Maternal and neonatal thyroid status in Saki, Nigeria

The influence of inadequate iodine intake on maternal and neonatal thyroid status in Saki, a locality known to have environmental iodine deficiency and located within the goitre belt of Southwestern Nigeria was investigated. One hundred and five (105) subjects and ninety (90) controls from Ibadan were recruited into the study. All subjects were apparently healthy with at least thirty-seven (37) completed weeks of gestation. Each subject was assessed for goitre and blood sample obtained by venepuncture for thyroid function tests before onset of labour. Spot urine samples were also obtained from the mothers at the time of examination for urinary iodine estimation. At delivery, cord blood samples were obtained from the babies for thyroid function tests. The mean maternal urinary iodine excretion was significantly less in Saki when compared with Ibadan (144.76 +/- 14.68 vs 213.36 +/- 9.89 ug/L P < 0.01). Maternal total goitre rates (TGR) were 46.8% and 2.2%, while maternal visible goitre rates (VGR) were 26.6% and 1.1% in Saki and Ibadan, respectively. Maternal mean plasma total T3 and total T4 were relatively lower in Saki as compared to Ibadan, though the differences were not statistically significant. Mean maternal plasma TSH in Saki was slightly above our laboratory reference interval (0.3-5.0 mU/L) and higher than the level seen in Ibadan mothers (6.54 +/- 1.58 vs 4.18 +/- 1.37 mU/L,), though the difference was also not statistically significant. Mean neonatal total T3 and T4 were lower in Saki when compared to Ibadan, but the differences were not statistically significant. The mean neonatal plasma TSH in Saki was above the adult reference interval and significantly higher than the level seen in Ibadan (9.82 +/- 1.64 vs 4.18 +/- 1.17 mU/L, P < 0.05). The incidence of neonatal chemical hypothyroidism (NCH) in Saki was 14.7 per 1000 babies. No case of NCH was seen in Ibadan. These results suggest environmental iodine deficiency and relative chemical hypothyroidism of mothers and neonates in Saki when compared to mothers and noenates from non-iodine deficient areas.