Iodine status in western Kenya: a community-based cross-sectional survey of urinary and drinking water iodineconcentrations

Abstract

Spot urinary iodine concentrations (UIC)are presented for 248 individuals from western Kenya with paired drinking water collected between 2016and 2018. The median UIC was 271lgL-1, ranging from 9 to 3146lgL-1, unadjusted for hydration status/dilution. From these data, 12% were potentially iodine deficient (\100lgL-1), whilst 44% were considered to have an excess iodine intake([300lgL-1). The application of hydration status/urinary dilution correction methods was evaluated forUICs, using creatinine, osmolality and specific gravity. The use of specific gravity correction for spot urine samples to account for hydration status/urinary dilution presents a practical approach for studies with limited budgets, rather than relying on unadjusted UICs, 24 h sampling, use of significantly large samplesize in a cross-sectional study and other reportedmeasures to smooth out the urinary dilution effect.Urinary corrections did influence boundary assess-ment for deficiency–sufficiency–excess for this group of participants, ranging from 31 to 44% having excess iodine intake, albeit for a study of this size. However,comparison of the correction methods did highlight that 22% of the variation in UICs was due to urinary dilution, highlighting the need for such correction,although creatinine performed poorly, yet specific gravity as a low-cost method was comparable to osmolality corrections as the often stated ‘goldstandard’ metric for urinary concentration. Paired drinking water samples contained a median iodine concentration of 3.2lgL-1(0.2–304.1lgL-1). A weak correlation was observed between UIC and water-I concentrations (R= 0.11).