Molybdenum balance studies in premature male infants

Despite the fact that the trace element molybdenum (Mo) is essential, there is insufficient knowledge about the demands in infancy. Mo balances were therefore assessed under consideration of formula Mo concentrations ranging from 0.125 to 2.704 μmol/l. Sixteen premature male infants participated in the investigation. Their birth weights were between 1500 and 1990 g, the median (range) gestational age was 34 (32–36) weeks and the post-conceptual age at the time of study 37.4 (34.1–40.6) weeks. Twenty-four balance studies were performed and the materials analysed by atomic absorption spectroscopy. Infants with a “low” Mo intake received 0.024 (0.020–0.035) μmol/kg per day, had a urinary excretion of 0.02 (0.008–0.045) and a retention of 0.0006 (−0.03 to 0.008) μmol/kg per day. Infants with a “high” intake received 0.284 (0.227–0.487) μmol/kg per day, had a urinary excretion of 0.243 (0.118–0.378) and a retention of 0.022 (−71.1 to 141.44) μmol/kg per day. Since the median urinary excretion exceeded 60% of the Mo intake at low and high intakes, sufficient resorption but minimal retention was assessed at low intakes of Mo. Conclusion In view of the limited knowledge of long-term exposure to an elevated molybdenum intake and the substantial retention observed at higher intakes, upper limits should be set for molybdenum concentrations in preterm infant formulas. Received: 22 February 2000 and in revised form 13 July 2000 and 23 August 2000 Accepted: 25 August 2000