Osteoporosis, Osteomalacia and Vitamin D

The hormone vitamin D regulates calcium and bone metabolisms. Vitamin D has an indirect action on bone tissue by regulating phosphocalcium metabolism, the main organs being the kidney and intestine. Chronic diseases of these organs can lead to vitamin D deficiency. Vitamin D deficiency is almost worldwide epidemic and is revealed when the levels of circulating 25-hydroxy-vitamin D [25(OH)D] are less than 20 ng/ mL (50 nmol/L), which chronically can lead to osteoporosis and/or osteomalacia. Data from studies between the relationships of bone mineral density at the lumbar spine, at the proximal femur and at the 1/3 distal radius with the 25(OH)D blood levels are controversial. Prolonged vitamin D deficiency increases the risk of fracture through its effects on the bone metabolism and the risk of falling, once it can cause osteomalacia and muscle weakness, leading to falls and fragility/osteoporotic fractures. In patients on anti-resorptive medication for osteoporosis it is necessary to ensure vitamin D and calcium supplementation. In osteomalacia, the symptoms are generally unspecific and in chronic osteomalacia deformations of skeletal segments may be detected, as well as an increased number of falls, and even convulsions and/or tetany. Treatment of osteomalacia should correct the biochemical abnormalities and maintain the blood 25(OH)D levels >= 30 ng/mL and the PTH blood concentrations within the reference ranges for normality.