Kazuyuki Yamauchi

EFFECT OF FUSARIC ACID (A DOPAMINE β‐HYDROXYLASE INHIBITOR) ON PHAEOCHROMOCYTOMA

Fusaric acid, an inhibitor of dopamine β‐hydroxylase, which converts dopamine to noradrenaline, lowered the blood pressure and induced a subjective improvement in patients with phaeochromocytoma. These effects may be due either to an impairment of catecholamine biosynthesis or to a direct action on the blood vessels. The use of this drug in the treatment of patients with inoperable malignant phaeochromocytoma or neuroblastoma may improve symptoms and prolong survival.

Determination of enolase isozymes in various adrenal gland tumours

Enolase isozymes (α enolase and γ enolase) in the extracts of adrenal tumours (phaeochromocytoma, adenoma of primary aldosteronism and Cushings syndrome, and neurinoma) were determined by means of enzyme immunoassay systems. The mean ± SEM, respectively, of α and γ enolase levels were 2.5 ± 0.37 μg/mg protein and 3‐2 ± 0–69 μg/mg protein for 9 phaeochromocytomas, 15.2 + 3.1 μg/mg protein and 0.65 ± 0.18 μg/mg protein for three adenomas with primary aldosteronism, 10.8 ± 3.0 μg/mg protein and 0.23 ± 0.02 μg/mg protein for five adenomas causing Cushings syndrome, and 3.8 ± 0.88 μg/mg protein and 0.30 ± 0.15 μg/mg protein for three neurinomas. Thus, the γ enolase concentration in the extract of phaeochromocytoma was higher than that of other adrenal tumours. The serum level of γ enolase was determined in 36 patients with adrenal tumours and 26 normal controls by radioimmunoassay. The mean + SEM of γ enolase level was 5.4 ± 0.3 ng/ml in normal controls, 91 ± 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 Cushings syndrome, and 5.1 ± 0.7 ng/ml for four with neurinoma. Thus, patients with phaeochromocytoma had a significantly higher serum γ enolase levels than did those with tumours derived from adrenal cortex and normal controls. In patients with phaeochromocytoma, serum γ enolase levels showed a significant positive correlation with urinary adrenaline levels (P<0.05), and after resection the elevated level of γ enolase fell significantly (P<0.05) and returned to normal. These results indicate that γ enolase in serum may be a useful marker for the differential diagnosis of adrenal tumours and therapeutic monitoring of phaeochromocytoma.