Initial Amino Acid Intake Influences Phosphorus and Calcium Homeostasis in Preterm Infants – It Is Time to Change the Composition of the Early Parenteral Nutrition

Abstract

BackgroundEarly aggressive parenteral nutrition (PN), consisting of caloric and nitrogen intake soon after birth, is currently proposed for the premature baby. Some electrolyte disturbances, such as hypophosphatemia and hypercalcemia, considered unusual in early life, were recently described while using this PN approach. We hypothesize that, due to its impact on cell metabolism, the initial amino acid (AA) amount may specifically influence the metabolism of phosphorus, and consequently of calcium. We aim to evaluate the influence of AA intake on calcium-phosphorus metabolism, and to create a calculation tool to estimate phosphorus needs.MethodsProspective observational study. Phosphate and calcium plasma concentrations and calcium balance were evaluated daily during the first week of life in very preterm infants, and their relationship with nutrition was studied. For this purpose, infants were divided into three groups: high, medium and low AA intake (HAA, MAA, LAA). A calculation formula to assess phosphorus needs was elaborated, with a theoretical model based on AA and calcium intake, and the cumulative deficit of phosphate intake was estimated.Results154 infants were included. Hypophosphatemia (12.5%) and hypercalcemia (9.8%) were more frequent in the HAA than in the MAA (4.6% and 4.8%) and in the LAA group (0% and 1.9%); both p<0.001.DiscussionCalcium-phosphorus homeostasis was influenced by the early AA intake. We propose to consider phosphorus and calcium imbalances as being part of a syndrome, related to incomplete provision of nutrients after the abrupt discontinuation of the placental nutrition at birth (PI-ReFeeding syndrome).We provide a simple tool to calculate the optimal phosphate intake. The early introduction of AA in the PN soon after birth might be completed by an early intake of phosphorus, since AA and phosphorus are (along with potassium) the main determinants of cellular growth.

Late and Insufficient Phosphorus Supplementation is Associated with Early Severe Hypophosphatemia in Extremely Low Birth Weight Infants with Early Amino Acid Administration

“…In a study by Boubred et al, 8 80% (48/60) of ELBWI experienced hypopho sphatemia, defined as a serum phosphate level <1.6 mmol/L (4.95 mg/dL), which corresponds to relatively milder hypopho sphatemia com pared to that in the present study. Bonsante et al 16 showed a clear association between high amino acid admi nistration and hypophosphatemia; hypophosphatemia was more frequent in the high amino acid group (12.5%) than in the medium (4.6%) and low amino acid groups (0%). Similarly, in the study of Ichi kawa et al, 7 higher parenteral amino acid admi nistration was associated with hypophosphatemia on day 8.…”

Early hypophosphatemia in very low birth weight preterm infants

“…In publications, hypophosphatemia is set at various phosphorus concentrations ranging from <0.8 mmol/L to ≤ 0.9 mmol/L or ≤ 1 mmol/L. 9,[14][15][16] Therefore, which level should require intensive phosphate supplementation? In other words, when should hypophosphatemia be diagnosed?…”

“…Moreover, the acceleration of anabolism results in the increased reprocessing of phosphates and potassium. 9 The clinical implication of hypophosphatemia are multi-system disorders occurring mainly in energy-active organs; thus, heart or respiratory failure, muscle hypotension, neurological symptoms, hematological disorders, insulin-resistant hyperglycemia, or metabolic acidosis may occur. However, indications for the modification of the phosphate intake of nutritional treatment, which, according to current recommendations, are introduced on the 3 rd day of a neonate's life, have not yet been established.…”

Nutrición parenteral en situaciones clínicas especiales

“…Respecto a las necesidades de fósforo y calcio, un estudio observacional con 154 RN prematuros que recibieron NP precoz agresiva (AA inicial > 2 g/kg/día), describe mayor incidencia de hipofosfatemia (9,8%) e hipercalcemia (12,5%) en la primera semana de vida, comparado con aquellos que recibieron dosis menores de AA (22), lo que obliga a la monitorización estrecha del metabolismo fosfo-cálcico en estos pacientes.…”