Haematological indices in normal negro children: a Jamaican cohort from birth to five years

Haematological indices, including total haemoglobin, mean cell haemoglobin concentration, red cell count, mean cell volume, mean cell haemoglobin, reticulocytes, and serum iron values, in a cohort of 243 randomly selected Negro children with normal haemoglobin genotype, followed from birth to 5 years, are reported. Total haemoglobin fell rapidly from high levels at birth to a plateau at 2-6 months, a secondary fall occurred after 6 months and a gradual increase after 18 months. The red cell count also fell rapidly, but increased after 2 months to a plateau and then slowly declined from age 1-5. Mean cell volume and mean cell haemoglobin fell continously from birth to the lowest values at 15 months and then progressively increased to the age of 5 years. Serum iron levels were low at one year of age (mean 9.7 mumol/1) increasing slowly by age 4 and sharply by age 5. Mean cell haemoglobin concentration fell gradually to 1-1 1/2 years and then increased progressively to age 5. Values for Hb, MCHC, MCV, and MCH were consistently and often significantly lower in males before the age of 2 years, compatible with greater depletion of iron stores. Serum iron values were generally lower in males but there was no sex difference at one year when highly significant differences in Hb, MCHC, MCV, and MCH occurred. The cause of sex differences in early haematological development is currently unclear (AU)

The determinants of irreversible sickled cells in homozygous sickle cell disease

The relationship between the irreversible sickled cell (ISC) count and other haematological parameters has been investigated. Positive correlations occurred with MCH, MCHC, and with two expressions of intracellular Hb S content. Since the ISC has a high MCHC, the positive correlations with MCHC and with factors derived from the MCHC may be difficult to evaluate. Negative correlations occurred with total haemoglobin and Hb F. The MCHC was found to affect the relationship between HbF and ISC count, a low MCHC being associated with, and probably determining, lower ISC counts at any level of Hb F. It is proposed that a low MCHC may inhibit ISC formation and the practical implications of this are discussed (AU)

The interaction of alpha thalassaemia with SS disease

A group of patients with SS disease with red cell indices and Hb A2 levels intermediate between those of SS disease and sickle cell-beta o thalassaemia has been described. Globin chain synthesis in 20 of these subjects selected on the basis of low MCV values gave alpha/non-alpha chain ratios in the alpha thalassaemia range (0.62-0.94) compared to 20 age sex matched controls. The AS parents of these subjects with low MCV showed a greater prevalence of low Hb S concentrations (a feature of the interaction of alpha thalassaemia with the sickle cell trait) compared to controls. These data suggest that this group may represent a subpopulation of SS disease resulting from the interaction with alpha thalassaemia. (AU)