Confirmation of serum salicylate levels in Reye's syndrome: a comparison between the Natelson colorimetric method and high performance liquid chromatography.

Serum was obtained from 11 patients with Reye's syndrome at admission and analyzed for the presence of salicylates by the Natelson colorimetric technique and high performance liquid chromatography. Salicylate levels obtained by the Natelson method had a mean of 6.00 mg/dl +/- 4.58; the mean HPLC salicylic acid level was 5.09 mg/dl +/- 5.14. The correlation coefficient was 0.985 with a linear regression line y = 0.8788x + 1.527. No other salicylate metabolites nor interfering substances were identified. Once the accuracy of the Natelson method was confirmed, the charts of 82 patients were reviewed for admission salicylate levels. The overall mean was 8.63 mg/dl (survivors, 8.45 mg/dl +/- 8.56; fatalities, 9.28 mg/dl +/- 5.34). There was no correlation found between admission salicylate level and peak ammonia level, another important index of disease severity.