Asymptomatic autoimmune thyroiditis and thyroid dysfunction in Alport's syndrome. A report of three families.

The purpose of this study was to investigate the significance of serum antithyroid antibodies in Alport's syndrome. Thyroid microsomal and thyroglobulin antibodies were assessed in three families with Alport's syndrome for a total of 11 patients and 17 healthy relatives, as well as in 40 haemodialysis patients and in 40 healthy subjects. Thyroid function tests, including the measurement of serum total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (fT4) and free triiodothyronine (fT3) concentrations, and thyrotropin-releasing hormone (TRH) stimulation tests were performed in all patients and subjects. Among patients with Alport's syndrome, five (45%) had elevated titres of thyroid microsomal antibodies and eight (73%) had positive titres of thyroglobulin antibodies, whereas only one healthy relative (6%) had circulating antithyroid antibodies. Fine-needle aspiration biopsy of the thyroid demonstrated a lymphocytic infiltration that indicated the existence of asymptomatic autoimmune thyroiditis in all five patients with elevated thyroid microsomal antibody titres. The prevalence of antithyroid antibodies in healthy subjects and in haemodialysis patients was 7.5% and 12.5% respectively. Functional tests demonstrated a thyroid dysfunction in four of five patients with asymptomatic autoimmune thyroiditis. Two patients had evidence of subclinical hypothyroidism. Two other patients, both with end-stage renal failure, showed a blunted TSH response to TRH, increased fT4 and elevated borderline fT3. The present study indicates that elevated titres of serum antithyroid antibodies may be detected in patients with Alport's syndrome. These patients are at risk of developing asymptomatic autoimmune thyroiditis and thyroid dysfunction. Subclinical hypothyroidism and, perhaps, preclinical hyperthyroidism may be found in these patients.