CGA and essential hypertension: Plasma CgA in controls (49.0 ± 3.1 ng ml–1, mean ± SE) and in essential hypertensives (50.8 ± 3.5 ng ml–1) was lower (P< 0.0001) than in adrenocortical tumours (91.8 ± 13.2 ng ml–1), in phaeochromocytomas (254 ± 49 ng ml–1) and in patients with other neuroendocrine tumours (469 ± 84 ng ml–1).