Med Case correlation chemistry

The potentiometric measurement of serum ions in the laboratory is demonstrated by the:

Ion-selective electrodes (ISE)

AST and ALT suggest______ ALP and GGT suggest________

liver cell injury; bile duct problems

Albumin is the most abundant protein in human plasma. It is synthesized by the liver and has which two major functions:

• Maintaining colloid osmotic pressure, which helps keep fluid inside blood vessels.

• Transporting substances such as bilirubin, calcium, hormones, and certain medications.

Which dye is commonly utilized in the dye-binding method for determining serum albumin?

Bromcresol purple (sometimes green), then absorbance measured by spec to determine albumin concentration

The renal threshold for glucose is: (do not confuse for fasting glucose)

160-180 mg/dL

A fluorometer measures light that is:

Emitted by excited electrons as they return to the ground state

The process is:

1. A molecule absorbs light at a particular wavelength.

2. Its electrons are excited to a higher energy level.

3. The electrons return to a lower energy level.

4. The molecule emits fluorescent light, typically at a longer wavelength.

Scattered light is associated with methods such as

nephelometry

The immunoglobulins (antibodies) generally migrate as:

A. Alpha-1 globulins
B. Alpha-2 globulins
C. Beta globulins
D. Gamma globulins

Gamma

Albumin_Albumin

Alpha-1_Alpha-1 antitrypsin

Alpha-2_Haptoglobin, alpha-2 macroglobulin

Beta_ Transferrin, complement C3

Which represents the light path through a spectrophotometer, beginning immediately after the light source?

hexokinase test

glucose is turned into a compound that makes NADPH; which absorbs UV light

Glucose oxidase

creates hydrogen peroxide, which reacts to make a colored compound. More glucose, more color. But certain drugs can dampen that color change (interference)

The clinical Laboratory Improvement Amendments (CLIA) of 1988 require that personnel be assessed:

annually

dilution factor formula

Dilution factor = Total volume ÷ Serum volume

if ALP and GGT were markedly high instead, what would you lean toward?

obstructive jaundice

ALP is slightly increased, ALT is markedly increased, GGT is slightly increased, AST is markedly increased, these findings are most consistent with

acute hepatitis, ALT and ALP markedly high suggest inflamed or damaged cells

_____ tube is preferred for glycated hemoglobin, or HbA1c

EDTA

(Glucose testing commonly uses serum or plasma)

What is the major site of cholesterol synthesis:

liver

In the diagnosis of myocardial infarction, which of the following tests would be produced the most sensitive and specific information

troponin and CK

In acidosis, in order to maintain electroneutrality, the chloride shift allows:

chloride to shift into the cells & HCO3 (bicarbonate) to shift out to buffer H+

In BUN enzymatic methods, urease hydrolyzes urea to form ______, which is quantitated and is directly proportional to the amount of BUN in the specimen:

ammonium

with severe kidney impairment, would BUN generally go up or down?

BUN goes up when kidneys fail to clear it. It's like trash piling up when the pickup slows. Urea isn't cleared, so BUN accumulates.

LDL calculation

To calculate LDL, use total cholesterol minus HDL minus triglycerides divided by five, all in milligrams per deciliter

At blood pH 7.40, the ratio of bicarbonate to carbonic acid is:

20:1 (acidosis is if it drops below 20)

A serum protein electrophoresis (SPE) is performed and the technologist suspects that the specimen used was plasma, not serum, because of the characteristic peak in the ____ region:

Beta region. Here's why. Plasma still has fibrinogen, and that shows up as an extra peak between beta and gamma globulins

In the creatinine clearance formula the term 1.73A is used to:

Option A

normalize clearance, making it independent of muscle mass

sodium range

135 to 145 mmol'/L (below hyponatremia. above hypernatremia)

potassium range

3.5- 5.0 mmol/L (hypokalemia, hyperkalemia)

chloride range

98-106 mmol/L (hypochloremia, hyperchloremia)

bicarbonate range

22-28 mmol/L (metabolic acidosis, metabolic alkalosis)

Question 8

A plasma sample was analyzed using ion selective electrodes and the following electrolyte results obtained:

Sodium = 141 mmol/L, Potassium = 14.0 mmol.\/L, Chloride = 113 mmol/L, Bicarbonate = 18 mmol/L

These results are consistent with a speciem that:

• Option A

  is severly lipemic

• Option B

  is slightly hemolyzed

• Option C

  needs to be diluted and reanalyzed

• Option D

  was collected in a EDTA tube

D

EDTA tubes contain potassium EDTA, so you're adding potassium from the tube itself. The analyzer can't tell the difference between the patient's potassium and the tube's potassium, so it reads falsely high. Calcium would be low due to binding

The three variables in the Henderson-Hasselbach equation are:

Option C

PH, H2CO3 (carbonic acid), HCO3 (bicarb)

Question 11

Which of the following statements apply to coenzyme system NAD/NADH:

• Option A

  as NADH is oxidized to NAD, there will be a decrease in absorbance

• Option B

  as NAD is reduced to NADH, there will be an increase in absorbance

• Option C

  the conversion of NAD to NADH is measured at 340 nm

• Option D

  340 nm is in the ultraviolet wavelength range

ALL

Question 14

Given the following information, calculate the bicarbonate to PCO2 ratio

pH = 7.57

PCO2 = 40 mm Hg

HCO3 = 36 mmol/L:

the bicarbonate-to-carbonic-acid ratio works out to thirty to one. You multiply PCO2 by 0.03 first, then divide the bicarb by that. Normal is twenty to one.

