasting and >200mg/dl at 2 hrs

In Gestational diabetes mellitus (GDM) diagnosis what is the fasting glucose value? What is the casual glucose value?

126 mg/dl or greater 200mg/dl or greater if unequivocal hyperglycemia is not present testing should be done on a subsequent day

2. Which of the following hormones promotes hyperglycemia? A. Calcitonin B. Growth hormone C. Aldosterone D. Renin

2. B Growth hormone and cortisol promote gluconeogenesis and epinephrine stimulates glycogenolysis. Excess thyroid hormone causes hyperglycemia by increasing glucagon and inactivation of insulin, thereby promoting both gluconeogenesis and glycogenolysis. An increase in any of these hormones can cause hyperglycemia. Calcitonin opposes the action of parathyroid hormone. Aldosterone is the primary mineralocorticoid hormone and stimulates sodium reabsorption and potassium secretion by the kidneys. Renin is released from the kidney due to ineffective arterial pressure and promotes activation of angiotensinogen and aldosterone secretion.

. Select the enzyme that is most specific for β-D-glucose. A. Hexokinase B. G-6-PD C. Phosphohexisomerase D. Glucose oxidase

4. D Glucose oxidase is the most specific enzyme reacting with only β-D-glucose. However, the peroxidase coupling reaction used in the glucose oxidase method is subject to positive and negative interference. Therefore, hexokinase is used in the reference method.

gestational diabetes Post load quantity for glucose challenge glucose is tested when what is the value

50 g oral glucose load (fasting not needed) Blood is drawn after 1 hr plasma is tested If value is > or equal to 140 mg /dl then a three hour OGTT is done

9. In addition to measuring blood glucose, Hgb A1c, and microalbumin, which test should be done on diabetic persons once per year? A. Urine glucose B. Urine ketones C. Plasma fructosamines D. Estimated glomerular filtration rate

9. D While urinary glucose can identify persons who may have diabetes, it is not sensitive enough to manage glucose control on a daily basis, and has been replaced by whole-blood glucose monitoring or continuous glucose monitoring. While the urinary ketone test is a useful screening test for diabetic and other forms of ketosis, the plasma β hydroxybutyrate test should be used to identify and monitor ketosis in diabetic persons. Fructosamine is a useful adjunct to Hgb A1c to identify poor control of blood glucose in the past 2-4 weeks, but has not been recommended for routine use in all diabetic patients

What is the recommended cutoff for the early detection of chronic kidney disease in diabetics using the test for microalbuminuria? A. >30 mg/g creatinine B. >80 mg/g creatinine C. >200 mg/g creatinine D. >80 mg/L

A Microalbuminuria is the excretion of small quantities of albumin in the urine. In diabetics, excretion of albumin that is within allowable limits for healthy persons may signal the onset of chronic kidney disease. The term microalbuminuria is defined as albumin excretion ≥ 30 mg/g creatinine but ≤ 300 mg/g creatinine. The use of the albumin to creatinine ratio is preferred to measures of albumin excretory rate (μg/min) because the latter is subject to error associated with timed specimen collection. ADA recommends the test be done annually for all type 2 diabetics and type 1 diabetics who have had the disease for > 5 years.

Which statement regarding measurement of Hgb A1c is true? A. Levels do not need to be done fasting B. Both the labile and stable Hgb A1c fractions are measured C. Samples should be measured within 2 hours of collection D. The assay must be done by chromatography

A Since Hgb A1C represents the average blood glucose 2-3 months prior to blood collection, the dietary status of the patient on the day of the test has no effect upon the results. Refrigerated whole-blood samples are stable for up to 1 week. Hgb A1C is assayed by cation exchange high-performance liquid chromatography or immunoassay (immunoturbidimetric inhibition) because both methods are specific for stable Hgb A1C, and do not demonstrate errors caused by abnormal hemoglobins, temperature of reagents, or fractions other than A1c.

Select the coupling enzyme used in the hexokinase method for glucose. A. Glucose-6-phosphate dehydrogenase B. Peroxidase C. Glucose dehydrogenase D. Glucose-6-phosphatase

A The hexokinase reference method uses a protein-free filtrate prepared with barium hydroxide (BaOH) and zinc sulfate (ZnSO4). Hexokinase catalyzes the phosphorylation of glucose in the filtrate using ATP as the phosphate donor. Glucose-6-phosphate (glucose-6-PO4) is oxidized to 6-phosphogluconate and NAD+ is reduced to NADH using G-6-PD. The increase in absorbance at 340 nm is proportional to glucose concentration. Although hexokinase will phosphorylate some other hexoses including mannose, fructose, and glucosamine, the coupling reaction is entirely specific for glucose-6-PO4 eliminating interference from other sugars.

