The thyroid in ulcerative colitis and Crohn's disease. I. Thyroid radioiodide uptake and urinary iodine excretion.

In order to investigate the prevalence of iodine depletion in chronic inflammatory bowel disease two separate studies have been performed. One was devoted to the 24-hour urinary iodine excretion and 50 patients with ulcerative colitis or Crohn's disease were examined and compared with 102 controls. In the other study the thyroid 131I uptake was compared in 38 patients and 36 controls. Ten of the 50 patients with chronic inflammatory bowel disease had a 24-hour urinary iodine excretion less than 40 mug, compared with 5 of the 102 controls (p greater than 0.01). Sixteen of the 38 patients had a 24-hour thyroid 131I uptake of 50% or more of the administered test does, compared with 4 of the 36 controls (p smaller than 0.01). These results are compatible with an increased occurrence of iodine deficiency in patients with chronic inflammatory bowel disease. Treatment with corticosteroids or Salazopyrin or a milk-free diet did not influence these findings. No evidence was found of an impaired absorption of inorganic iodide from the gut.?31