ASCP MLT Chemistry

Which element in proteins differentiates substance from carbohydrates and lipids?

nitrogen

What proteins is soluble in water?

albumin

How are amino acids joined together to form a chain like structure?

peptide bonding

Proteins may become denatured when subjected to?

mechanical agitation, heat, chemical treatments

What does denaturation of proteins refer to?

alteration in tertiary structure

Which aminoacidopathy is NOT caused by an enzyme deficiency?

cystinuria

How many immunoglobulin classes are currently recognized?

five

which reagent is employed in the serum protein determination?

biuret

What should hemolyzed serum not be used for total protein analysis?

hemoglobin is absorbed at the same wavelength as protein in the reagent

What is NOT true of the biuret reaction?

is relatively free from interference by lipids and hemoglobin

Why is bromcresol purple the preferred indicator for albumin dye binding techniques?

there is less interference from pigment (s)

What is the most anodic protein on electrophoresis at pH 8.6?

albumin

A serum protein electrophoretic pattern displaying a beta gamma bridge or broad gamma is seen in which disease state?

acute inflammation

If an electrophoretic pattern shows 30% albumin, 4%-10% alpha-globulin, 4-10% beta-globulin, and 45% gamma-globulin, then what condition may exist in the patient?

monoclonal gammopathy

Glycoproteins and mucoproteins are usually bound to which substance?

carbohydrates

Name some glycoproteins?

ceruloplasmin, follicle-stimulating hormone, cryoglobulin

What applies to cryoglobulins?

they are temperature-sensitive proteins

What is true of albumen?

it is produced in the liver and it is water soluble

Decreased alpha-fetoprotein values are associated with what condition?

Down Syndrome

What protein transports iron?

transferrin

In acute renal failure, what non protein nitrogen rises the fastest?

blood urea nitrogen

By the urease method, urea is enzymatically converted to which end product?

ammonia

Why can untreated urine be used for the determination of urea by the diacetyl monoxime method?

The method is not measureing ammonia

An elevated creatinine value is most likely to be accompanied by what values?

elevated blood urea nitrogen, 10X creatinine value

What is the classical method for creatinine reaction?

Jaffe

The measurement of creatinine is based on the formation of a yellow-red color and which reagent?

titan yellow

The creatinine clearance test is based on what assumption?

Creatinine passes into the ultrafiltrate

What is the most common clearance test used to measure the glomerular filtration rate?

creatinine

Creatinine clearance formula

UV/P

or UV/P (1.73/correction factor)

1440 mls/min

A creatinine clearance test is performed. The 24-hour urine volume is 770 mL; serum creatinine is 2.0 mg/dL and urine creatinine is 240 mg/dL. What is the clearance, assuming average body surface area?

64 mL/minute

What disease state is associated with an elevation of serum uric acid?

gout

Which reagent is employed in the alkaline oxidation of uric acid?

phosphotungistic acid

What does the uricase method for uric acid depend on?

ultraviolet absorption at 290 nm before/after treatment with uricase

Which analytes is used as a prognostic indicator for liver failure?

ammonia

Which disaccharide is composed of two glucose molecules?

maltose

What term is used to describe the process of glycogen degradation?

glycogenolysis

What is the renal threshold for glucose?

140-160 mg/dL

Which hormone is produced by the beta cells of the islets of Langerhans?

insulin

What hormones is considered a glucocorticoid?

cortisol

A 40-year-old male has a random glucose of 470 mg/dL. This lab finding is consistent with what clinical conditions?

DIABETES MELLITUS

What disease is associated with hypoglycemia?

von Gierke's disease

What is the specimen of choice for glucose determinations?

fluorinated plasma

What is the most frequently employed automated method for glucose?

coupled enzyme system consisting of glucose oxidse and peroxidase

Contamination of the glucose reagent with catalase is a problem with what glucose method?

glucose oxidase

What is the hexokinase methodology for glucose determination based on?

coupled enzymatic reaction consisting of oxidase and peroxidase

What is the normal fasting blood glucose reference range for adults?

70-110 mg/dL

Prenatal patients with borderline blood glucose levels are further evaluated by what test?

3-hour glucose tolerance test

Which test gives a 2- to 3-month picture of a diabetic's glucose levels?

hemoglobin A1C

What does the presence of urinary ketones MOST likely indicate?

Storage lipids are being used as the primary energy source

Which test is used to differentiate between inappropriate exogenous insulin administration and endogenous insulin production?

