Variable | Age 2 months (n=119) | Age 5 months (n=93) | Age 13 months (n=42) | p Values | |||||
---|---|---|---|---|---|---|---|---|---|
Mean (SD) | 95% Range | Mean (SD) | 95% Range | Mean (SD) | 95% Range | 2–5 months | 2–13 months | 5–13 months | |
Hb (g/L) | 108 (9) | 91–125 | 115 (7) | 101–129 | 119 (7) | 105–133 | <0.001 | <0.001 | <0.01 |
RBC (×1012/L) | 3.52 (0.29) | 2.95–4.09 | 4.33 (0.28) | 3.79–4.87 | 4.51 (0.30) | 3.92–5.10 | <0.001 | <0.001 | <0.01 |
Hct (l/L) | 0.322 (0.027) | 0.268–0.376 | 0.340 (0.022) | 0.297–0.383 | 0.352 (0.020) | 0.312–0.391 | <0.001 | <0.001 | <0.01 |
MCV (fl) | 91.4 (3.4) | 84.7–98.1 | 78.7 (2.8) | 73.3–84.1 | 78.2 (2.8) | 72.8–83.6 | <0.001 | <0.001 | NS |
MCH (pg) | 30.9 (1.2) | 28.6–33.1 | 26.6 (1.1) | 24.5–28.7 | 26.5 (1.1) | 24.3–28.7 | <0.001 | <0.001 | NS |
MCHC (g/L) | 338 (9) | 321–355 | 338 (7) | 323–352 | 339 (7) | 325–352 | NS | NS | NS |
RDW (%) | 13.9 (0.9) | 12.1–15.7 | 12.1 (0.8) | 10.5–13.8 | 12.9 (0.6) | 11.6–14.1* | <0.001 | <0.001 | <0.001 |
Reticulocytes (×109/L) | 122 (49) | 63–235 | 71(23) | 41–124 | 89 (27) | 36–142 | <0.001 | <0.001 | <0.01 |
ZPP (µmol/mol haem) | 65 (23) | 36–116 | 58 (17) | 25–91 | 42 (8) | 27–57 | <0.01 | <0.001 | <0.001 |
Platelets (×109/L) | 437 (113) | 216–658 | 377 (97) | 241–591 | 332 (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.