Reversible renal impairment caused by thyroid disease.

Renal impairment is a common finding in clinical practice and is increasingly recognized with the routine reporting of estimated glomerular filtration rates. Clinical assessment is essential to determine which of the many possible investigations are appropriate. Thyroid hormones regulate many cellular functions, and abnormalities of the active thyroid hormones, thyroxine (T(4)) and tri-iodothyronine (T(3)), can influence serum creatinine levels. Evaluation of thyroid function is easily overlooked, but important in this context, as hypothyroidism is common and can cause renal impairment, which is typically reversible. Renal dysfunction may also be more frequent in hyperthyroidism than is recognized. This report describe how a dramatic elevation in serum creatinine paralleled the development of hyperthyroidism, with a return of the creatinine to normal following treatment of the hyperthyroid state.