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tumor-induced osteomalacia (oncogenic osteomalacia)
Etiology:
- secretion of FGF23 by small mesenchymal tumors*
* often difficult to localize
Clinical manifestations:
- fatigue, muscle weakness
- osteomalacia: severe bone pain, bone fractures
Laboratory:
- FGF23 in plasma elevated
- serum phosphate decreased, urine phosphate increased
- serum alkaline phosphatase is elevated
- 1,25-dihydroxyvitamin D in serum is low
- 25-hydroxyvitamin D in serum is generally normal
- serum PTH, serum calcium generally normal
Radiology:
- Dexa scan: reduced bone mineral density
Differential diagnosis:
- hypophosphatemic rickets: family history
- secondary hyperparathyroidism: hypocalcemia, serum 25-hydroxyvitamin D low
- Fanconi syndrome: FGF23 in plasma low
Management:
- surgical resection resolves symptoms
General
osteomalacia
paraneoplastic syndrome
References
- NEJM Knowledge+
- Florenzano P, Hartley IR, Jimenez M, Roszko K, Gafni RI, Collins MT.
Tumor-Induced Osteomalacia.
Calcif Tissue Int. 2021 Jan;108(1):128-142.
PMID: 32504138 Review.