Human chorionic gonadotropin subunit measurement in primary hyperparathyroidism

The concentration of subunits of hCG (hCGα and hCGβ) was determined in plasma or serum from 70 patients with primary hyperparathyroidism (1°HPT). Two of three patients with parathyroid carcinoma showed elevation in plasma concentrations of both subunits, which fell after surgical removal of the tumor. An extract prepared from the tumor of 1 of these patients contained the subunits in high concentrations, whereas in extracts similarly prepared from tissues removed from 7 patients with benign 1°HPT, the subunits were not detectable or were present in much lower concentrations. In 42 cases of benign 1° HPT, samples from veins containing a 10-fold gradient of parathyroid hormone obtained during selective venous catheterization and peripheral samples from the same patients were analyzed for hCG subunits. Only 1 patient demonstrated a mild elevation of hCGα in parathyroid venous effluent alone that may have represented subunit release by apparently benign parathyroid tissue. Thirty patients with multiple endocrine neoplasia type I were tested; 8 evidenced clinically active islet cell tumors, and 6 of these 8 showed high circulating concentrations of hCGα (and hCGβ in 1 case). Patients in the multiple endocrine neoplasia type I group with 1°HPT or pituitary tumors, but no evident pancreatic islet disease, did not show elevations in subunit concentrations. Thus, in patients with 1°HPT, determination of subunits of hCG may be helpful in making the diagnosis of parathyroid carcinoma or in screening for associated (and probably malignant) pancreatic islet disease.