- Osteomalacia is characterized by defective mineralization of osteoid. Bone biopsy reveals increased thickness of osteoid seams and decreased mineralization rate, assessed by tetracycline labeling.
- Suboptimal vitamin D nutrition, indicated by plasma 25-hydroxy vitamin D (25[OH]D) levels <30 ng/mL, is very common and contributes to the development of osteoporosis.
- Dietary vitamin D deficiency
- Malabsorption of vitamin D and calcium because of intestinal, hepatic, or biliary disease
- Disorders of vitamin D metabolism (e.g., renal disease, vitamin D–dependent rickets)
- Vitamin D resistance
- Chronic hypophosphatemia
- Renal tubular acidosis
- Clinical findings include diffuse skeletal pain, proximal muscle weakness, waddling gait, and propensity to fractures.
- Osteomalacia should be suspected in a patient with osteopenia, elevated serum alkaline phosphatase, and either hypophosphatemia or hypocalcemia.
- Serum alkaline phosphatase is elevated. Serum phosphorus, calcium, or both may be low.
- Serum 25(OH)D levels may be low, establishing the diagnosis of vitamin D deficiency or malabsorption.
- Radiographic findings include osteopenia and radiolucent bands perpendicular to bone surfaces (pseudofractures or Looser zones). Bone density is decreased.
- Dietary vitamin D deficiency can initially be treated with ergocalciferol 50,000 international units (IU) PO weekly for 8 weeks to replete body stores, followed by long-term therapy with cholecalciferol 2000 IU/d.
- Malabsorption of vitamin D may require continued therapy with high doses such as 50,000 IU PO per week. The dose should be adjusted to maintain serum 25(OH)D levels above 30 ng/mL. Calcium supplements, 1 g PO daily, tid, may also be required. Serum 25(OH)D and serum calcium should be monitored every 6–12 months to avoid hypercalcemia.
- Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2011;96:1911-1930. [PMID:21646368]
- Munns CF, Shaw N, Kiely M, et al. Global consensus recommendations on prevention and management of nutritional rickets. J Clin Endocrinol Metab. 2016;101:394-415. [PMID:26745253]
- Chapter 24: Endocrine
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Bhat, Pavat, et al., editors. "Osteomalacia." Washington Manual of Medical Therapeutics, 35th ed., Wolters Kluwer Health, 2016. The Washington Manual, www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602906/all/Osteomalacia.
Osteomalacia. In: Bhat PP, Dretler AA, Gdowski MM, et al, eds. Washington Manual of Medical Therapeutics. Wolters Kluwer Health; 2016. https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602906/all/Osteomalacia. Accessed March 28, 2023.
Osteomalacia. (2016). In Bhat, P., Dretler, A., Gdowski, M., Ramgopal, R., & Williams, D. (Eds.), Washington Manual of Medical Therapeutics (35th ed.). Wolters Kluwer Health. https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602906/all/Osteomalacia
Osteomalacia [Internet]. In: Bhat PP, Dretler AA, Gdowski MM, Ramgopal RR, Williams DD, editors. Washington Manual of Medical Therapeutics. Wolters Kluwer Health; 2016. [cited 2023 March 28]. Available from: https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602906/all/Osteomalacia.
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TY - ELEC T1 - Osteomalacia ID - 602906 ED - Williams,Dominique, ED - Bhat,Pavat, ED - Dretler,Alexandra, ED - Gdowski,Mark, ED - Ramgopal,Rajeev, BT - Washington Manual of Medical Therapeutics UR - https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602906/all/Osteomalacia PB - Wolters Kluwer Health ET - 35 DB - The Washington Manual DP - Unbound Medicine ER -