Author(s): Chinyanga E, Chidede O
OBJECTIVE: To measure serum thyrotropin (TSH), and free thyroxine concentrations in newborns delivered in areas with differing degrees of iodine deficiency, (prior to the salt iodization programme), and to use these biochemical indices to assess the current status of thyroid function in the group. DESIGN: Cross sectional. SETTING: Chemical Pathology, University of Zimbabwe, Medical School. Radio-immunoassay laboratory, Parirenyatwa Hospital. SUBJECTS: 500 healthy full term newborns, aged two to four days old, weighing not less than 2.5 kg. MAIN OUTCOME MEASURES: Thyroid hormone status of newborns. RESULTS: The mean serum FT4 level was found to be slightly but significantly different between the newborns from Harare region, (low goitre prevalent area), and Wedza district (moderate to severe goitre prevalent area). Although there was a trend in the distribution of TSH to higher values in the moderate to severe goitre prevalent areas, the differences were statistically non significant, p = 0.175. The median TSH value in the newborns was 4 microU/ml. TSH values were below 10 microU/ml in 90%, between 10.1 and 20 microU/ml in 9%, and between 20.1 and 32 microU/ml in 1% of the cases. No sex related differences were observed in either the TSH nor the FT4 values of the newborns. CONCLUSION: This study demonstrates that the iodine supplementation programme has been successful, but further monitoring is necessary to ensure complete supplementation throughout the country and to guard against hyperthyroidism which is known to occur during iodine supplementation programmes.