Excessive iodine intake during pregnancy in Somali refugees

Abstract

Iodine deficiency and excess are both associated with adverse health consequences, with fetuses, children and pregnant women being most vulnerable to the devastating effects of severe deficiency. It is often assumed that the iodine status of a population if displaced or in a remote or emergency situation is low. However, there is little evidence available to support this assumption, especially among long-term food-aid-dependent pregnant women. An effectiveness trial of a prenatal multiple-micronutrient supplement that contained 150 µg day(-1) iodine was conducted in two refugee camps in the North Eastern Province of Kenya in 2002. Urinary iodine concentration (UIC) was measured in a subsample of pregnant women attending antenatal care in Dagahaley (control camp) (n = 74) and Ifo (intervention camp) (n = 63). There was no significant difference in median UIC between the two camps (P = 0.118). The combined median UIC was 730 µg L(-1) (interquartile range, 780) (5.77 µmol L(-1)) and exceeded the upper safe limit of 500 µg L(-1) (3.95 µmol L(-1)) for pregnant women (P < 0.001), indicating excessive iodine intake. About 20% of the study subjects had 'more than adequate' urinary iodine, while over 71% had excessive UIC. Salt iodine content varied between 5.1 and 80.1 ppm in the five market salt samples analysed. In conclusion, excessive iodine intake was evident in the Dadaab refugee camps. Further research needs to be conducted to investigate the source of excess iodine, to determine the measures needed to address excessive iodine intake and to reconsider the World Health Organization/World Food Programme/United Nations Children's Fund guidance on supplementation of vulnerable groups in emergencies.

Consequences of excess iodine

“…A study published in 2012 reported that the median UIC (730 μg/l) of the populations of two Somali refugee camps in Kenya who were receiving iodine supplementation were in the range consistent with excessive iodine intake. 19 In a study of >200 Chinese adults, subclinical hypothyroidism was more common in those supplemented with a 400 μg iodine tablet than in those given placebo. 20 These findings are similar to the results of other studies in Denmark 21 and New Zealand, 22 which also showed an increased prevalence of transient hyperthyroidism.…”

Effects of Increased Iodine Intake on Thyroid Disorders

“…The upper limit of acceptable iodine intake in pregnancy is controversial. Iodine excess during pregnancy existed in Somalia [ 45 ], Japan and other countries. The fetal thyroid does not acquire the capacity to suppress the acute Wolff-Chaikoff effect until approximately 36 weeks of gestation [ 46 ].…”

Risks of excess iodine intake in Ghana: current situation, challenges, and lessons for the future

“…However, permanent metabolic effects of excess iodine intake could occur if the iodine source is not detected and discontinued . Excess iodine intake has been reported in China, and among African refugees in Sudan, Algeria, and Somalia, mainly associated with drinking water and the use of iodized salt …”

“…However, permanent metabolic effects of excess iodine intake could occur if the iodine source is not detected and discontinued. 19 Excess iodine intake has been reported in China, 20 and among African refugees in Sudan, 21 Algeria, 22 and Somalia, 23,24 mainly associated with drinking water and the use of iodized salt. 25,26 The Universal Salt Iodization (USI) program in Ghana mandates that all salt produced, imported, distributed, and marketed in Ghana should meet the set standards of iodine content in salt, quality, iodization, and packaging for human and animal consumption.…”