Fasting plasma glucose Done when, preparation value

After 8 hr fast 126 mg/dl on more than 2 occasions is indicative of diabetes.

7. According to American Diabetes Association criteria, which result is consistent with a diagnosis of impaired fasting glucose? A. 99 mg/dL B. 117 mg/dL C. 126 mg/dL D. 135 mg/dL

B Impaired fasting glucose is defined as a plasma glucose ≥100 but <126 mg/dL. A fasting glucose of 126 or higher on two consecutive occasions indicates diabetes. A fasting glucose of 99 mg/dL is considered normal.

2. Polarographic methods for glucose analysis are based upon which principle of measurement? A. Nonenzymatic oxidation of glucose B. The rate of O2 depletion C. Chemiluminescence caused by formation of adenosine triphosphate (ATP) D. The change in electrical potential as glucose is oxidized

B Polarographic glucose electrodes measure the consumption of O2 as glucose is oxidized. Glucose oxidase in the reagent catalyzes the oxidation of glucose by O2 under first-order conditions, forming hydrogen peroxide (H2O2). As the dissolved O2 decreases, less is reduced at the cathode, resulting in a decrease in current proportional to glucose concentration. It is important that the H2O2 not breakdown to re-form O2. This is prevented by adding molybdate and iodide that react with H2O2, forming iodine and water, and by adding catalase and ethanol that react with H2O2, forming acetaldehyde and water.

When preparing a patient for an oral glucose tolerance test (OGTT), which of the following conditions will lead to erroneous results? A. The patient remains ambulatory for 3 days prior to the test B. Carbohydrate intake is restricted to below 150 g/day for 3 days prior to test C. No food, coffee, tea, or smoking is allowed 8 hours before and during the test D. Administration of 75 g of glucose is given to an adult patient following a 10-12-hour fast

B Standardized OGTTs require that patients receive at least 150 grams of carbohydrate per day for 3 days prior to the test in order to stabilize the synthesis of inducible glycolytic enzymes. The 2-hour OGTT test is no longer recommended for screening and should be reserved for confirmation of diabetes in cases that are difficult to diagnose, such as persons who lack symptoms and signs of fasting hyperglycemia.

Which of the following is the reference method for measuring serum glucose? A. Somogyi-Nelson B. Hexokinase C. Glucose oxidase D. Glucose dehydrogenase

B The hexokinase method is considered more accurate than glucose oxidase methods because the coupling reaction using glucose-6-phosphate dehydrogenase (G-6-PD) is highly specific. The hexokinase method may be done on serum or plasma collected using heparin, EDTA, fluoride, oxalate, or citrate. The method can also be used for urine, cerebrospinal fluid, and serous fluids

170. At what level should a 52-year-old male diagnosed with type 2 diabetes mellitus maintain his hemoglobin A]c? A. <3% B. <7% C. <9% D. <11%

B. <7%...

162. Which of the following is not associated with hypoglycemia? A. Neuroglycopenia B. Symptoms occur with plasma glucose level of 60-70 mg/dL C. Decreased hepatic glucose production D. Diagnostic test is 72-hour fast

B. The diagnostic test for hypoglycemia is the 72-hour fast, which requires the analysis of glucose, insulin, C-peptide, and proinsulin at 6- hour intervals. The test should be concluded when plasma glucose levels drop to <45 mg/dL, when hypoglycemic symptoms appear, or after 72 hours have elapsed. In general, hypoglycemic symptoms occur when the plasma glucose level falls below 55 mg/dL. Such symptoms may include headache, confusion, blurred vision, dizziness, and seizures. The term "neuroglycopenia" has been applied to these central nervous system disorders. Although decreased hepatic glucose production and increased glucose utilization may cause hypoglycemia, there are over 100 causes of this disorder....

How is blood glucose level kept constant during a fast, both long term and short term?

By mobilizing the bodies' glycogen stores in the liver. Body's supply of glycogen is used up with 24-48 hrs so Gluconeogenesis occurs in longer fasts. Gluconeogenesis is formation of glucose from non protein sources such as fats and proteins. In a fasting situation, first glycogen stores are used, then proteins, then fats.

