Clinical Chem Exam 3

What interferes with the measurement of lactate dehydrogenase?

Hemolyzed specimens

Which of the following findings is consistent with a diagnosis of metabolic alkalosis? Low pCO2, increased HCO3 High pCO2, increased HCO3 High pCO2, decreased HCO3 Low pCO2, decreased HCO3

High pCO2, increased HCO3 *Increase in bicarb w/ CO2 compensation

Condition which may yield the following enzyme results? CK 185 (40-160 U/L) AST 105 (5-35 U/L)

Muscle crush injury *Muscle injury elevates both creatine kinase & Aspartate transaminase

An elevated Creatine Kinase and normal myoglobin is indicative of which of the following conditions?

Muscular dystrophy *CK elevation occurs due to muscle degradation

high serum osmolality indicates

dehydration diabetes mellitus/insipidus hypernatremia ingestion of alcohols

Syndrome of inappropriate ADH (SIADH)

excessive secretion of ADH (little urine output)

A BMP (Basic Metabolic Panel) usually consists of which group of tests?

glucose, BUN, creatinine, chloride, CO2, calcium, K, sodium *BMP= GBCCCCKS

A CMP (Comprehensive Metabolic Panel) usually consists of which group of tests?

glucose, BUN, creatinine, chloride, CO2, calcium, K, sodium, albumin, ALT, ASP, ALP, total protein, total bilirubin *Think CMP same as BMP plus the others CMP= GBCCCCKS + AAAAPB

metabolic alkalosis

high pH, high HCO3 *ME= metabolic equal

Respiratory alkalosis

high pH, low CO2 *ROME: Respiratory Opposite

Patients who develop severe sepsis commonly have ______________ plasma lactate level.

increased

Respiratory Acidosis is associated with

increased pCO2 *Lungs can't remove CO2: decreased pH w/ high CO2 ROME: Respiratory Opposite

Hypoxia

lack of oxygen

Metabolic acidosis is characterized by

low pH *Metabolic Equal

metabolic acidosis

low pH, low HCO3 ROME: Metabolic equal

excessive vomiting can lead to

metabolic alkalosis *Loss of H through vomiting causes high levels of pH. ROME: Metabolic

How are arterial blood gas specimen parameters affected when the specimen is not maintained under strict anaerobic conditions?

pH increases pCO2 decreases pO2 increases *Oxygen raises pH inversely lowering CO2, ruining the anaerobic conditions

An electrolyte panel usually consists of which group of tests?

sodium, potassium, chloride, CO2 (Bicarbonate) or Na, K, Cl, CO2

Osmolality

the concentration of solutes in body fluids

freezing point depression

the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

international unit (IU/L)

the quantity of enzyme required to convert one micromole of substrate per minute into products

Bone enzymes

ALP

Liver enzymes

AST, ALT, ALP, GGT

Given the following patient results, what is the calculated osmolality? Na= 139 mmol/L glucose= 130 mg/L BUN = 140mg/L

335

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

Acute viral hepatitis *AST & and ALT are liver enzymes

The following enzyme results correlate with which of the following liver disorders? AST 1752 (5-35 U/L) ALT 1659 (7-45 U/L) ALK 450 (45-100 U/L) GGT 225 (5-50 U/L)

Acute viral hepatitis *All are extremely high levels, indicating severe liver damage

ABG preanalytical considerations

Air bubbles Clots Glycolysis

The sweat chloride test is used as a screening test for what disorder?

Cystic fibrosis

What is respiratory acidosis?

A drop in blood pH due to hypoventilation; accumulation of Co2.

What is a cofactor?

A nonprotein molecule required for an enzyme's role as a catalyst

C-reactive protein (CRP)

A nonspecific protein, elevated during episodes of acute inflammation or infection.

The patient has the following serum results: Na = 130 mEq/L K = 4.9 mEq/L Cl = 107 mEq/L Glucose = 300 mg/dl Bun = 18 mg/dl What is calculated osmolality?

283

Calculate an anion gap by both formulas if: Na= 146 mEq/L K= 5 mEq/L Cl=103 mEq/L CO2=21 mEq/L

27 or (22: 22 + 5 = 7)

All of the following are liver enzymes: AST, ALT, GGT, Myoglobin and LD. T/F?

False; myoglobin not included

Method used for osmolality?

Freezing point depression

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

Gamma-glutamyl transferase (GGT)

What is the most sensitive enzyme to detect liver damage from chronic alcoholism?

Gamma-glutamyl transferase (GGT)

Osmolality Gap Calculation

Gap= (measured - calculated mOsm/Kg)

A serum specimen for Potassium received in the red top tube (no gel). If the testing is delayed, how should the specimen be handled?

centrifuge the specimen ASAP and transfer serum to another tube

Which of the following electrolytes will be elevated in the hemolyzed specimen? Na K Cl

K (potassium)

The following laboratory results are consistent with what acid-base disorder? pH 7.30 CO2 30 (35-45) pO2 68 (80-100) O2"sat. 92% (95-100%) HCO3 14 (22-26)

Metabolic acidosis *Low pH, low Bicarb (HCO3) = metabolic equal

Enzymes that produce ATP from glucose

Mg & PO4

enzyme regulation of ATPase ion pumps

Mg (magnesium)

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

Prostate *Think: P in phosphatase = P for Prostate

What are the Anion Gap formulas?