Which of the following serum results correlates best with rapid cell turnover associated with chemotherapy treatments:

• Option A

  BUN of 35 mg/dL

• Option B

  creatinine of 2.6 mg/dL

• Option C

  uric acid of 10.5 mg/dL

  Selected

• Option D

  potassium of 4.5 mmol/L

C

rapid cell breakdown releases nucleic acids that get turned into uric acid

The chemical linkage of amino acids that forms peptide bonds occurs between:

amine and carboxyl groups

Question 19

When using the glucose oxidase coupled enzymatic reaction, what is actually measured to determine the glucose concentration in serum samples:

the increase in absorbance (color change)

Urea levels are measured in blood primarily to detect:

kidney function

Transferrin and complement (C3 & C4) migrate electrophoretically as:

beta globulins

A hospitalized patient is experiencing increased neuromuscular irritability (tetany). Which of the following test results would you expect to see:

decreased ionized calcium

Because when calcium's low, the nerves and muscles become easier to trigger, so they fire too easily.

Which of the following conditions could result in respiratory acidosis:

emphysema

Poor ventilation means CO2 builds up and pH drops.

Recall renal failure causes metabolic ________ , and vomiting causes metabolic _________

acidosis; alkalosis

Calculate creatinine clearance

flow rate calculated by dividing volume in 24 hour sample by 1440 min

corrected creatinine clearance

Jaffe reaction

BUN: creatinine ration

BUN reference range

7-18 mg dL

serum creatinine range

0.8–1.4 mg/dL

creatinine clearance normal rate

120 mL/min

hyperuricemia (elevated uric acid) associated with what

gout, chronic renal disease, chemo (large numbers of cancer cells may be destroyed rapidly. When those cells break apart, they release DNA and RNA.

DNA and RNA contain purines (adenine and guanine), which are eventually broken down into uric acid.)

calculate osmolality

respiratory/metabolic pH range

7.35–7.45

pCO₂ range

35–45 mmHg

pO2 range

80–100 mmHg

HCO₃⁻ range

22–26 mmol/L

In acidosis, in order to maintain electroneutrality, the chloride shift allows:

chloride to shift into the cells & HCO₃ to shift out to buffer H⁺

anion gap equation with and without potassium

AG=(Na +K )-(Cl +HCO3) [can use CO2 in place of HCO3]

AG= Na - (Cl +HCO3)

The recommended diagnostic criteria for the fasting glucose level for the diagnosis of diabetes is

126 mg/dl

A moderatley hemolyzed serum sample will cause falsely elevated results for each of the following analytes EXCEPT:

1. Option A

   potassium

2. Option B

   phosphorous

Option C

sodium

1. Option D

   Incorrect:

   lactate dehydrogenase (LD)

sodium (mostly already outside cell)

In what form must cholesterol be for it to react with cholesterol oxidase in the enzymatic methods:

free

In the enzymatic assay, cholesterol oxidase only works on free cholesterol, meaning it's not esterified with a fatty acid. Cholesterol esterase first strips the fatty acid off, so then oxidase can act.

Question 1

Which of the following is the unit of measurement for serum enzymes:

International units (I.U.)

The lipid fraction, when elevated, which builds up in the linings of the arteries and leads to premature atherosclerosis is:

low density lipoprotein (LDL)

Which of the following methods is most specific for measuring plasma glucose:

hexokinase

Question 9

Which of the following statements are true regarding the diagnosis of acute pancreatitis:

• Option A

  serum amylase remains elevated longer than urine amylase

Option B

serum lipase is more specific than serum amylase

• Option C

  urine lipase is elevated longer than serum lipase

• Option D

  All of the above

B

urine amylase stays up longer than serum amylase and urine lipase isn’t the standard

Question 10

In the classic Cherry-Crandall procedure for the determination of this enzyme, fatty acids & glycerol are liberated from triglycerides [olive oil] and the fatty acids are titrated with NaOH:

lipase

sweat chloride test tests for

cystic fibrosis

Hypercalcemia ( Ca++) is common in which of the following disorders:

bone cancer. Think bone breakdown releasing calcium

Uric acid is a final breakdown product of:

purine

urea is a final breakdown product of:

proteins

Tumor markers