Determination of enolase isozymes in various adrenal gland tumours

Enolase isozymes (alpha enolase and gamma enolase) in the extracts of adrenal tumours (phaeochromocytoma, adenoma of primary aldosteronism and Cushing's syndrome, and neurinoma) were determined by means of enzyme immunoassay systems. The mean +/- SEM, respectively, of alpha and gamma enolase levels were 2.5 +/- 0.37 microgram/mg protein and 3.2 +/- 0.69 micrograms/mg protein for 9 phaeochromocytomas, 15.2 +/- 3.1 microgram/mg protein and 0.65 +/- 0.18 microgram/mg protein for three adenomas with primary aldosteronism, 10.8 +/- 3.0 micrograms/mg protein and 0.23 +/- 0.02 micrograms/mg protein for five adenomas causing Cushing's syndrome, and 3.8 +/- 0.88 micrograms/mg protein and 0.30 +/- 0.15 micrograms/mg protein for three neurinomas. Thus, the gamma enolase concentration in the extract of phaeochromocytoma was higher than that of other adrenal tumours. The serum level of gamma enolase was determined in 36 patients with adrenal tumours and 26 normal controls by radioimmunoassay. The mean +/- SEM for gamma enolase level was 5.4 +/- 0.3 ng/ml in normal controls, 9.1 +/- 0.9 ng/ml for 10 patients with phaeochromocytoma, 6.3 +/- 0.3 ng/ml for 11 with primary aldosteronism, 5.5 +/- 0.4 ng/ml for 11 with Cushing's syndrome, and 5.1 +/- 0.7 ng/ml for four with neurinoma. Thus, patients with phaeochromocytoma had a significantly higher serum gamma enolase levels than did those with tumours derived from adrenal cortex and normal controls. In patients with phaeochromocytoma, serum gamma enolase levels showed a significant positive correlation with urinary adrenaline levels (P less than 0.05), and after resection the elevated level of gamma enolase fell significantly (P less than 0.05) and returned to normal.(ABSTRACT TRUNCATED AT 250 WORDS)