vitamin-d-2 and Infant--Premature--Diseases

Animal-experimental examinations show that the peroral or intramuscular application of a high dose of vitamin D2 or of D3 leads to a toxic effect of these compounds on the osteocytes and that the hypercalcaemia evoked by this is mainly to be traced back to an increased deliberation of calcium from the bones. After application of a larger dose of vitamin D the activation mechanism in the liver and in the kidneys is much inhibited for several weeks so that no formation of 1,25-hydroxy-vitamin-D takes place; consequently, no furthering effect on the mineralisation of the bones is performed. Therefore, it is recommended to use physiological doses in the prevention of rachitis (500-1,000 IU a day). During the pregnancy the activity of the enzymes which participate in the activation of the D-vitamins increases in the liver and the kidneys. The kidneys of the fetuses are able to form 1,25-hydroxy-vitamin-D. Vitamin D and 25-hydroxy-vitamin-D transgress through the placenta into the fetuses. Due to the adaptation mentioned and the increased formation of 1,25-hydroxy-vitamin-D the absorption of calcium and phosphate increases during pregnancy. Recent pathobiochemical knowledge concerning the metabolism of the D-vitamins in several diseases are described.

Topics: Bone and Bones; Calcium; Cholecalciferol; Ergocalciferols; Female; Glomerular Filtration Rate; Humans; Hypocalcemia; Infant, Newborn; Infant, Premature, Diseases; Intestinal Absorption; Liver; Osteogenesis; Osteoporosis; Parathyroid Hormone; Phosphates; Pregnancy; Rickets; Skin; Vitamin D

Topics: Calcitriol; Calcium; Drug Evaluation; Drug Therapy, Combination; Ergocalciferols; Humans; Infant; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases; Phosphorus; Rickets

Rickets was diagnosed in an extremely low-birthweight infant 16 weeks after birth. She had a normal plasma concentration of 25-hydroxyvitamin D, a relatively low level of 24,25-dihydroxyvitamin D, and a markedly elevated 1,25-dihydroxyvitamin D level compared with adult standards. The plasma concentrations of the vitamin D metabolites were, however, indistinguishable from those of healthy preterm infants who received a similar diet of human milk and vitamins. The results indicate that rickets was not caused by vitamin D deficiency or by abnormal vitamin D metabolism, but by calcium and/or phosphate deficiency, and that the calcium and phosphorous content of human milk may be inappropriately low for very low-birthweight infants.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Alkaline Phosphatase; Calcitriol; Calcium; Dihydroxycholecalciferols; Ergocalciferols; Female; Humans; Infant, Low Birth Weight; Infant, Newborn; Infant, Premature, Diseases; Milk, Human; Phosphorus; Rickets

Rickets, hypocalcemia, hypophosphatemia, and hyperparathyroidism were found in a low-birth-weight premature infant. The concentration of plasma calcitriol (1,25-dihydroxyvitamin D) was 145 pg/mL. With additional exogenous calcitriol (37.5 ng/kg/24 hr) given for eight weeks, the biochemical abnormalities were corrected and healing of rickets was evident. Three months later, while receiving only 400 IU of ergocalciferal daily, the patient had normal levels of serum calcium, phosphate, and alkaline phosphatase with a serum calcitriol concentration of 36 pg/mL. These observations suggest that rickets of prematurity may involve a malabsorption of calcium and phosphorus with an elevated calcitriol level needed to overcome this inadequate absorption. Additional doses of calcitriol may be of benefit in these infants, although it must be given carefully. Furthermore, the role of phosphate supplementation in these infants requires consideration.

Topics: Alkaline Phosphatase; Calcitriol; Calcium; Dihydroxycholecalciferols; Ergocalciferols; Female; Follow-Up Studies; Humans; Hydroxycholecalciferols; Infant, Newborn; Infant, Premature, Diseases; Parathyroid Hormone; Phosphates; Rickets

Topics: Animals; Calcium; Ergocalciferols; Fatty Acids; Female; Humans; Infant Food; Infant, Newborn; Infant, Premature, Diseases; Milk; Periosteum; Phosphates; Radiography; Rickets; Skull; Vitamin D

Topics: Ergocalciferols; Humans; Infant, Newborn; Infant, Premature, Diseases; Radiography; Rib Fractures; Rickets