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Indian Pediatr 2016;53: 1023-1024 |
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Vitamin D and Metabolic
Bone Parameters in Preterm Neonates
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*Amitoj Singh Chhina, Arvind Shenoi,
#Namrata Nagendra, Nilesh Rao
and Malathi Raja
From the Departments of Neonatology and #Obstetrics
and Gynecology, Cloudnine Hospital, Old Airport Road,
Bangalore, Karnataka, India.
Email: [email protected]
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We measured serum levels of 25-hydroxy vitamin D (25(OH) D) in 79
preterm neonates (
£32
wk), and correlated it with serum ionized calcium (Ca++) levels at 48-72
h and serum phosphorus and alkaline phosphatase levels at 2-3 weeks of
age. The mean (SD) 25 (OH)D level was 14.8 (7.0) ng/mL. 25(OH)D levels
had a weak positive correlation with Ca++ (r=0.299) and phosphorus
(r=0.186), and a negative correlation with alkaline phosphatase
(r=-0.523).
Keywords: Hypocalcemia, Neonate, Prematurity.
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O
steopenia or metabolic bone disease of
prematurity has been reported in 55% of extremely low birth weight
(ELBW) and 23% of very low birth weight (VLBW) infants [1]. Low
phosphorus and high alkaline phosphatase (ALP) are highly sensitive and
specific for diagnosing osteopenia of prematurity [1].
Although studies from around the world have reported
that preterm infants are deficient in vitamin D at birth [2-6], exact
role of active form of vitamin-D in fetal bone mineralization is
unclear. Chronic maternal vitamin D deficiency has been shown to
adversely affect fetal skeletal development [7]. Preterm infants may
have reduced Vit D stores as early delivery may curtail the
transplacental transfer that happens between 25 weeks of gestation and
term. Maternal deficiency may further restrict the transplacental
transfer [7].
We conducted a cross-sectional study at a
tertiary-level neonatal unit in Bangalore, Southern India, to determine
the 25(OH)D levels of preterm infants
£32 weeks at 48-72
hours and correlate them with serum ionized calcium (Ca++)
levels at 48-72 hours of life and serum phosphorus and ALP levels at 2-3
weeks postnatal age. The 25(OH)D levels were determined using
chemiluminescent microparticle immunoassay (ARCHITECT i1000SR, Abott
Diagnostics, Lake Forest, IL, USA). Ca++
levels were measured using potentiometry (Gem Premier 3000,
Instrumentation Laboratory, Bedford, MA, USA). Phosphorus levels were
measured using spectrophotometry (BioSystems BTS 350, Quezon City,
Philippines). ALP levels were determined using absorbance photometry (Cobas
C 111, Roche Diagnostics Limited, Rotkreuz, Switzerland).
Seventy-nine preterm neonates were included in the
study. The mean (SD) gestational age (GA) and birth weight were 29.8
(2.5) weeks and 1438.1 (464.8) g, respectively. The mean (SD) 25(OH)D
level was 14.8 (7) ng/mL (Table I). Forty-eight (60.8%)
neonates had Ca ++ levels <1
mmol/L, 32 (40.6%) had phosphorus levels <4 mg/dL, and 31 (39.2%) had
ALP levels >500 U/L. All the infants had Ca++
³1 mmol/L at
2-3 weeks. Weak positive correlation was found between 25 (OH) D and Ca++
(r= 0.299, P<0.05), and also 25 (OH) D and phosphorus (r=0.186,
P=0.101). Moderate negative correlation was found between vitamin
D and ALP (r=-0.523, P<0.05). Weak correlation was also found
between GA and 25(OH)D (r=0.422, P<0.05), GA and phosphorus
(r=0.495, P<0.05), and GA and ALP (r=-0.523, P<0.05).
TABLE I Serum 25-hydroxy Vitamin D, Calcium and Phosphorus in Preterm Neonates
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Characteristics |
All infants (n=79) |
Infants born <28 weeks (n=17) |
Infants 28-32 weeks (n=62) |
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Males |
44 (55.7) |
7 (41.2) |
37 (59.7) |
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Gestational age (weeks)* |
29.8 (2.5) |
25.6 (1.3) |
31 (1.2) |
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Birth weight (g)* |
1438.1(464.8) |
842.9(168.9) |
1601.3 (378.1) |
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25(OH)D at 48-72 (ng/mL)* |
14.8 (7) |
10.1 (5.6) |
16.1 ( 6.9) |
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Infants with 25(OH)D <30 ng/mL |
78 (99.9) |
17 (100) |
61 (98.4 ) |
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Infants with 25(OH)D <20 ng/mL |
59 (74.7) |
16 (94.1) |
43 (69.3) |
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Infants with 25OHD <10 ng/mL |
31 (39.2) |
10 (58.8) |
21 (33.9) |
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Ca++ at 48-72 hours (mmol/L)* |
0.95 (0.13) |
0.91 (0.13) |
0.96 (0.13) |
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Phosphorus at 2-3 weeks (mg/dL)* |
4.1 (1.1) |
3.1 (1) |
4.4 (0.9) |
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ALP at 2-3 weeks (U/L)* |
460.7 (160.5) |
597 (188.7) |
423.3 (138.2) |
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Values in No. (%) or * mean (SD). |
Potential limitations of the study include lack of
the maternal 25(OH)D levels and neonatal parathyroid hormone levels; the
neonatal 25(OH)D levels at 2-3 weeks; and bone mineral density readings.
Preterm neonates born at
£32 weeks, especially
<28 weeks tend to have low Vitamin D levels and hypocalcemia at 48-72
hours of life, and may develop hypophosphatemia and elevated ALP levels
at 2-3 weeks, but a strong correlation could not be elicited between
these parameters.
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