Osteomalacia in practice of endocrinologist: etiology, pathogenesis, differential diagnosis with osteoporosis

Osteoporosis is the most common cause of low bone mineral density (BMD) and low-traumatic fractures in adults. However, differential diagnosis should also consider other causes of decreased BMD, including osteomalacia, as treatment for these conditions vary significantly. Osteomalacia is a systemic disorder characterized by decrease in bone strength due to of excessive accumulation of non-mineralized osteoid and uncoupling between bone matrix formation and mineralization. Osteomalacia in adults mostly develops due to severe vitamin D deficiency of any etiology, less often – along with kidney pathology, mesenchymal tumors secreting fibroblast growth factor 23 or hereditary metabolic bone diseases. Clinical symptoms of osteomalacia are nonspecific and mostly manifest by generalized diffuse bone pain, muscle weakness, skeletal deformities and often go unnoticed at initial stage of the disease. Histomorphometric examination is the most accurate method of the diagnosis, which allows assessment of bone formation rate and calcification. The utmost priority of the treatment of osteomalacia of any etiology is the elimination of vitamin D deficiency, hypocalcemia, hypophosphatemia and prevention of bone deformities progression and muscle hypotension.