Which statement regarding glycated (glycosylated) Hgb (G-Hgb) is true? A. Has a sugar attached to the C-terminal end of the β chain B. Is a highly reversible aminoglycan C. Reflects the extent of glucose regulation in the 8- to 12-week interval prior to sampling D. Will be abnormal within 4 days following an episode of hyperglycemia

C G-Hgb results from the nonenzymatic attachment of a sugar such as glucose to the N-terminal valine of the β chain. The reaction is nonreversible and is related to the time-averaged blood glucose concentration over the life span of the RBCs. There are three G-Hgb fractions designated A1a, A1b, and Alc. Hemoglobin A1c makes up about 80% of glycated hemoglobin, and is used to determine the adequacy of insulin therapy. The time-averaged blood glucose is approximated by the formula (G-Hgb × 33.3) - 86 mg/dL, and insulin adjustments can be made to bring this level to within reference limits. Also, glycated protein assay (called fructosamine) provides similar data for the period between 2 and 4 weeks before sampling

Select the most appropriate adult reference range for fasting blood glucose. A. 40-105 mg/dL (2.22-5.82 mmol/L) B. 60-140 mg/dL (3.33-7.77 mmol/L) C. 65-99 mg/dL (3.61-5.50 mmol/L) D. 75-150 mg/dL (4.16-8.32 mmol/L)

C Reference ranges vary slightly depending upon method and specimen type. Enzymatic methods specific for glucose have an upper limit of normal no greater than 99 mg/dL. This is the cutoff value for impaired fasting plasma glucose (prediabetes) recommended by the American Diabetes Association. Although 65 mg/dL is considered the 2.5 percentile, a fasting level below 50 mg/dL is often seen without associated clinical hypoglycemia, and neonates have a lower limit of approximately 40 mg/dL owing to maternal insulin.

0. Which testing situation is appropriate for the use of point-of-care whole-blood glucose methods? A. Screening for type 2 diabetes mellitus B. Diagnosis of diabetes mellitus C. Monitoring of blood glucose control in type 1 and type 2 diabetics D. Monitoring diabetics for hyperglycemic episodes only

C The ADA does not recommend the use of whole-blood glucose monitors for establishing a diagnosis of diabetes or screening persons for diabetes. The analytical measurement range of these devices varies greatly, and whole blood glucose is approximately 10% lower than serum or plasma glucose. In addition, analytical variance is greater and accuracy less than for laboratory instruments. Whole blood glucose meters should be used by diabetics and caregivers to monitor glucose control and can detect both hyper- and hypoglycemic states that result from too little or too much insulin replacement. Therefore, postprandial monitoring with such a device is recommended for all persons who receive insulin therapy.

4. Which of the following is characteristic of type 2 diabetes mellitus? A. Insulin levels are consistently low B. Most cases require a 3-hour oral glucose tolerance test to diagnose C. Hyperglycemia is often controlled without insulin replacement D. The condition is associated with unexplained weight loss

C Type 2, or late-onset diabetes, is associated with a defect in the receptor site for insulin. Insulin levels may be low, normal, or high. Patients are usually obese and over 40 years of age, although the incidence is increasing in both children and young adults. The American Diabetes Association (ADA) recommends screening all adults for diabetes who are overweight and have one additional risk factor and all adults over age 45, and to retest them every 3 years, if negative. Patients do not require insulin to prevent ketosis and hyperglycemia can be controlled in most patients by diet and drugs that promote insulin release. Type 2 accounts for 80%-90% of all diabetes mellitus.

8. Which of the following 2-hour glucose challenge results would be classified as impaired glucose tolerance (IGT)? Two-hour serum glucose: A. 130 mg/dL B. 135 mg/dL C. 150 mg/dL D. 204 mg/dL

C With the exception of pregnant females, impaired glucose tolerance is defined by the ADA as a serum or plasma glucose at 2 hours following a 75-g oral glucose load of ≥140 mg/dL and < 200 mg/dL. Persons who have a fasting plasma glucose of ≥100 but < 126 mg/dL are classified as having impaired fasting glucose (IFG). Both IGT and IFG are risk factors for developing diabetes later in life. Such persons are classified as having prediabetes and should be tested annually.

