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- Title
Increased serum levels of a parathyroid hormone-like protein in malignancy-associated hypercalcemia.
- Authors
Budayr, Amer A.; Nissenson, Robert A.; Klein, Robert F.; Pun, K.K.; Clark, Orlo H.; Diep, Dinh; Arnaud, Claude D.; Strewler, Gordon J.; Budayr, A A; Nissenson, R A; Klein, R F; Clark, O H; Diep, D; Arnaud, C D; Strewler, G J
- Abstract
<bold>Study Objective: </bold>To measure the serum levels of a newly described parathyroid hormone-like protein (PLP) which was isolated from malignant tumors associated with hypercalcemia, and determine whether PLP is a humoral factor in malignancy-associated hypercalcemia.<bold>Design: </bold>A cross-sectional study of serum levels of PLP using a newly developed radioimmunoassay.<bold>Setting: </bold>A university-affiliated Veterans Administration hospital in San Francisco, California, a University hospital in Hong Kong, and a private hospital in Danville, Pennsylvania.<bold>Patients: </bold>Patients with hypercalcemia (calcium greater than 2.65 mmol/L) and a diagnosis of malignancy were studied. Control groups included normocalcemic patients with malignancy, patients with hyperparathyroidism, and normal subjects.<bold>Measurements and Main Results: </bold>Serum immunoreactive PLP (iPLP) levels in normal subjects were less than 2.5 pmol eq/L (10 pg/mL), and 68% of subjects had undetectable levels. The serum concentration of iPLP was normal in 15 of 16 hypercalcemic patients with hyperparathyroidism. Serum iPLP was increased (greater than 2.5 pmol eq/L) in 36 of 65 (55%) patients with malignancy-associated hypercalcemia, with a mean value of 6.1 +/- 0.9 pmol eq/L (24 pg/mL). In a subgroup of patients with solid tumors serum iPLP was increased in 30 (71%) of 42 hypercalcemic patients, with a mean value of 6.5 +/- 0.9 pmol eq/L. Serum iPLP was elevated in only 3 of 23 normocalcemic patients with cancer. In patients with solid malignancies (n = 59), levels of iPLP were positively correlated with the total serum calcium (r = 0.43, P less than 0.01).<bold>Conclusion: </bold>The data indicate a relation between the serum concentration of iPLP and the presence of hypercalcemia in solid malignancies. The results support a role for PLP as a humoral mediator of hypercalcemia in most patients with solid tumors. Measurement of iPLP should be useful in the differential diagnosis of hypercalcemia.
- Subjects
SERUM; PARATHYROID hormone-related protein; CANCER; HYPERCALCEMIA; RODENTS
- Publication
Annals of Internal Medicine, 1989, Vol 111, Issue 10, p807
- ISSN
0003-4819
- Publication type
journal article
- DOI
10.7326/0003-4819-111-10-807