Measurement of sialyl transferase activity and serum glycoproteins in malignant and beningn (hyperparathyroid) hypercalcemia.

Serum sialyl tranferase activity (STA) and protein bound carbohydrate were measured in hypercalcemic patients with surgically documented hyperparathyroidism (n = 15) or with cancer without skeletal metastases (n = 10). Precipitable protein-bound sialic acid and hexosamine, but not neutral hexoses or fucose were significantly (P less than 0.025) increased 40% and 21% respectively, in the perchlorate treated sera of cancer patients. Measurements of some specific serum glycoproteins by radial immunodiffusion assay were also different (P less than 0.05). Mean seromucoid protein was almost twice as great in the group with cancer (P less than 0.005), but four of these values overlapped those from the patients with hyperparathyroidism. The mean STA was 21.1 (range, 9.0-46.8) activity units in the patients with the cancer and 9.2 (range 1.0-17.8) in the patients with hyperparathyroidism (P less than 0.005). Six of the patients with cancer had values above the upper limit of the group with hyperparathyroidism. A discriminant function generated from these data correctly classified all the patients with hyperparathyroidism and 70% of those with cancer. Measurements of seromucoid and STA deserve further consideration as a way to discriminate some cases of hypercalcemia.