Table 1

Mean (SD) and 95% reference intervals for red blood cell variables and platelet counts at 2, 5 and 13 months of age

VariableAge 2 months (n=119)Age 5 months (n=93)Age 13 months (n=42)p Values
Mean (SD)95% RangeMean (SD)95% RangeMean (SD)95% Range2–5 months2–13 months5–13 months
Hb (g/L)108 (9)91–125115 (7)101–129119 (7)105–133<0.001<0.001<0.01
RBC (×1012/L)3.52 (0.29)2.95–4.094.33 (0.28)3.79–4.874.51 (0.30)3.92–5.10<0.001<0.001<0.01
Hct (l/L)0.322 (0.027)0.268–0.3760.340 (0.022)0.297–0.3830.352 (0.020)0.312–0.391<0.001<0.001<0.01
MCV (fl)91.4 (3.4)84.7–98.178.7 (2.8)73.3–84.178.2 (2.8)72.8–83.6<0.001<0.001NS
MCH (pg)30.9 (1.2)28.6–33.126.6 (1.1)24.5–28.726.5 (1.1)24.3–28.7<0.001<0.001NS
MCHC (g/L)338 (9)321–355338 (7)323–352339 (7)325–352NSNSNS
RDW (%)13.9 (0.9)12.1–15.712.1 (0.8)10.5–13.812.9 (0.6)11.6–14.1*<0.001<0.001<0.001
Reticulocytes (×109/L)122 (49)63–23571(23)41–12489 (27)36–142<0.001<0.001<0.01
ZPP (µmol/mol haem)65 (23)36–11658 (17)25–9142 (8)27–57<0.01<0.001<0.001
Platelets (×109/L)437 (113)216–658377 (97)241–591332 (63)209–455<0.001<0.001<0.001
  • The following values were missing: five zinc protoporphyrin (ZPP) values at age 2 months, one platelet, one reticulocyte and six ZPP values at age 5 months and one platelet value at age 13 months.

  • *Subjects with red cell distribution width (RDW) values >13.9% were excluded at 13 months of age. The 95% range derived from the remaining values produced an upper limit of 14.1%. Hct, haematocrit; Hb, haemoglobin; MCH, mean cell haemoglobin; MCHC, mean cell haemoglobin concentration; MCV, mean cell volume; NS, not significant; RBC, red blood cell count.