Beta-microglobulin

The "port-wine" color some urines can be attributed to what?

porphyrins

p-dimethylaminobenzaldehyde is a constituent of what reagent?

Ehrlich

Both porphobilinogen and urobilinogen form a red-colored compound with Ehrlich's regent. How can they be differentiated?

Porphobilinogen is soluble in chloroform

Prehepatic bilirubin has which protein carrier?

albumin

Direct-reacting bilirubin is also known as what substance?

unconjugated bilirubin

An increase in indirect-reacting bilirubin is suggestive of what condition?

bile acid reflux

Bilirubin is converted in the intestine to what substance?

urobilin

What will interfere with the Evelyn Malloy method for bilirubin?

hemolysis

Which precaution should be followed in regard to specimen handling instructions for bilirubin determinations?

protect from light

Which definition best describes an enzyme?

inorganic catalyst

What is true of an isoenzyme?

The rate of reaction is the same for each enzyme with its own substrate

Why is a metal ion sometimes necessary in an enzymatic reaction?

regulates pH

The Michaelis-Menten constant in the rate of conversion of substrate to product is determined by what factor?

temperature, pH, and substrate concentration

In a zero-order reaction, there will be no further increase in velocity due to what?

all enzyme is bound to substrate

what is the reporting unit of measure for enzymes?

IU/L

What enzyme catalyzes this reaction? lactate + NAD pyruvate + NADH?

aldolase

What is true of the isoenzyme LD1?

It is present in the highest concentration in heart tissue

An LD isoenzyme electrophoretic pattern that shows an increase in LD1, LD2, LD3 is seen in what disease state?

renal disease

Creatine kinase is clinically significant in diseases of what organ?

brain

Creatine kinase is frequently elevated in acute myocardial infarction and which other disorder?

acute viral hepatitis

Which serum enzyme begins to rise 2 to 4 hours, has peak activity occurring 12 to 36 hours, and returns to normal 2 to 4 days after an acute myocardial infarction?

aspartate transaminase

Aspartate transaminase is elevated in what condition EXCEPT?

acute pancreatitis

What enzyme is liver specific?

alanine transaminase

What enzyme is the most sensitive indicator of obstructive jaundice?

alkaline phosphatase

A high alkaline phosphatase level in the presence of other negative liver function tests is indicative of which disorder?

ectopic pregnancy

What is the optimum pH for acid phosphatase?

3.0

What is the clinical significance of an elevated acid phosphatase?

prostatic disease

Which enzyme may be monitored in recovering alcoholics?

gamma-glutamyl transferase

Which enzyme is characteristically elevated in mumps?

amylase

Lipase catalyzes the hydrolysis of what substrate?

triglycerides

What is the substrate for the Cherry-Crandall lipase method?

glycerol

In what disease state are the highest levels of aldolase seen?

muscular dystrophy

Because ionized calcium can be changed without affecting the total calcium level, what other parameter (s) must be known to properly evaluate calcium?

pH and protein

What doesn't regulate calcium levels?

aldosterone

What regulates calcium levels?

Vitamin D, calcitonin, parathyroid hormone

What specimen is acceptable for the determination of total calcium?

oxalated plasma

In the complexometric titration (EDTA) method for calcium, the pH must be adjusted to prevent what occurrence?

co-binding of phosphorus

the classic Clark-Collip method for calcium is based on which assumption?

Calcium will be chelated with EDTA

What is the purpose of lanthanum in the atomic absorption determination of calcium?

it will bind calcium

At a pH of 7.4, most of the phosphorus in the body is in what form?

DNA/RNA

Inorganic phosphate can be determined from a colorimetric method involving what reagent?

alkaline picrate

A labor and delivery patient with preeclampsia is being treated for premature contractions. What is the most likely laboratory finding?

hypermagnesemia

The colorimetric method for magnesium employs what reagent?

titan yellow

What is the most abundant iron-containing compound in the body?

ferritin

Why should serum iron be drawn at the same time on consecutive days?

to avoid the effect of medication

Which protein transports the majority of copper in the bloodstream?

ceruloplasmin

Increased serum copper is seen in what disease?

Menkes syndrome

What analyte is an early indicator of tissue hypoxia?

lactic acid

What is the major extracellular cation?

chloride

What hormone acts on the distant convoluted tubule to increase sodium reabsorption?

aldosterone