Hypouricaemia and inappropriate secretion of antidiuretic hormone in small cell bronchogenic carcinoma.

Hypouricaemia has been observed in patients with the syndrome of inappropriate secretion of antidiuretic hormone (IADH). Accordingly, 69 patients with untreated bronchogenic small cell carcinoma were examined for IADH. Serum urate was also measured. IADH was proven in 25 (35%) of the 69 patients. The median serum concentration of urate in these patients was 0.26 mmol/l (range 0.13-0.50), compared to 0.36 mmol/l (0.21-0.60) in the 44 patients without IADH. The difference is statistically significant (p less than 0.01), but serum urate--when used alone--is lacking in both sensitivity and specificity for the diagnosis of IADH.