Iodine Absorption in Celiac Children: A Longitudinal Pilot Study

Abstract

Background: non-autoimmune thyroid disorder is a common finding in celiac patients, more frequent than in the general population. An impairment of iodine absorption has been hypothesized, but it has never been investigated so far. We aimed to evaluate the iodine absorption in children and adolescents with newly diagnosed celiac disease. Methods: 36 consecutive celiac patients (age 7.4 years, range 2.4-14.5 years) before starting a gluten-free diet (GFD) were enrolled. We assayed the urinary iodine concentration (UIC) in a 24-h urine sample, at baseline (T0) after 3 (T1) and 12 months (T2) of GFD. Results: UIC at T0 was 64 μg/L (IQR 45-93.25 μg/L) with an iodine deficiency rate of 77.8%. UIC was not different according to histological damage, clinical presentation (typical vs atypical); we found no correlation with the thyroid function tests and auxological parameters. UIC was not statistically different at T1 (76 μg/L) and T2 (89 μg/L) vs T0. UIC at T2 was similar between patients with positive and negative anti-transglutaminase antibodies at T2. No patients presented overt hypothyroidism during the study. Conclusions: We found that iodine absorption in celiac children is impaired compared to the general population; it increases slightly, but not significantly, during the GFD. We should regularly reinforce the need for a proper iodine intake in celiac disease patients to reduce iodine deficiency risk.

Keywords: celiac disease; endocrine consequences; iodine; thyroid; urinary iodine concentration.

Figure 1

24-h urinary iodine concentration (UIC) boxplot and scatter plot in patients with B1 [72 (45/88) μg/L] and B2 [63 (44.5–105) μg/L]) grading at T0 (p = ns).

Figure 2

24-h urinary iodine concentration (UIC) boxplot and scatter plot in patients with positive (10 patients) and negative (13 patients) celiac serological tests at T2. p-value was not significant in both groups. In patients with negative serological celiac tests UIC was 60 μg/L (44/103.5 μg/L) at T0, 82.5 μg/L (65.5/113.3 μg/L) at T1, and 84.5 μg/L (51/120.3 μg/L) at T2. In patients with positive serological celiac tests UIC was 77 μg/L (46.5/107.5 μg/L) at T0, 78 μg/L (50/121.5 μg/L) at T1, and 89 μg/L (32/136.5 μg/L) at T2.