Hypothyroidism in primary hyperoxaluria type 1.

We describe 4 patients, aged 3 months to 23 years, with end-stage renal disease and severe, symptomatic hypothyroidism. All 4 had primary hyperoxaluria type 1 (PH1) with diffuse tissue (kidneys, skeleton, eyes, heart) calcium-oxalate deposition, a condition known as oxalosis. The hypothyroidism responded to thyroid hormone replacement therapy. Clinical hypothyroidism within the framework of PH1/oxalosis was probably caused by thyroid tissue damage from an abundance of calcium oxalate. We recommend that thyroid function be monitored in patients with PH1 and oxalosis.