[Calcium-phosphate metabolism in pre-term infants].

Physiological and clinical aspects are discussed in this review on calcium-phosphate metabolism in pre-term infants. Calcium accumulation in the bone mass of the foetus is related to the gestational age, and mainly occurs during the last weeks of gestation. Therefore, after birth, hypocalcemia is more frequent in pre-term than term infants. However, clinical symptoms of hypocalcemia, e.g. attacks of apnea, hyperexcitability and hypotonia, are rarely observed. Such symptoms depend upon the serum concentration of ionized calcium and this concentration is influenced by various metabolic factors. During the first two weeks of life phosphate is elevated in comparison to later periods. In spite of sufficient vitamin D supplementation low serum phosphate levels occur due to insufficient supply of phosphate. This correlates with evidence of rickets. An increased alkaline phosphatase activity can be considered an early and sensitive indicator. Pre-term infants develop rickets more frequently than term infants due to calcium-phosphate deficiency. Vitamin D supplementation alone is insufficient and should be combined with phosphate, as had been stated previously.