Efficacy of oral iodised oil is associated with anthropometric status in severely iodine-deficient schoolchildren in rural Malawi

The effect of anthropometric status on the efficacy of an oral supplement o f iodised oil (1 ml Lipiodol Ultrafluide, 490 mg I; Laboratoire Guerbet, Au lnay-sous-Bois, France) was examined in 8-10-year-old schoolchildren (n 197 ) of Ntcheu, a severely I-deficient district of Malawi. The study was a con trolled trial using the I concentration of casual urine samples to monitor the I status. The median urinary I concentration increased from 0 . 15 mu m ol/l at baseline (51 . 3 % of children < 0 . 16 mu mol/l, 89 . 7 % < 0 . 40 mu mol/l, 95 . 7 % 0 . 79 mu mol/l) to 0 . 32 mu mol/l at 40 weeks (29 . 1 % of the children < 0 . 16 mu mol/l, 71 . 0 % < 0 . 40 mu mol/l, 96 . 1 % < 0 . 79 mu mol/l) while the total goitre prevalence fell from 63 % to 21 % . Variables of efficacy were estimated from a hyperbolic function describin g the longitudinal pattern of urinary I excretion after the dose. The I ret ention and I elimination rate, and the periods of protection from mild (< 0 . 79 mu mol/l) or moderate (< 0 . 16 mu mol/l) I deficiency were obtained for groups of children with differing anthropometric status at baseline. In itial height-for-age and mid upper-arm circumference were not significantly related to efficacy. However, both the I retention and I elimination rate were reduced in children with lower initial weight-for-height. Children wit h lower skinfold thickness at baseline also had reduced I retention, which resulted in shorter protection periods from recurrent moderate and mild I d eficiency. The efficacy of the oral iodised-oil supplement was not related to changes in anthropometric status during follow-up, nor was it related to the consumption of a food supplement of 1610kJ immediately before the iodi sed-oil dose. Very low (< 0 . 16 mu mol/l) urinary I concentration, and the presence of goitre at baseline were both associated with higher I retentio n and elimination rate. Children with goitre at baseline were found to have a prolonged duration of protection against recurrent moderate I deficiency . We conclude that in apparently healthy schoolchildren in I-deficient area s, general anthropometric status has a little influence on the efficacy of oral iodised oil for correcting I deficiency.