Mineral requirements of low-birth-weight infants.

Abstract

The minerals calcium (Ca), magnesium (Mg), and phosphorus (P) are essential for tissue structure and function. Recent studies have resulted in a more rational approach to the management of mineral intake in preterm infants receiving parenteral nutrition (PN) and enteral nutrition (EN). For preterm infants requiring PN, the use of PN solutions with a Ca content of 1.25-1.5 mmol/dl (50-60 mg/dl), a P content of 1.29-1.45 mmol/dl (40-45 mg/dl), and an Mg content of 0.2-0.3 mmol/dl (5-7 mg/dl) is supported by studies of mineral homeostasis with serial chemical and calciotropic hormone measurements, standard balance studies, and improved radiographic indices of bone mineralization. For infants requiring EN, an intake of approximately 4 mmol (200 mg) of Ca, 3.2 mmol (100 mg) of P, and 0.33 mmol (8 mg) of Mg/kg/day based on an average retention rate of 64% for Ca, 71% for P, and 50% for Mg should be sufficient to meet the requirements of preterm infants in early infancy. This level of intake is supported by data from balance studies using standard and stable isotope techniques, changes in bone mineral content (BMC) measurements, and calciotropic hormone data. Based on the timing of development of fractures and rickets, changes in BMC, and skeletal growth data, the increased Ca and P intake should continue for at least 3 months after birth or until reaching a body weight of about 3.5 kg. In addition, nonnutritional factors may have the potential to increase mineral loss and disturb mineral homeostasis; chronic diuretic therapy increases mineral loss, and aluminum contamination of nutrients theoretically may compound any skeletal disorder. Thus, attention to the level of mineral intake and factors important in mineral loss and mineral metabolism should optimize mineral retention in small preterm infants.

Review: Parenteral Nutrition‐Related Bone Disease

“…These To minimize the risk of precipitation from increased concentrations of Ca and P in situations where the infant is being fluid restricted, recommendations for Ca and P intake are based on concentration of milligrams per deciliter of PN solution rather than in the amount of milligrams per kilogram in the patient. 28,29 There are no documented major complications associated with the currently recommended higher Ca and P intake for infants receiving PN. Serial abdominal ultrasound examinations showed that biliary sludge did not occur with greater frequency in infants receiving the higher Ca, P solution compared with those with lower mineral intake.…”

“…5,6,[25][26][27][28] Early studies of infants with nutritionrelated bone disease frequently report the presence of hypophosphatemia, elevated serum alkaline phosphatase activity, decreased urinary P, and increased urinary Ca loss. These findings are consistent with the presence of mineral deficiency, particularly P deficiency.…”

Calcium, phosphorus and magnesium needs for the low‐birth‐weighi infant

“…Koo et a1 (9) first demonstrated the need for higher doses of Ca and P in a study of parenteral mixtures administered to LBW infants (1.1 kg birth weight, 29 weeks' gestation) for 5-52 days due to a variety of medical and surgical conditions. Parenteral Ca and P at 15 mM each, compared with 5 mM concentrations, when administered at approximately 125 ml/kg/day, resulted in normalized serum P and 1,25-dihydroxyvitamin D concentrations, lower urinary Ca/creatinine ratios and % TRP that remained <90%.…”

“…Although published guidelines suggest that the Ca and P composition of parenteral nutrition mixtures should be 12.5-15 and 12.9-14.5mM, respectively, recent studies indicate that concentrations of Ca and P, 20 mM each, are achievable and potentially beneficial for bone mineralization (8, 9,13). These newer approaches are practical only under conditions in which the constituents of the parenteral nutrition solutions are controlled to allow solubility of Ca and P. For example, the total quantity of amino acids (>2.2 g%, as TrophAmine, Kendall-McGaw Laboratories, Irvine, CA, USA and Aminosyn-PF, Abbott Laboratories, Chicago, IL, USA) with the addition of cysteine hydrochloride (added as 30-40 mg/g amino acids) promote greater solubility of Ca and P, principally because of a lowered pH (8, 9,15). Storage time and temperature, type and concentration of mineral salts, and the order in which the salts are mixed, are important factors that affect the solubility of parenteral Ca and P (12,(15)(16)(17).…”

Parenteral Nutrition in Neonatus and Compatibility Issues: a Review Article

“…Amounts of calcium and phosphorus are initiated at maintenance levels and advanced when energy and protein intakes are adequate to support intrauterine accretion rates of lean tissue [29]. The adequacy of these nutrients from PN solutions has been studied extensively in the premature population and in-depth discussions appear elsewhere [30,31,[68][69][70][71][72].…”