ASCP Calculations

Dilution Formula

Sample Volume / (Sample Volume + Dilution Volume)

Concentration Calculations

(C1)(V1) = (C2)(V2)

Henderson-Hasselbalch equation

pH = pKa + log([A-]/[HA])
A- is the conjugate base and [HA] is the acid concentration.

Anion Gap

It is calculated using the formula: Anion Gap = [Na]+ [K] - (Cl- + HCO3-).

The Anion Gap is a calculation used to identify the causes of metabolic acidosis by measuring the difference between the concentrations of serum cations and anions.

LDL Cholesterol

Total cholesterol - (HDL + Triglycerides/5)

Hemacytometer

#cells/mm³ = [#cells counted x dilution factor] / [number of squares x (area of squares x 0.1)]

Calculation of the number of cells/ml

Beer’s law

A = εcl, where A is absorbance, ε is the molar absorptivity, c is concentration, and l is the path length.

Absorbance

2-log%TThe measure of the amount of light absorbed by a sample, calculated as 2 minus the logarithm of the transmittance percentage.

Albumin (A)/Globulin (G) ration

A/G ratio is calculated by Albumin/(Total Protein-Albumin)

Creatinine Clearance

Urine creatinine mg/dL (U) x Urine Volume mL (V) / Serum creatinine mg/dL (S) x Collection time min

(U x V) / (S x T)

Transferrin saturation

(serum iron/TIBC) x 100

Osmolality

1.86 (Na) + (glucose)/18 + (BUN)/2.8

Vials of RhIg

(% fetal cells x 50) / 30

Find % fetal cells through Kleihauer-Betke Acid Elution test
% fetal cells = (# of fetal cells conted /1000 adult cells counted) x 100

MCV (fL)

Hct/RBC count x 10

MCH (pg)

Hgb/RBC count x 10

MCHC (g/dL)

Hgb/Hct x 100

24 hour Urine Protein Calculation

Protein concentration (mg/dL) x 1 dl/100 mL x Urine volume (mL) / 24 hrs

INR Internation Normalized Ratio

Patient’s PT value / Laboratory’s mean PT value

Mean

Sum of every value / total amount of values

∑x / n 

i.e Mean of 1,2,3,4,5,6,7,8,9,10 → (1+2+3+4+5+6+7+8+9+10) / 10 = 5.5

Standard Deviation and Variance

Variance from the mean for each data point

stdev (σ) = √[ Σ (xi - μ)² / N ]

xi: each individual data point
μ: mean

N: total number of data points

Variance: stdev²

Coefficient of Variance

Compare the relative precision (reproducibility) of two set of values

CV(%) = (sd/mean) x100

Molarity

M = n/V

n = number of moles of compound (use molar mass)

V = liters of solution