Biochemistry EOR
Which of the following is the most likely interpretation of an increase of LD isoenzyme 5 only? A. myocardial infarction B. megaloblastic anemia C. acute pancreatitis D. viral hepatitis
D. viral hepatitis 5 = Viral hep
How are ALP isoenzymes used to determine bone or liver specificity?
isolate bone-specific or liver-specific ALP by heating an aliquot of the serum sample at 56°C for 10 minutes. An untreated aliquot of the sample along with the heated one are assayed for ALP activity. Heat Stable: Placenta > Liver/Intestine > Bone : Heat Labile
Which of the following would be considered a normal cerebrospinal fluid glucose level if the serum glucose is 70 mg/dL? About 100 mg/dL About 45 mg/dL About 60 mg/dL About 70 mg/dL
About 45 mg/dL (2/3 serum)
Purines
Adenine and Guanine Break down into uric acid
What are the negative acute phase reactants?
Albumin Transferrin Transthyretin
Which of the following enzymes is associated with conditions affecting skeletal muscles? Aldolase Alkaline phosphatase (ALP) Gamma-glutamyl transferase 5'-nucleotidase
Aldolase
What are the positive acute phase reactants?
Alpha-1-antitrypsin Alpha-1- acid glycoprotein Ceruloplasmin C3, C4 C-reactive protein Fibrinogen Haproglobin Serum amyloid
Acute phase reactants can be found in what fraction in a SPE? Albumin Alpha-1 Alpha-2 Beta Gamma
Alpha-2
What are the water soluble vitamins?
B & C vitamins: 1 Thiamin B1 2 Riboflavin B2 3 Niacin B3 6 Pyridoxine 12 Cobalamin Folate Folic Acid Biotin Pantothenic Acid Vitamin C
Which of the following is the most likely interpretation of an increase of LD isoenzymes 1 & 2? A. nephrotic syndrome B. hemolytic anemia C. pancreatitis D. hepatic damage
B. hemolytic anemia also pernicious anemia
The major action of angiotensin II is: A. increased pituitary secretion of vasopressin B. increased vasoconstriction C. increased parathormone secretion by the parathyroid D. decreased adrenal secretion of aldosterone
B. increased vasoconstriction --> Increase Blood Pressure Secondary is to increase Adrenal Cortex secretion of Aldosterone --> Retain H2O + Na in Kidney --> Increase blood volume
Alkaline phosphatase (ALP)
most useful clinical attribute is its sensitivity in distinguishing hepatobiliary disease associates with biliary tree obstruction. It is also used to detect bone disease associated with elevated osteoblastic activity.
Fehling's test
screen for reducing sugars (oxidizes sugars) Aldehyde can reduce Cu2+ to Cu+
A patient with glomerulonephritis is most likely to present with the following serum results: A. creatinine decreased B. calcium increased C. phosphorous decreased D. BUN increased
D. BUN increased
On electrophoresis at acid pH (6.2), which of the following is the slowest migrating hemoglobin? A. Hgb A B. Hgb S C. Hgb C D. Hgb F
D. Hgb F Cathode - < F A S C < + Anode Move towards Cathode
Pellagra is associated with deficiency of which of the following vitamins? A. A B. B1 C. thiamine D. niacin
D. niacin Pelicans ... niac Vitamin B3 The 3 "D's" clinical presentation: -Diarrhea -Dementia -Dermatitis
Which porphyria has a defect in the ferrochetalase enzyme within the RBC, causing redness, edema and burning when exposed to light? Erythropoietic protoporphyria Congenital erythropoietic porphyria X-linked protoporphyria Variegate porphyria
Erythropoietic protoporphyria
In hemoglobin synthesis, which enzyme is responsible for adding iron in the last step? ALA Synthase Ferrochelatase PBG Synthase Protoporphyrinogen oxidase
Ferrochelatase
Which type of kinetic reactions are reactions in which the enzyme is in excess and the substrate concentration is the limiting factor? Zero order First order Second order Third order
First order
Benedict's / Copper Reduction test
a simple screening test using a biochemical reaction to detect the presence of reducing sugars, not just glucose. Positive requires a confirmatory test
Beer's Law
explains the relationship between absorbance, at a given wavelength and concentration, A = εbc Direct relationship
5'-nucleotidase (5NT) detects
hepatobiliary disease with high specificity
What may cause solvent displacing effect resulting in decreased electrolyte values?
