TOPLINE:

Inadequate dietary iodine intake was more common in kidney transplant recipients (KTRs) than in healthy control individuals, particularly among women. Among female KTRs, inadequate iodine intake was associated with an approximately threefold increased risk for mortality.

METHODOLOGY:

• Researchers conducted this study to assess whether inadequate dietary iodine intake and low 24-hour urinary iodine excretion were associated with an increased risk for mortality among adult KTRs, with a focus on sex-specific differences.
• They included 624 adult KTRs (mean age, 53 years; 43% women) with a functioning allograft from a cohort study in Netherlands and compared them with 214 healthy control individuals.
• Clinical, demographic, and transplantation-related details were obtained from electronic patient records.
• Iodine status was assessed using 24-hour urinary iodine excretion; inadequate iodine intake was defined as a 24-hour urinary iodine excretion of less than 135 μg/d.
• Participants were followed up for a median of 5.6 years, during which 136 (22%) KTRs died, including 54 (20%) women and 82 (23%) men.

TAKEAWAY:

• Among women, the KTR group had a significantly higher prevalence of inadequate iodine intake (24% vs 6%) and lower levels of urinary iodine excretion (173 vs 265 μmol/24 h) than the control group; similar trends were observed among men (14% vs 6% and 211 vs 302 μmol/24 h).
• In female KTRs, inadequate iodine intake (hazard ratio [HR], 3.16; P < .001) and lower levels of urinary iodine excretion (HR per halving, 1.89; P < .001) were independently associated with an increased risk for mortality.
• In male KTRs, neither inadequate iodine intake (P = .47) nor lower levels of urinary iodine excretion (P = .36) were associated with the risk for mortality.
• Among female KTRs, only energy intake was significantly associated with urinary iodine excretion; however, among male KTRs, a higher intake of protein, meat, and bread showed positive associations with iodine excretion (P < .05 for all).

IN PRACTICE:

"[The study] findings underscore a sex-specific relationship between iodine status and survival after kidney transplantation, highlighting the potential clinical importance of monitoring and managing iodine nutrition, particularly in female KTR," the authors wrote.

SOURCE:

This study was led by Yvonne van der Veen, University Medical Center Groningen, Groningen, Netherlands. It was published online on March 30, 2026, in the Clinical Journal of the American Society of Nephrology.

LIMITATIONS:

The observational study design prevented the establishment of causality. Thyroid function was measured only at baseline, limiting the ability to assess temporal changes or to determine whether inadequate iodine intake was associated with progressive thyroid dysfunction over time. Additionally, the study population was predominantly White and from a single centre, and iodine intake was assessed at a single timepoint.

DISCLOSURES:

The TransplantLines Food and Nutrition Biobank and Cohort Study was funded by Top Institute Food and Nutrition and co-financed by the Dutch Ministry of Economic Affairs and Climate Policy. Some authors reported receiving research funding, serving as consultants or in speaking or advisory roles, or having employment or other ties with various pharmaceutical companies and organisations.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.