Hematology Calculationscontinued Hematology Review 340
FORMULA EXAMPLE CALCULATION
Rules of Three:
RBC ¥3 = HGB ±0.5
HGB ¥3 = HCT ±3%
Manual Cell Count:
Cells/mm^3 (μL) = # cells counted ¥depth factor
(always 10) ¥reciprocal of dilution ¥reciprocal of
area counted (mm^2 )
Absolute WBC = total WBC ¥relative count
(% from differential)
Corrected WBC =
uncorrected WBC 100
+ NRBCs per 100 WBCs
¥
100
What should the HGB be if the RBC is 4.1 ¥ 1012 /L?
HGB = 4.1 ¥3 = 12.3 ±0.5 = 11.8–12.8 g/dL
What should the HCT be if HGB is 12.3 g/dL?
HCT = 12.3 ¥ 3 =36.9 ± 3 =33.9%–39.9%
Calculate the CSF WBC count if 18 WBCs are counted in 9 mm^2 on 1 side of a
Neubauer hemacytometer, using undiluted CSF.
WBCs/μL = 18 ¥ 10 ¥ 1 ¥1/9 = 20
Calculate the absolute lymphocyte count if the total WBC is 10 ¥ 109 /L & there are
70% lymphocytes.
Absolute count = 10 ¥0.70 = 7 ¥ 109 /L
The automated hematology analyzer reports a WBC of 30 ¥ 109 /L. The technologist
counts 115 NRBCs per 100 WBCs while performing the differential. What is the cor-
rected WBC?
Corrected WBC =^30100 = 14 ¥ 109 /L
+ 115
¥
100