156. Which of the following is not associated with insulin? A. Synthesized from proinsulin B. Synthesized by Beta-cells in the pancreas C. C-peptide is active form D. Two-chain polypeptide

C. The protein hormone insulin is synthesized in the pancreas by the Beta-cells of the islets of Langerhans. Insulin, a two-chain polypeptide, consists of 51 amino acids. A single-chain preproinsulin is cleaved to proinsulin, which is the immediate precursor of insulin. Proinsulin is hydrolyzed to form insulin, a two-chain polypeptide, and inactive C-peptide. Insulin promotes the entry of glucose into tissue cells. Preproinsulin forms proinsulin Pro insulin forms insulin (a two polypeptide molecule) and an inactive C peptide.

5. Which of the following results falls within the diagnostic criteria for diabetes mellitus? A. Fasting plasma glucose of 120 mg/dL B. Two-hour postprandial plasma glucose of 160 mg/dL C. Two-hour plasma glucose of 180 mg/dL following a 75 g oral glucose challenge D. Random plasma glucose of 250 mg/dL and presence of symptoms

D The American Diabetes Association recommends the following criteria for diagnosing diabetes mellitus: fasting glucose ≥ 126 mg/dL, casual (random) glucose ≥ 200 mg/dL in the presence of symptoms (polyuria, increased thirst, weight loss), glucose ≥ 200 mg/dL at 2 hours after an oral dose of 75 g of glucose, and hemoglobin A1c ≥ 6.5%. A diagnosis of diabetes mellitus is indicated if any one or combination of these four criteria is met on more than a single testing event. The fasting plasma glucose test requires at least 8 hours with no food or drink except water. The 2-hour postloading test should be conducted according to the oral glucose tolerance guidelines currently recommended by the World Health Organization

150. Of the following blood glucose levels, which would you expect to result in glucose in the urine? A. 60mg/dL B. 120mg/dL C. 150mg/dL D. 225mg/dL

D. Renal threshold is defined as the plasma level that must be exceeded in order for the substance to appear in the urine. The renal threshold for glucose is 180 mg/dL. This means that the blood glucose level must exceed 180 mg/dL in order for glucose to be excreted in the urine. ...

Type 2 diabetes mellitus Characteristics Age group

Defect in insulin secretion and cellular resistance to insulin not dependent on treatment with insulin. Individuals generally respond to dietary intervention and oral hypoglycemic agents, but some may require insulin therapy Non-ketosis prone: Without exogenous insulin or oral hypoglycemic medication, these individuals will have an elevated glucose but will not go into diabetic ketoacidosis. Over 40 but increasingly seen in children

Major biochemical pathways of carbohydrate metabolism

Embden-Meyerhoff pathway Hexose monophosphate shunt pathway (HMP shunt) Glycogenesis

Glycogen storage diseases are? Caused by? Most common types are?

Enzyme disorders which cause problems with glycogen storage Enzyme deficiencies affecting either glycogen synthesis, glycogen breakdown or glycolysis (glucose breakdown), Categorized by number and name. Type 1 is called Von Gierke disease and is most common. Deficiency of the enzyme glucose-6-phosphatase Type 2 is Pompe's disease, due to acid maltase deficiency

Von Gierke (Type I)

Glucose-6-phosphatase. Can't convert G6P into glucose during gluconeogenesis. Structurally normal glycogen accumulates in liver and kidney.

Epinephrine

Neurotransmitter secreted by the adrenal medulla in response to stress. Also known as adrenaline. raises glucose by stimulating glycogenolysis.

Glucose oxidase method

Oxidized chromogen is colored

Type 1 diabetes symptoms Characteristic feature

Polyuria, polydipsia weight loss Ketosis prone excess of ketones produced

Cortisol

Produced by adrenal cortex (zona fasciculata) Increases glucose levels Stimulates gluconeogenesis (glucose from non carbohydrate sources)

glucosuria.

glucose in urine

Diabetes melitus

group of diseases characterized by hyperglycemia due to defects in insulin production, insulin action, or both.

fructosamine test

measures average glucose levels over the past 3 weeks Ketoamine linkage forms between glucose and protein, mainly represented by albumin.

Gestational diabetes mellitus (GDM)

onset of diabetes mellitus during pregnancy. After childbirth, the individual generally returns to normal metabolism. However, there is an increased chance that type 2 diabetes mellitus may develop later in life Placental lactogen inhibits action of insulin.