Endocrine function and haemoglobinopathies: biochemical assessment of thyroid function in children with sickle-cell disease.

Thyroid function was assessed in ninety children with homozygous sickle-cell disease (haemoglobin genotype SS) in forty-five children with heterozygous sickle-cell trait (AS) and in 162 control children with haemoglobin genotype AA. Serum levels of thyroxine, the in vitro triiodothyronine resin uptake and the calculated index of 'free thyroxine' were not significantly different in the three groups. The distribution of individual thyrotropin (TSH) values showed that only 11% of the HbSS subjects had values below the 95% confidence limits for the HbAA controls. However, the mean level of TSH was significantly lower in the HbSS than the other two groups of children.