Iodine supplementation: comparison of oral or intramuscular iodized oil with oral potassium iodide. A controlled trial in Zaire

Abstract

A community-based controlled trial of iodine supplementation comparing oral or intramuscular iodized oil with oral potassium iodide has been carried out in 23 severely iodine-deficient villages in Eastern Zaire. The overall goitre prevalence in the population (n = 5999) was 61% and mean urinary iodine excretion in sample of 57 women 10.9 (SD 6.8) micrograms/g creatinine. All adults in three groups of four villages were given single doses of potassium iodide of 0.5 g, 1.0 g, and 2.0 g respectively. A fourth group was given oral iodized oil (2 ml) and a fifth placebo-treated. A further three villages were given intramuscular iodized oil (2 ml). The effectiveness of supplementation was assessed by measurements of bloodspot thyroxine (T4) concentration in women of reproductive age in the villages. The effects of iodide were small and inconsistent. Eight months after supplementation with oral iodized oil the distribution of T4 concentrations was similar to that seen with intramuscular oil. We conclude that oral iodized oil is an effective alternative to injected oil and would be feasible for iodine supplementation in remote areas with untrained people.

PIP: Iodine deficiency is a severe problem in Eastern Zaire, especially in women of childbearing age, and there is an urgent need for a simple method of oral iodine prophylaxis. In each of 23 villages, with a total population of 7174, 35 women of reproductive age were tested for blood thyroxine content. 20 of the 23 villages were then divided into 5 groups. In each of 3 villages everyone over 10 was given .5 gm, 1 gm, and 2 gm respectively of potassium iodide in a single dose. In the 4th group the subjects were given a 2 ml oral dose of iodized oil. The 5th group was given a placebo. In each of the 3 remaining villages the subjects were given 2 ml intramuscular iodized oil. Effectiveness of treatment was measured after 4 and 8 months to assess treatment by measuring reduction in size of goiters and measurements of bloodspot thyroxine concentrations. Goiter reduction was slight, but blood thyroxine levels were significantly elevated in subjects treated with either oral or intramuscular iodized oil. It is concluded that large-scale supplementation with oral iodized oil would be both effective and feasible.