Kalzium- und Vitamin-D-Substitution bei Osteoporose

Insufficient calcium intake results in increased bone resorption leading to osteoporosis. In this situation a normal serum calcium level is maintained at the cost of the skeleton, i.e. development of secondary hyperparathyroidism. Vitamin D enhances intestinal calcium absorption and osteoid mineralization and reduces parathyroid hormone secretion. Therefore, calcium and vitamin D supplements are generally recommended for prevention and as a basic therapy of osteoporosis. When dosing these supplements nutritional calcium and vitamin D synthesis during sun exposure have to be taken into consideration. It is also important to take into consideration that calcium intake and intestinal absorption as well as vitamin D production decrease with increasing age. Calcium intake should be in the range of 1000–1500 mg and vitamin D 800–2000 IU per day or 25-hydroxy-vitamin D plasma levels between 30 and 50 ng/ml. With these dosages hypercalcemia and hypercalciuria are extremely rare adverse events and the risk of kidney stones is very low. Communications of increased cardiovascular events related to long-term calcium or calcium and vitamin D intake induced a significant reduction of prescriptions of corresponding preparations. Other publications, however, communicated cardioprotective effects of vitamin D and recent publications could not confirm an increased risk of cardiovascular events with calcium alone or in combination with vitamin D and even demonstrated reduced mortality. Until final clarification of these discrepant study results a regular moderate intake of calcium and vitamin D supplements within the abovementioned dosage range is recommended.