Clinical Chemistry test 3

Which of the following methods of measuring enzyme activity utilizes an increase in absorbance at 340 nm as an indicator reaction?

"Forward" LD reaction

Insulin may be described by all of the following EXCEPT:

Active in its C-Peptide form

A reaction rate assay measures enzyme ____________________; an endpoint assay measures enzyme ______________________.

Activity; activity

Type 1 diabetes mellitus may be described by all of the following EXCEPT:

Adult-onset type

Of the following, the only clinically analyzed enzyme in the urine is:

Amylase

One extracellular enzyme whose serum activity is measured clinically is:

Amylase

Which of the following enzymes requires chloride (Cl-) as an activator?

Amylase

Azotemia refers to:

An increase in urea in blood

The glucose value of a NORMAL 2-hour post-prandial serum specimen, as compared to the reference range for a fasting serum glucose, should be:

Approximately the same as the normal fasting glucose level

The major non-glucose-reducing substance present in serum is:

Ascorbic acid

The ____________ form of glucose is responsible for its reducing properties.

Enol

Which of the following enzymes detects very early changes in liver cell damage?

GGT

The formation of glucose from compounds like fatty acids, glycerol, and amino acids is called:

Gluconeogenesis

Which of the following enzyme tests is most affected by "hemolysis?

Lactate dehydrogenase

True or false? Indirect urea methods begin with the hydrolysis of urea to ammonia.

True

True or false? Serum uric acid levels may be elevated in patients undergoing cancer chemotherapy.

True

The abbreviated Modification of Diet in Renal Disease (MDRD) equation considers all of the following variables EXCEPT:

Urine creatinine concentration

When myocardial infarction occurs, the first enzyme to reach peak elevation is:

CK

During 3 glucose tests an hour apart on a patient, capillary blood is substituted for venous blood for one of the timed samples. What results would you expect for the sample, as compared to results expected for venous blood drawn at the same time?

Capillary blood will yield higher results than venous blood

In the Beckman Analyzer for glucose, H2O2 is consumed in side reactions by:

Catalase and ethyl alcohol

Of the following drug therapies, which is MOST likely to interfere with the Jaffe chemistry for measuring creatinine?

Cephalosporin

The following glucose tolerance test results are indicative of what state? Glucose values as assayed by glucose oxidase method are fasting, 130 mg/dL; 60 minutes, 225 mg/dL; and 120 minutes, 205 mg/dL.

Diabetes

Glycation of glomerular basement membranes and capillaries is the main nephropathic effect from:

Diabetes mellitus

Which of the following best describes the correct collection and handling conditions for a blood ammonia measurement?

Draw sodium heparin tube, place in ice bath immediately, separate cells and plasma in refrigerated centrifuge, immediately remove plasma and freeze if analytical testing is delayed

When a purified enzyme is used as a reagent, such as urease in the measurement of urea, the enzyme must be ________________ concentration so that the reaction follows _________________ kinetics.

Excess; first

True or false? In a "kinetic" or "rate" reaction, one spectrophotometric measurement is taken at the end of an incubation period.

False

True or false? Serum urea levels are less affected by diet and metabolism than are serum creatinine levels.

False

The most sensitive enzymatic indicator for liver damage from ethanol intake is:

Gamma-glutamyl transferase (GGT)

β-glucose + O2 ----?-----> D-glucono-δ-lactone + H2O2

Glucose oxidase

A diabetic patient is prescribed a daily regimen of insulin. Which of the following laboratory procedures would be of most value in determining the degree of glucose control over a 2-month period?

Glycated hemoglobin

In the Szasz method for gamma glutamyl transferase (GGT), the typical receptor molecule is:

Glycyl glycine

Which of the following inhibits glycolysis and glucose uptake by muscle cells and causes a rise in blood glucose concentration?

Growth hormone

The reference method for glucose determination is:

Hexokinase

Which of the following methods for glucose results in the formation of NADPH for measurement?

Hexokinase

Urea:

Is synthesized from CO2 and ammonia

Which of the following enzymes has multiple molecular forms (isoenzymes) whose clinical significance is used in diagnosis?

Lactate dehydrogenase, creatine kinase, and alkaline phosphatase

The enzyme that is inhibited by hemoglobin is:

Lipase

The major causes of decreased plasma urea concentration include:

Low protein intake and sever liver disease

Which of the following is NOT considered a coenzyme?

Magnesium

One International Unit is defined as one __________ of substrate converted to product per ___________.

Micromole; minute

Laboratory tests are performed on a post-menopausal, 57-year-old woman as part of an annual physical examination. The patient's 2-hour post-prandial glucose is 220 mg/dL and serum insulin is 15 μU/ml (normal = 6-26). Based on this information, the patient would be classified as:

Non-insulin-dependent diabetes mellitus (NIDDM)

In the spectrophotometric determination of AST, malic dehydrogenase catalyzes the conversion of:

Oxalacetate to malate

A reaction in which NAD+ or NADP+ is formed from reagent NADH or NADPH is ________ and may be measured by a(an) ________ in absorbance at 340 nm.

Oxidation; decrease

Prostatic acid phosphatase measurement has been replaced by:

PSA

An elevated aldolase level and normal myoglobin is most indicative of:

Progressive muscular dystrophy

The major cellular origin of acid phosphatase activity in serum is:

Prostate

Monitoring of _______ in patients on chemotherapy due to leukemia, lymphoma or multiple myeloma is necessary to avoid nephrotoxicity.

Serum uric acid

The greatest tissue source of CK is:

Skeletal muscle

In the commonly used ("Caraway") colorimetric method for uric acid in serum, interference from other reducing substances such as ascorbic acid is minimized by the addition of:

Sodium Carbonate

The preferred collection tube for preservation of glucose is:

Sodium fluoride

Which of the following statements may be associated with the activity of insulin?

Stimulates glycogenesis in the liver

Urea can be measured in all of the following ways EXCEPT:

The Caraway method

True or false? An enzymatic method for creatinine on the Vitros (Kodak Ektachem) analyzer uses the reagent enzyme creatinine amidohydrolase.

True

A toxic condition involving a very high serum level of urea and creatinine accompanied by failure of the three main functions of the renal system is referred to as:

Uremia

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are both elevated in which of the following diseases?

Viral hepatitis

A serum specimen for glucose measurement was allowed to stand unseparated on the clot for 6 hours at room temperature before testing. If the original glucose concentration was 200 mg/dL, what approximate results would be expected after 3 hours?

160 mg/dL