high concentrations of lipid and protein in the sample
ferritin
iron storage protein
TSH is produced by the: A. hypothalamus B. pituitary gland C. adrenal cortex D. thyroid
B. pituitary gland
Which of the following substances is the biologically active precursor of a fat soluble vitamin? A. biotin B. retinol C. folic acid D. ascorbic acid
B. retinol is the precursor to Vitamin A
The recommended initial thyroid function test for either a healthy, asymptomatic patient or a patient with symptoms which may be related to a thyroid disorder is: A. free thyroxine (free T4) B. thyroid-stimulating hormone (TSH) C. total thyroxine (T4) D. triiodothyronine (T3)
B. thyroid-stimulating hormone (TSH)
One international unit (IU) of enzyme activity is the amount of enzyme that will, under specified reaction conditions of substrate concentration, pH and temperature, cause utilization of substrate at the rate of: A. 1 mol/min B. 1 mmol/min C. 1 µmol/min D. 1 nmol/min
C. 1 µmol/min
On electrophoresis at alkaline pH (8.4), which of the following is the slowest migrating hemoglobin? A. Hgb A B. Hgb S C. Hgb C D. Hgb F
C. Hgb C Cathode - < CSF A < + Anode Move towards Cathode
In the immunoinhibition phase of the CKMB procedure: A. M subunit is inactivated B. B subunit is inactivated C. MB is inactivated D. BB is inactivated
A. M subunit is inactivated
Given: ALP: Slight increased AST: Marked increased ALT: Marked increase GGT: Slight increase What is the most likely disorder? A. acute hepatitis B. chronic hepatitis C. obstructive jaundice D. liver hemangioma
A. acute hepatitis
In the Jendrassik-Grof method for the determination of serum bilirubin concentration, quantitation is obtained by measuring the green color of: A. azobilirubin B. bilirubin glucuronide C. urobilin D. urobilinogen
A. azobilirubin caffeine plus diazotized sulfanilic acid and the serum produces azobilirubin blue-green azobilirubin is measured
What stains are commonly used to stain protein bands after electrophoresis.
Bromophenol blue, amido black 10B, Ponceau S, and lissamine green
The most common cause of rapid nonlinearity following the timed lag phase in an enzyme kinetic assay is resolved by: A. addition of more coenzyme such as NADH to the reaction following the timed lag phase. B. preventing extraneous protein from binding to the E-S complex by making a protein free filtrate. C. decreasing the sample volume to dilute the enzyme so that substrate remains in excess during the reaction. D. eliminating metallic ions that may be making structural changes and inhibition to the enzyme active site.
C. decreasing the sample volume to dilute the enzyme so that substrate remains in excess during the reaction.
Which of the following is the most likely interpretation of an increase of LD isoenzymes 3? A. nephrotic syndrome B. hemolytic anemia C. pancreatitis D. hepatic damage
C. pancreatitis
A patient with myeloproliferative disorder has the following values: Hgb: 13 g/dL HCT: 38% WBC 30 x 10^3/uL PLT: 1000 x 10^3/uL Serum Na+: 140 mEq/L Serum K+: 7 mEq/L The serum K+ should be confirmed by: A. repeat testing of the original serum B. testing freshly drawn serum C. testing heparinized plasma D. atomic absorption spectrometry
C. testing heparinized plasma Because platelets release potassium, they can contribute to the concentration in the serum to be tested Potassium is greater in serum than in plasma due to release of K+ from platelets during clotting; remove clotting time
A blood creatinine value of 5.0 mg/dL (442.0 µmol/L) is most likely to be found with which of the following blood values? A. osmolality: 292 mOsm/kg B. uric acid: 8 mg/dL (475.8 µmol/L) C. urea nitrogen: 80 mg/dL (28.56 mmol/L) D. ammonia: 80 µg/dL (44 µmol/L)
C. urea nitrogen: 80 mg/dL (28.56 mmol/L)
Arterial blood gas (ABG) specimens not maintained in ice water nor analyzed immediately experience: cellular glycolysis which causes increase in carbon dioxide, decrease in oxygen and lowers pH.
