Congenital nephrotic syndrome and persistent hypothyroidism after bilateral nephrectomy

Congenital nephrotic syndrome is commonly associated with hypothyroidism. Thyroid hormone supplementation is recommended as standard of care. The hypothyroidism is postulated to occur secondary to chronic massive proteinuria with loss of thyroid binding globulin, thyroid hormone and iodine. Previous reports have indicated that thyroxin may be discontinued following bilateral nephrectomy. We report our experience with one child with congenital nephrotic syndrome, Finnish type, and hypothyroidism who had a high requirement for thyroxin (100-150 microg/d) from infancy to 4 years of age. Hypothyroidism persisted despite bilateral nephrectomy and later following renal transplantation. However, his thyroxin requirement is now substantially lower (62.5 microg/d) at age 14 years. No goiter was detected clinically and antithyroid antibodies were negative. Thyroid ultrasound and 123I scan revealed a thyroid gland in the anatomically normal location. 123I uptake was elevated, 18% at 6 hours and 51% at 24 hours (normal values: 3-16% at 6 hours and 8-25% at 24 hours). Perchlorate was unavailable for a perchlorate washout study. We speculate that this patient may have an intrinsic problem with thyroid hormone synthesis. It is unclear whether this is related or coincidental to the Finnish nephrotic syndrome. We recommend following thyroid functions closely if thyroxin is discontinued following bilateral nephrectomies in Finnish type congenital nephrotic syndrome.