(Na + K) - (Cl + CO2 or HCO3) (ref: 10-20 mEq/L Na - (Cl + CO2 or HCO3) (ref: 7-16 mEq/L)

Enzyme Classification:

-Oxidoreductase/transferase (catalyzes transfer) -Hydrolase, lyase (breaks bonds) -Isomerase (coverts molecules) -Ligase (joins molecules)

Calculated osmolality equation

2(Na) + glucose/18 + BUN/2.8 (ref 5-10 units' difference)

What 2 plasma constituents which influence osmolality?

Albumin and Na (sodium)

Given the following results from a patient in the emergency department, what is the most likely explanation for the INCREASED osmolality? Na 140 mmol/L K 5.0 mmol/L Cl 100 mmol/L CO2 25 mmol/L GLU 90 mg/dL BUN 14.0 mg/dL Creatinine 1.1 mg/dL Osmolality 316 mOsm/Kg

Alcoholism intoxication *Osmolality high: Normal serum ranges (275-295)

The only clinically analyzed enzyme in the urine is:

Amylase *Amy urinates

Which of the following enzymes is filtered by the glomerulus and appears in the urine?

Amylase *Amy urinates

move toward the anode

Anions -

Which reactions are continuous kinetic assays?

BUN

When a myocardial infarction occurs, what is the first ENZYME to reach peak elevation?

CK *Remember Troponin is a protein

substances that speed up chemical reactions by lowering activation energy and unchanged in the end

Catalysts

move toward the cathode

Cations +

Which of the following is consistent with metabolic acidosis? Increase in pCO2 with a decreased pH Decrease in HCO3 with an increased pH Increase in HCO3 with an increased pH Decrease in HCO3 with a decreased pH

Decrease in HCO3 with a decreased pH *ROME: Metabolic Equal

Does hypoalbuminemia cause a decreased or increased anion gap?

Decreased anion gap *low albumin in a solute will cause low osmolality

Hypokalemia may be seen in which of the following conditions?

Diuretic therapy *Some diuretics cause excretion of potassium (K) following Na

When using an enzyme as a reagent, what concentration is needed and what type of enzyme kinetics are produced?

Excess; first order

blood gas analyzers perform analysis using...

ISE (indirect ion-specific electrode) (ph, PO2, PCO2)

Given the electrolyte panel results, what is the most likely explanation for these results? Na 166 mmol/L K 5.0 mmol/L Cl 111 mmol/L HCO3 (bicarb) 24 mmol/L

IV contamination

How to collect ABG

In heparinized syringe from the artery within 20 minutes (no venous blood)

When a patient is heavily intoxicated, what would the expected osmolar gap be?

Increased

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

Lactate dehydrogenase (LDH)

Which enzymes have multiple molecular forms (isoenzymes) whose clinical significance is used in diagnosis?

Lactate dehydrogenase, creatine kinase or LDH, CK

What enzyme is inhibited by hemolysis, resulting in a decreased value?

Lipase

Excess hydration Hyponatremia SIADH are examples of...

Low osmolality in serum *Hydration dilutes, so there'd be a decrease in particles & Na, causing a low osmolality in serum while inversely causing a high urine osmolality (SIADH)

Organs involved in pH compensation when changes occur

Lung & kidneys

What is a coenzyme?

Organic cofactor (vitamins & ATP)

Prostatic acid phosphatase measurement has been replaced by the measurement of what tumor marker?

PSA (no longer AHP)

Unmeasured anions in anion gap

Plasma proteins, phosphates, sulfate, citrate/organic material

Electrolyte which plays important role in heart regulation

Potassium (K)

Which of the following causes hypernatremia?

Severe burns and excessive sweating *Think: in this case, sweating rids the body of water, leaving excess Na > hyperNatremia

Hyponatremia, hypochloremia, and hypokalemia are seen in which of the following conditions?

Severe vomiting *Think: vomiting depletes body of enzymes cause hypo (low) disorders

What is the primary tissue source of creatine kinase in normal, healthy individuals?

Skeletal muscle

most abundant cation in serum

Sodium (Na)

reactant of an enzyme-catalyzed reaction (fit like lock and key with enzyme)

Substrate

Protein detectable 12 + hrs. after a myocardial infarction

Troponin

Unmeasured cations in anion gap

calcium and magnesium *Ca for Cations followed my Mg

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

Viral hepatitis

Pancreatitis enzymes

amylase and lipase

buffer systems (3)

bicarb/carbonic hemoglobin Phosphate