Cellular glycolysis Increase in CO2 Decreased pH Decrease in O2
Acetest
Confirmatory test for ketones
Which one of the following cardiac biomarkers could detect a recent reinfarction? Troponin I (TnI) Troponin T (TnT) Lactate dehydrogenase (LD) Creatine kinase MB (CK-MB)
Creatine kinase MB (CK-MB)
Pyrimidines
Cytosine, Thymine & Uracil
A patient's blood was drawn at 8 am for a serum iron determination. The result was 85 µg/dL (15.2 µmol/L). A repeat specimen was drawn at 8 pm; the serum was stored at 4°C and run the next morning. The result was 40 µg/dL (7.2 µmol/L). These results are most likely due to: A. iron deficiency anemia B. improper storage of the specimen C. possible liver damage D. the time of day the second specimen was drawn
D. the time of day the second specimen was drawn Morning is the best time to conduct this test because that's when your iron levels are highest.
thyroxine is produced in the: A. hypothalamus B. pituitary gland C. adrenal cortex D. thyroid
D. thyroid
What are the expected results of the laboratory markers in iron deficiency anemia? Decreased serum iron, increased transferrin, decreased ferritin, decreased percent saturation, and increased total iron binding capacity. Decreased serum iron, decreased transferrin, decreased ferritin, variable percent saturation, and decreased total iron binding capacity. Decreased serum iron, decreased transferrin, increased ferritin, decreased percent saturation, and decreased total iron binding capacity. Decreased serum iron, normal or decreased transferrin, normal or increased ferritin, decreased percent saturation, and normal or decreased total iron binding capacity.
Decreased serum iron Decreased ferritin Decreased % saturation Increased transferrin Increased total iron binding capacity Increased erythrocyte protoporphyrin (eg Zinc PP)
An electrophoretic separation of lactate dehydrogenase isoenzyme that demonstrates elevation in LD-1 greater than LD-2 could be indicative of: A normal LD isoenzyme pattern Hemolysis Pancreatitis Hepatic injury
Hemolysis LD-1 and LD-2 are both increased during myocardial infarction (also pernicious anemia) since they are both present in heart muscle. In normal conditions, LD-2 is present in higher concentrations than LD-1. The reverse is true in myocardial infarction and during states of hemolysis. This term is referred to as the LD flip. Pancreatitis does cause increased levels of LD, but the LD-3 type is the most affected in this condition. Hepatic injury also increases levels of LD, but the LD-4 type is the most affected in this condition.
A 56-year old female was taken to the emergency room in a coma by her employer's nurse. She had lost 35 pounds in 3 months; she was always thirsty; drinking a lot of water and running to the bathroom. The following are her laboratory results: Results: (indicates reference range) pH: 7.11 (7.35-7.45) pCO2: 21 mm Hg (35-45 mm Hg) Glucose: 950 mg/dL (60-110 mg/dL) Serum osmolality: 365 mOsm/Kg (275-295 mOsm/Kg) Urine ketone: strongly positive (negative) Urine glucose: strongly positive (negative) What is the MOST likely cause of this patient's symptoms? Gestational diabetes Diabetes insipidus Insulin dependent diabetes mellitus Type II diabetes mellitus
Insulin dependent diabetes mellitus aka Type I
Methotrexate is a highly toxic medication that blocks DNA synthesis in all cells. What medication needs to be administered after methotrexate to prevent cytotoxic effects in normal cells of the body? Theophylline Leucovorin Digoxin Vancomycin
Leucovorin
hepatic iron index
Liver iron divided by patient age, greater than 2 is diagnostic.
