Studies on chromogranin levels in human blood.

Considering that the determination of chromogranin levels in the blood for the diagnosis of pheochromocytoma will provide clinically useful information, an attempt was made to establish the serological assay system for blood chromogranin, and also chromogranin levels in the blood of normal subjects, patients with essential hypertension and a patient with pheochromocytoma were studied. Chromogranin was isolated and purified from the granular internal fluid of the catecholamine storing vesicles of the pig adrenal glands. The antibodies against chromogranin and the chromogranin-sensitized sheep red blood cells were prepared; and chromogranin levels in the blood were determined by the passive hemagglutination inhibition reaction (PHI), using the microtiter system. As it was observed in the determination of chromogranin levels in the blood by PHI that globulin fractions gave rise to nonspecific agglutination by this reaction system, the serum samples were pretreated by the salting-out method with ammonium sulfate into the albumin fraction, on which PHI was performed. Chromogranin levels in the blood of 41normal subjects and 12 patients with essential hypertension in terms of inhibition values of PHI were distributed chiefly in the range from1: 20 to 1: 80. The level in the blood of one patient with pheochromocytoma was 1: 640, whose titer was obviously higher than the titers in the blood of normal subjects and patients with essential hypertension. These evidences suggest that the determination of chromogranin levels in the blood will provide useful information for the diagnosis of pheochromocytoma.