Formulas/calculations

Question 1

Concentration of NaCl solution that is isotonic

Answer 1

0.85%
Prevents RBC’s from crenating or lysing.

Question 2

Sensitivity

Answer 2

[True positives/(false negatives + true positives)]x100

Question 3

Specificity

Answer 3

[True negatives/(false positives + true negatives)]x100

Question 4

MCHC
Mean cell hemoglobin concentration

Answer 4

(Hb/Hct)x100

Units: g/dL
Reference range: 33-37 g/dL

Question 5

MCH
Mean cell hemoglobin

Answer 5

(Hb/RBC count)x10

Units:pg
Reference range: 26-34 pg

Question 6

MCV
Mean cell volume

Answer 6

(Hct/RBC count)x10

Units:fL
Reference range: 80-100

Question 7

Anion gap

Answer 7

Difference between negatively charged ions (Cl, bicarbonate CO2) and positively charged ions (K, Na). Positive - Negative

AG = (K + Na) - (Cl + CO2)

Too low, means blood is too basic. Metabolic Alkalosis.
Too high means blood is too acidic. Metabolic Acidosis.

Question 8

Total cholesterol

Answer 8

TC = LDL + HDL + VLDL

VLDL = TG/5

Ideal: TC < 200 mg/dL
HDL is better than LDL which is better than VLDL

Question 9

AST:ALT

Aspartate transaminase:alanine transaminase

Answer 9

Should be <1

In alcoholic liver disease the ratio is >1 in 92% of patients and >2 in 70%