Results of Extremely‐low‐birth‐weight Infants Randomized to Receive Extra Enteral Calcium Supply

Abstract

Background Bone mineral deficiency continues to occur in extremely low birth weight (ELBW) infants despite formulas enriched in Ca and P. Objective This study tested whether extra enteral Ca supplementation increases bone mineral content (BMC) and prevents dolichocephalic head flattening and myopia in ELBW infants. Study design Infants 401–1000 birth weight receiving enteral feeds were randomized to receive feeds supplemented with Ca-gluconate powder, or pure standard feeds. Main outcome measures were the excretion of Ca and P by weekly spot urine measurements, the degree of dolichocephalic deformation (fronto-occipital to biparietal diameter ratio, FOD/BPD) at 36 weeks postmenstrual age and the BMC (by dual-energy x-ray absorptiometry) at discharge. Cycloplegic refraction was measured at 18–22 months corrected age. Results Ninety-nine ELBW infants with a gestational age of 26 weeks (23–31) [Median (minimum-maximum)] were randomized at a postnatal age of 12 days (5–23) weighing 790g (440–1700). Urinary Ca excretion increased, P excretion decreased in the Ca supplemented group. Total body BMC was 89.9 ± 2.4 g (mean ± SE) in the supplemented group and 85.2 ± 2.6 g in the control group (p= 0.19). The FOD/BPD was 1.50 (1.13–1.69, mean ± SD) and 1.47 (1.18–1.64) in the supplemented and control groups, and the refraction 0.98 ± 1.23 and 1.40 ± 1.33 dpt. (p=0.68), respectively in 64 ELBW infants (79% of survivors) at 2-year-follow-up. Conclusions Extra enteral Ca supplementation did not change BMC, head shape or refraction. The decreased P excretion may reflect P deficiency in infants receiving extra Ca, preventing improved bone mineral accretion.

Update on Calcium and Phosphorus Requirements of Preterm Infants and Recommendations for Enteral Mineral Intake

“…For instance, dipotassium phosphate as supplement has been shown to reduce Ca absorption from formula (P source: tribasic calcium phosphate and nonfat dry milk) in a balance study [ 52 ]. In a second study, dipotassium phosphate as a formula component prevented the absorption of Ca from Ca-gluconate as a supplement, possibly because precipitation limited the bioavailability of both Ca and inorganic P [ 55 ]. On the other hand, organic Ca and P salts have been used successfully (Ca-gluconate and Na 2 -glycerophosphate) [ 54 ].…”

Role of Vitamin D in Near Sightedness

“…One theory is that, as deficiency of Vitamin D leads to alteration of intracellular Ca level and subsequently causes impaired contraction and relaxation of the ciliary muscles thus leading to myopia 18 . Another theory is Calcium deficiency secondary to lack of adequate Vitamin D levels leading to head and orbit deformity and consequently myopia of prematurity but against this was the finding of no change in refractive status of low birth weight infants after extra-enteral Ca supplementation 18 . Vitamin D is also thought to affect pathological scleral growth and myopia via retinoic acid.…”

Die Frühgeborenenosteopenie – Pathophysiologie und Diagnostik

“…0,5–1 mmol/kg/d erhöht werden. In randomisierten Studien, in denen teilweise enterale Kalziumgaben von bis zu 9,15 mmol/kg/d bei Kindern mit einem Gewicht < 1000 g verwendet wurden, waren keine vermehrten gastrointestinalen Nebenwirkungen beobachtet worden 30 .…”

“…die aktuelle Substitution zu reduzieren, ohne dass auch hierzu eine ausreichende Evidenz besteht. den, waren keine vermehrten gastrointestinalen Nebenwirkungen beobachtet worden [30].…”