Fibroblast growth factor 23 concentrations in humoral hypercalcemia of malignancy and hyperparathyroidism.
OBJECTIVE
To determine whether fibroblast growth factor 23 (FGF 23) concentrations are increased in the serum of patients with humoral hypercalcemia of malignancy and in those with hyperparathyroidism.


METHODS
Serum samples from patients with hypercalcemia and documented elevations of parathyroid hormone-related protein or parathyroid hormone levels were examined for FGF 23 concentrations. Specimens from healthy age-matched controls were evaluated to establish a reference range for FGF 23.


RESULTS
Mean +/- SEM concentrations of FGF 23 were elevated in the 7 patients with humoral hypercalcemia of malignancy (385 +/- 134 relative unit [RU]/mL) compared with 11 healthy controls (43.9 +/- 5.8 RU/mL; P = .005). In the 11 patients with hyperparathyroidism, FGF 23 concentrations were increased (mean +/- SEM 86.6 +/- 228 RU/mL), but the increases were not statistically significant. The increases in FGF 23 in these disorders did not correlate with changes in serum phosphate or 1alpha,25-dihydroxyvitamin D levels.


CONCLUSIONS
Levels of FGF 23 are elevated in patients with tumors associated with humoral hypercalcemia of malignancy. The precise cause of such elevations requires further investigation.
Singh
Ravinder J
RJ
Division of Clinical Biochemistry and Immunology, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minn 55905, USA.
Kumar
Rajiv
R
D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D006934:Hypercalcemia / Q000378:metabolism*; D006961:Hyperparathyroidism / Q000097:blood*; D009369:Neoplasms / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood*
C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23