Are We Missing Hypothyroidism among Children with Sickle Cell Anaemia?

Background: Children with sickle cell anaemia have been reported to have potential risk of hypothyroidism from chronic blood transfusions and probable thyroid tissue ischaemia. However, few studies on hypothyroidism status of children with sickle cell anaemia in Nigeria are available. The objective of this study was to determine the prevalence of hypothyroidism among children with sickle cell anaemia.

Methods: A cross sectional study that assayed the thyroid hormones and thyroid stimulating hormone (TSH) of 71 children with sickle cell anaemia was conducted at Olabisi Onabanjo University Teaching Hospital Sagamu. Using age appropriate hormonal reference values, the subjects were classified into subclinical, primary and secondary hypothyroidism.

Results: The mean serum TSH, Free T3, and Free T4 were comparable irrespective of age category (p > 0.05). No subject was identified to have low TSH value while 7.0% had high TSH value. Low free T3 was identified in 1.4% and 8.5% had high free T3 values. Low free T3 and free T4 were seen in 11.3% each of the subjects. The overall prevalence of primary, secondary and subclinical hypothyroidism was 0%, 0% and 4.2%, respectively.

Conclusion: Sub-clinical hypothyroidism does occur in Nigerian children with sickle cell anaemia. Routine screening for hypothyroidism is advocated in all children with sickle cell anaemia.