Hematologic changes during sexual maturation. Why do black adolescents have low hemoglobin concentrations?

Haematological and Biochemical Reference Values for Healthy Population of Maferinyah Rural Community in Guinea

Guinea's reference ranges for biological parameters rely on those of Caucasian values. Variability in reference ranges according to the context is well-documented. We conducted this study for the purpose of future malaria clinical trials that assess the efficacy and safety of malaria drugs. A repeated cross-sectional study was carried out, in an apparently healthy cohort population. Surveys took place in Maferinyah rural community, which is located at 75 km from the capital. The 2.5^th and 97.5^th percentiles were determined nonparametrically and stood for reference intervals. Reference values were determined separately for males and females according to ranges of age (6-10 years of age; 11-15 years of age; 16-45 years of age). Differences between genders were tested using the Mann-Whitney test, while the Friedman test was performed to test differences within each gender group according to the seasons. A total of 450 volunteers were enrolled. The median age was 13. Males 16-45 years of age had significantly higher hematologic and biochemical values compared to a female of the same age (for hematological parameters: Mean Cell Hemoglobin Concentration MCHC p ≤ 0.001, Platelets p ≤ 0.001, monocytes p = 0.0305, eosinophils p = 0.0225; for biochemical parameters: Aspartate aminotransferase AST p ≤ 0.001, Alanine Aminotransferase ALT p ≤ 0.001, creatinine p ≤ 0.001). We noticed significant seasonal variations for all the biochemical parameters and some hematologic parameters (Mean Corpuscular Hemoglobin MCH, MCHC, Mean Cell volume). This is the first study establishing hematologic and biochemical parameters in Guinea. These findings provide a useful guide for the clinical researchers and care providers. Studies on large scale and in different settings would be also desirable.

Establishment of haematological and immunological reference values for healthy Tanzanian children in Kilimanjaro Region

OBJECTIVE

To determine the normal haematological and immunological reference intervals for healthy Tanzanian children.

METHODS

We analysed data from 655 HIV-seronegative, healthy children from 1 month to 18 years of age from the Kilimanjaro Region of Tanzania for this cross-sectional study. Median and 95% reference ranges were determined for haematological and immunological parameters and analysed by age cohorts, and by gender for adolescents.

RESULTS

Median haemoglobin (Hb) and haematocrit (Hct) for all age groups were higher than established East African reference intervals. Compared to U.S. intervals, reference ranges encompassed lower values for Hb, Hct, mean corpuscular volume, and platelets. Applying the U.S. National Institute of Health Division of AIDS (DAIDS) adverse event grading criteria commonly used in clinical trials to the reference range participants, 128 (21%) of 619 children would be classified as having an adverse event related to Hb level. CD4-positive T-lymphocyte absolute counts declined significantly with increasing age (P < 0.0001). For those aged under five years, CD4-positive T-lymphocyte percentages are lower than established developed country medians.

CONCLUSIONS

Country-specific reference ranges are needed for defining normal laboratory parameters among children in Africa. Knowledge of appropriate reference intervals is critical not only for providing optimal clinical care, but also for enrolling children in medical research. Knowledge of normal CD4-positive T-lymphocyte parameters in this population is especially important for guiding the practice of HIV medicine in Tanzania.

Impact of race and gestational age on red blood cell indices in very low birth weight infants

BACKGROUND

Normative data for hematologic values in the very low birth weight infants are limited and inconsistent, with the reported mean hematocrit (HCT) in these infants ranging from 43.5% to 60%. No data are available on the effect of race.

OBJECTIVES

To establish normative data for hemoglobin (Hb) and HCT by arterial sampling obtained during the first 3 hours after birth in black and white premature infants </=31 weeks of gestation.

METHODS

Retrospective chart review of all infants </= 31 weeks of gestation born between June 1994 and October 1998.

INCLUSION CRITERIA

infant </=31 weeks of gestation who had an arterial blood sample obtained in the first 3 hours after birth.

EXCLUSION CRITERIA

infants were excluded if they had any medical condition that may affect the red blood cell indices (eg, twin-to-twin transfusion or fetomaternal hemorrhage).

RESULTS

Of 428 infants, 188 who met both inclusion and exclusion criteria were classified into 3 gestational age groups: group 1 = 23 to 25 weeks of gestation (n = 40); group 2 = 26 to 28 weeks (n = 60); and group 3 = 29 to 31 weeks (n = 88). There were statistically significant differences between groups 1 and 3 in HCT, Hb, mean corpuscular Hb (MCH), and mean corpuscular volume (MCV). No differences in HCT and Hb values were noted in relation to sex, mode of delivery, multiple gestation, antenatal steroids, or maternal smoking. In group 3, the mean Hb, HCT, and MCV values were higher in white infants than in black infants (16.7 +/- 1.6 g/dL vs 15.4 +/- 1. 7 g/dL; 50.0 +/- 5.0 vs 45.5 +/- 4.6; and 112 +/- 5 fL vs 107 +/- 8 fL, respectively).

CONCLUSIONS

Hb, HCT, and MCH values are described for premature infants </=31 weeks of gestation born in North America. Hb and HCT increased, whereas MCV decreased with gestational age. Hb, HCT, and MCV values are statistically higher in white infants than in black infants.