Autoimmune thyroiditis in association with membranous nephropathy.

Hashimoto's thyroiditis and membranous nephropathy are believed to be mediated by immune mechanisms. A 12 year-old patient is reported who presented with fatigue, dislike of cold, pallor and growth retardation. Initial laboratory assessment showed moderate proteinuria and impaired renal function (serum creatinine 2.3 mg/dl), and hypothyroidism due to autoimmune thyroiditis. Light, immunofluorescence and electron microscopy of the renal biopsy showed membranous nephropathy. The patient recovered from nephropathy after substitution of thyroid hormone and therapy with prednisone. Megalin can be envisaged as a potential pathogenetic link between the two disease entities. The glycoprotein megalin is expressed on thyroid cells in a TSH-dependent manner and may have a crucial role in the immunopathogenesis of glomerular injury in membranous nephropathy. For similar cases, we want to encourage colleagues to consider this hypothesis and to examine blood and renal biopsy specimens for the presence of megalin and antibodies against it.