title: Reversible primary hypothyroidism and elevated serum iodine level in patients with renal dysfunction.
abstract: Recovery of thyroid function in patients with both thyroid and renal dysfunction was studied. Among 245 patients with primary hypothyroidism (serum TSH greater than 10 mU/l), 36 had mild to severe renal dysfunction (serum urea nitrogen greater than 7.1 mmol/l and creatinine greater than 106 mumol/l). Of these 36 patients, recovery of the thyroid function after iodine restriction was observed in 30 (83%), in whom an elevated serum non-hormonal iodine level (median 236, range 67-15,591 micrograms/l, N = 19) and a high thyroidal radioactive iodine uptake (51.5 +/- 29.3% at 24 h, N = 26) were observed. The perchlorate discharge test was positive in 7 of 13 patients examined, suggesting an iodide organification defect rather than an atrophic or destructive change in the thyroid. Antithyroid antibodies were negative in 22 patients (73%) and an almost normal thyroid gland or colloid goitre was confirmed histologically in 8 of them. After a 13.2 mg potassium iodide loading test, 24 h urinary excretion of iodine was about 60% in normal controls, but only 10% in a different group of six euthyroid patients with renal dysfunction. These findings suggest that impaired renal handling of iodine rather than autoimmune mechanism may have a significant role in the pathogenesis of reversible hypothyroidism found in patients with renal dysfunction, probably through a prolonged Wolff-Chaikoff effect.
authors.affiliation: Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Okamura
authors.forename: M
authors.initials: M
authors.lastname: Yoshinari
authors.forename: T
authors.initials: T
authors.lastname: Kuroda
authors.forename: H
authors.initials: H
authors.lastname: Ikenoue
authors.forename: K
authors.initials: K
authors.lastname: Okazawa
authors.forename: T
authors.initials: T
authors.lastname: Mizokami
authors.forename: K
authors.initials: K
authors.lastname: Onoyama
authors.forename: M
authors.initials: M
authors.lastname: Fujishima
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D007455:Iodine / Q000097:blood* / Q000494:pharmacology; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D013961:Thyroid Gland / Q000473:pathology / Q000503:physiopathology
chemical_list: D007455:Iodine