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Epidemiology and etiology of osteomalacia

Marc K Drezner, MD
Section Editor
Peter J Snyder, MD
Deputy Editor
Jean E Mulder, MD


Osteomalacia is a disorder of decreased mineralization of newly formed osteoid at sites of bone turnover, whereas rickets is a disorder of defective mineralization of cartilage in the epiphyseal growth plates of children. Osteomalacia and rickets can occur together in children (open growth plates), but only osteomalacia occurs in adults (fused growth plates). Several different disorders cause osteomalacia via mechanisms that result in hypocalcemia, hypophosphatemia, or direct inhibition of the mineralization process.

This topic will review the epidemiology, pathogenesis, and different causes of osteomalacia. The clinical manifestations, diagnosis, and treatment of osteomalacia and the etiology and treatment of rickets are discussed separately. (See "Clinical manifestations, diagnosis, and treatment of osteomalacia" and "Etiology and treatment of calcipenic rickets in children".)


There is a growing prevalence of vitamin D deficiency in many countries, which when severe (25-hydroxyvitamin D <10 ng/mL [25 nmol/L]) and prolonged results in hypocalcemia, secondary hyperparathyroidism, secondary hypophosphatemia, and osteomalacia [1]. Nutritional vitamin D deficiency is therefore an increasingly common cause of osteomalacia in adults. Populations at risk include the homebound elderly who have little sun exposure and insufficient dietary calcium and vitamin D, patients with malabsorption related to gastrointestinal bypass surgery or celiac disease, and immigrants to cold climates from warm climates, especially women who wear traditional veils or dresses that prevent sun exposure [2,3]. Hereditary forms of vitamin D deficiency and resistance, which are identified in childhood, are associated with osteomalacia in adults, but these disorders are less common.

Osteomalacia can also occur in patients with primary hypophosphatemia due to one of the hereditary hypophosphatemic rickets syndromes (eg, X-linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets) or with tumor induced osteomalacia, an acquired paraneoplastic syndrome of renal phosphate wasting. The hereditary hypophosphatemic rickets syndromes present in childhood but persist in adulthood. These disorders are also uncommon. (See "Hereditary hypophosphatemic rickets and tumor-induced osteomalacia".)


Bone remodeling occurs continually on trabecular and Haversian bone surfaces. At any given time, about 7 percent of the bone surface is in the process of forming new bone. The osteoclast begins the cycle by excavating a cavity on the surface followed by refilling of the cavity by activated osteoblasts. New bone formation takes place in two steps:


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Literature review current through: Mar 2017. | This topic last updated: Sep 07, 2016.
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