Moderate renal failure in association with prolonged acquired hypothyroidism in children.

We evaluated five children with prolonged primary hypothyroidism and noted a significant reduction in renal function (40%), which was reversible with hormonal replacement. This decline was higher than reported in adults and was of sufficient magnitude to warrant altering drug-dosing schedules. Furthermore, patients with moderately reduced renal function should be carefully evaluated for signs and symptoms of hypothyroidism.