serum iron
Measure of iron in blood (this iron WILL be bound to transferrin)
Sulfosalicylic acid test
Results: Precipitate starts to form at 40 to 60 C which dissolves at 100 C and reappears on cooling back to 40 to 60 C
What test can be used as a confirmatory test for proteinuria? Acetest Benedict's test Fehling's test Sulfosalicylic acid test
Sulfosalicylic acid test
Which of the following immunosuppressive drugs below has been associated with thrombus formation in patients with toxic levels? Tacrolimus Cyclosporine Sirolimus Mycophenolic acid
Tacrolimus
Benedict's test
Test for reducing sugars
L/S ratio
The amount of Lecithin and sphingomyelin found in the amniotic fluid > 2:1 = Mature lungs
What is a typical finding for determining the endpoint for the initial or iron-depletion phase of treatment for hereditary hemochromatosis (HH)? Please select the single best answer The serum ferritin decreases to between 20 and 50 ng/mL The hepatic iron index returns to normal The transferrin saturation drops below 20% The serum iron falls to below 35 µg/dL.
The serum ferritin decreases to between 20 and 50 ng/mL Ferritin levels will decrease rapidly as storage iron is depleted. Serum ferritin is an inexpensive, non-invasive laboratory test. The hepatic iron index is a calculation of the iron concentration in the liver and a sensitive indicator for determining the degree of excess iron deposition in the liver. However, this is an invasive and costly procedure which requires a liver biopsy. Transferrin saturation and serum iron will eventually decrease after iron stores have been depleted, however, they will not be the first indicators of successful treatment of HH.
Which of the following lipid results would be expected to be FALSELY elevated on a serum specimen from a non-fasting patient? Cholesterol Triglyceride HDL LDL (not calculated)
Triglyceride
Congenital erythropoietic porphyria there is a defect with: Ferrochetalase enzyme in the RBC Uroporphyrinogen III Synthase ALA Synthase
Uroporphyrinogen III Synthase
Coomassie Blue
Used in Total Protein Concentration binds with the protein which causes a shift in the absorbance maximum of the dye from 465 nm to 595 nm. The resulting increase in absorbance at 595 nm is used to determine the total protein concentration of the specimen.
What are the fat soluble vitamins?
Vitamins A, D, E, K
Hemoglobin S can be separated from hemoglobin D by which of the following methods? A. citrate agar gel electrophoresis at pH 5.9 B. thin-layer chromatography C. alkali denaturation D. agarose gel electrophoresis at pH 8.4
A. citrate agar gel electrophoresis at pH 5.9 HgbD migrates with S in alkaline electrophoresis but migrates with A in citrate acid electrophoresis. Alkaline denaturation is used in detecting and differentiating HgbF from other forms.
An infant with diarrhea is being evaluated for a carbohydrate intolerance. His stool yields a positive copper reduction test and a pH of 5.0. It should be concluded that: A. further tests are indicated B. results are inconsistent—repeat both tests C. the diarrhea is not due to carbohydrate intolerance D. the tests provided no useful information
A. further tests are indicated
TRH is produced in the: A. hypothalamus B. pituitary gland C. adrenal cortex D. thyroid
A. hypothalamus
The pituitary gland produces the hormones:
ACTH LH & FSH TSH PRL GH MSH (Melanocyte-stimulating hormone)
The posterior pituitary gland releases:
ADH Oxytocin
A physician requested that electrolytes on a multiple myeloma patient specimen be run by direct ISE and not indirect ISE because: A. excess protein binds Na in indirect ISE B. Na is falsely increased by indirect ISE C. Na is falsely decreased by indirect ISE D. excess protein reacts with diluent in indirect ISE
C. Na is falsely decreased by indirect ISE Pseudohyponatremia: A normal, 7% solids sample that an indirect ISE measurement would give you a value of 135 mmol/L; if the solids are 20%, that sample will give you a value of 116 mmol/L. This is called pseudohyponatremia. The sodium is not really low; it's perfectly normal. The instrument is giving you a falsely low value.
