Impact evaluation of efforts to eliminate iodine deficiency disorders in Nigeria.

OBJECTIVE : The objective of the present review is to assess the impact of universal salt iodisation in Nigeria during the last five years, with reference to some of the sentinel sites studied previously during a 1995 multi-centre study. DESIGN, SETTING AND SUBJECTS : The method of goitre classification by palpation was employed using the new internationally accepted method in which the classification is simply graded as 0, 1 or 2. The multistage random sampling method was used and states and local government areas were already selected by virtue of their known status for iodine deficiency disorders (IDD). Schools were randomly chosen in each local government area and children aged 8-12 years in each school were determined. A percentage of the children was then included in the study to give a sample size greater than the minimum number allotted to the school. A total of 2372 schoolchildren (1420 males and 952 females) in 11 local government areas were examined; urine samples were collected from 537 children and analysed for urinary excretion of iodine. The method known as the Sandell-Kolthoff reaction was adopted, in which the iodide in the urine samples catalyses the reduction of ceric ammonium sulphate (yellow colour) to the cerous form (colourless) in the presence of arsenious acid. The degree of reduction in colour intensity of the yellow ceric ammonium sulphate is proportional to the iodine content in the urine sample. RESULTS : The results from this study show that the median urinary iodine excretion for this sampled population in Nigeria, drawn mostly from IDD-endemic areas, is 14.65 microgram dl-1 with a mean value of 13.39 microgram dl-1. CONCLUSION : This finding would suggest that Nigeria, in general terms, has achieved the goal of universal salt iodisation and should now focus its attention on constant monitoring in order to sustain this iodisation level.