Household Water Is the Main Source of Iodine Consumption among Women in Hargeisa, Somaliland: A Cross-Sectional Study

Abstract

Background: Iodine status surveys of women in Somaliland present widely conflicting results. Previous research indicates elevated concentrations of iodine (IQR 18-72 μg/L) in groundwater used for drinking and cooking, but the relation with iodine intake is not well characterized.

Objectives: We aimed to investigate the contributions of household water iodine concentration (WIC), breastfeeding, total fluid intake, hydration levels, and urine volume on urinary iodine concentration (UIC) and excretion (UIE) over a 24-h period and to define iodine status from iodine intake estimates and median UIC, normalized to a mean urine volume of 1.38 L/d (hydration adjusted).

Methods: The study sample comprised 118 nonpregnant, healthy women aged 15-69 y. All participants resided in Hargeisa, and 27 were breastfeeding. Data collection consisted of a 24-h urine collection, a 24-h fluid intake diary, a beverage frequency questionnaire, and a structured recall interview. We measured UIC and WIC in all urine and in 49 household water samples using the Sandell-Kolthoff reaction.

Results: WIC ranged between 3 and 188 μg/L, with significant median differences across the water sources and city districts (P < 0.003). Nonbreastfeeding women were borderline iodine sufficient [hydration-adjusted median urinary iodine concentration (mUIC) 109 μg/L; 95% CI: 97, 121 μg/L], whereas breastfeeding women showed a mild iodine deficiency (73 μg/L; 95% CI: 54, 90 μg/L). There were strong correlations (ρ: 0.50-0.69, P = 0.001) between WIC and UIC, with iodine from household water contributing more than one-half of the total iodine intake. Multivariate regression showed hydration and breastfeeding status to be the main predictors of UIC.

Conclusions: Iodine from household water is the main contributor to total iodine intake among women in Hargeisa, Somaliland. Variation in female hydration and spatial and temporal WIC may explain diverging mUIC between studies. Water sources at the extremes of low and high iodine concentrations increase the risk of subpopulations with insufficient or more than adequate iodine intake.

Keywords: 24-h urinary iodine excretion; Iodine; Somaliland; breastfeeding; drinking water; total fluid intake; urinary iodine concentration; women.

FIGURE 1

Recruitment outcome in women aged 15–69 y, with participants who were dropouts, excluded, and lost to follow-up. CKD, chronic kidney disease; MCH, mother-child health clinic.

FIGURE 2

Comparison of distributions of UIC and adjusted UIC in 118 women in Hargeisa. The solid line shows median UIC of 125 μg/L, and the dashed line indicates median adjusted UIC (UIE/1.38 L) of 102 μg/L, independent-samples Mann-Whitney U test, n = 236, P = 0.002. The calculations assume that 150 μg/d of iodine intake equals a UIC of 100 μg/L with 92% of iodine ingestion excreted in urine. UIC, urinary iodine concentration; UIE, urinary iodine excretion.