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17002

Hypercalcemia Occurs Frequently During the First Week of Life In Extremely Low Birth Weight Infants

Friday, October 19, 2012
Room R02-R05 (Morial Convention Center)
Amy B. Hair, MD, Angelica Lorenzo, Keli M. Hawthorne, MS, RD and Steven A. Abrams, MD, FAAP, Department of Pediatrics, Section of Neonatology, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Texas Children's Hospital, Houston, TX

Purpose

To evaluate peak ionized calcium (iCa) and total serum phosphorus (P) concentrations in infants < 1000 grams birth weight (ELBW) receiving parenteral nutrition (PN) in the first 21 days of life (DOL). 

Methods

We measured iCa and P in PN-dependent ELBW infants during the first 21 days of life in a single center, prospective observational cohort study. All infants received a standard PN as tolerated via protocol providing 1.0-1.2 mmol/kg/day of calcium given as calcium gluconate beginning on DOL 1 and advancing to 2.0 mmol/kg/day by DOL 5 with 1:1 molar ratio of phosphorus beginning on DOL 3.

Results

We evaluated 67 infants with a mean gestational age of 26.5 ± 2.0 weeks and birth weight (BW) of 785 ± 129 grams (Mean ± SD). Peak iCa was 1.37 ± 0.23 mmol/L with P of 4.1 ± 1.4 mg/dL at 4.6 ± 3.5 days. No infants were hypocalcemic. Twenty-three infants (34.3%) had a peak iCa level ≥ 1.45 mmol/L with a mean peak iCa of 1.60 ± 0.20 mmol/L occurring on DOL 5.9 ± 4.2 days. Peak iCa was positively correlated with 24 hour PN calcium (R=0.377, p=0.005) and P intake (R=0.551, p<0.001). Eight infants (11.9%) had a peak iCa ≥ 1.60 mmol/L with iCa of 1.80 ± 0.20 mmol/L and P of 3.7 ± 2.1 mg/dL on DOL 6.4 ± 5.0 days. Peak iCa was significantly higher in infants ≤ 750 grams BW compared to infants >750 grams BW (1.44 ± 0.27 mmol/L vs. 1.32 ± 0.18 mmol/L respectively, p=0.035). Seventeen (63%) infants ≤ 750 grams BW were hypercalcemic.

Conclusion

ELBW infants are at high risk for hypercalcemia especially during the first week of life when receiving standard protocol-driven PN regimens. The etiology is likely due to excessive calcium intake relative to mineral utilization in the first weeks of life. Ionized calcium should be monitored regularly in infants receiving PN, particularly in babies < 750 grams BW. Further studies should consider the physiological consequences of an elevated ionized calcium.