Which of the following diseases results from a familial absence of high density lipoprotein? A. Krabbe disease B. Gaucher disease C. Tangier disease D. Tay-Sachs disease
C. Tangier disease defect in the catabolism of Apo A-I, an essential apoprotein for HDL more common causes of hypoalphalipoproteinemia include LCAT deficiency and mutations of the APOA1 gene.
Which of the following serum protein fractions is most likely to be elevated in patients with nephrotic syndrome? A. alpha-1 globulin B. albumin C. alpha-2 globulin and beta globulin D. beta globulin and gamma globulin
C. alpha-2 globulin and beta globulin
Turbidity in serum suggests elevation of: A. cholesterol B. total protein C. chylomicrons D. albumin
C. chylomicrons
transferrin
iron transport protein The most widely used test for screening for HH is the transferrin saturation due to its sensitivity and specificity for iron overload. A transferrin saturation result of >45% is diagnostic for HH.
Which of the following methods is susceptible to the solvent displacing effect that results in falsely decreased electrolyte values? A. indirect ion-selective electrodes B. direct ion-selective electrodes C. alkaline electrophoretic separation of ions D. fluorescence
A. indirect ion-selective electrodes This effect is caused by the solvent displacing effect of high concentrations of lipid and protein in the sample resulting in falsely decreased values.
What disorder is characterized by highly elevated AST but near normal alkaline phosphatase when accompanied by: increased serum bilirubin increased conjugated/direct serum bilirubin increased urine urobilinogen positive urine bilirubin decreased fecal urobilinogen? A. unconjugated hyperbilirubinemia, probably due to hemolysis B. unconjugated hyperbilirubinemia, probably due to toxic liver damage C. conjugated hyperbilirubinemia, probably due to hepatocellular disease D. conjugated hyperbilirubinemia, probably due to hepatocellular obstruction
C. conjugated/direct hyperbilirubinemia, probably due to hepatocellular disease
In using ion-exchange chromatographic methods, falsely increased levels of HgbA1c might be demonstrated in the presence of: A. iron deficiency anemia B. pernicious anemia C. thalassemias D. HgbS
D. Hgb S Also with: Very high triglycerides (over 1,750), Bilirubin >20 mg/dL Uremia/Renal Failure Splenectomy (Hgb S - autosplenectomy) Anemias associated with decreased red cell turnover Chronic Drugs/Alcohol
The most consistent analytical error involved in the routine determination of HDL-cholesterol is caused by: A. incomplete precipitation of LDL-cholesterol B. coprecipitation of HDL- and LDL-cholesterol C. inaccurate protein estimation of HDL-cholesterol D. a small concentration of apoB-containing lipoproteins after precipitation
D. a small concentration of apoB-containing lipoproteins after precipitation
Malic dehydrogenase is added to the aspartate aminotransaminase (AST) reaction to catalyze the conversion of: A. alpha-ketoglutarate to aspartate B. alpha-ketoglutarate to malate C. aspartate to oxalacetate D. oxalacetate to malate
D. oxalacetate to malate
A blood gas sample was sent to the lab on ice, and a bubble was present in the syringe. The blood had been exposed to room air for at least 30 minutes. The following change in blood gases will occur: A. CO2 content increased/pCO2 decreased B. CO2 content and pO2 increased/pH increased C. CO2 content and pCO2 decreased/pH decreased D. pO2 increased/HCO3 decreased
D. pO2 increased/HCO3 decreased
An arterial blood specimen submitted for blood gas analysis was obtained at 8:30 am in a plastic syringe, but was not received in the laboratory until 11 am. The technologist should: A. perform the test immediately upon receipt B. perform the test only if the specimen was submitted in ice water C. request a venous blood specimen D. request a new arterial specimen be obtained
D. request a new arterial specimen be obtained They are only stable for 30 minutes (plastic) 60 minutes (glass)
What vitamin assays need to be protected from light?
Vitamin A: Retinol Vitamin B6: Pyridoxine
