Sunshine exposure and serum 25-hydroxyvitamin D concentrations in exclusively breast-fed infants

The relationship between serum 25-hydroxyvitamin D (25-OHD) concentrations and sunshine exposure in 61 term, exclusively breast-fed infants younger than 6 months of age was investigated. Sunshine exposure was quantitated using a sunshine and clothing diary, which was verified by infant-adapted ultraviolet dosimetry. By multiple regression techniques, infant serum 25-OHD concentrations were significantly related to UV exposure and maternal serum 25-OHD concentrations. Infant 25-OHD concentrations correlated with sunshine exposure in infants whose mothers had low (less than 35 ng/ml) or high (greater than 35 ng/ml) serum concentrations of 25-OHD (r = 0.70, P less than 0.001 and r = 0.53, P = 0.004, respectively). Estimates were made to determine sunshine exposure conditions necessary to maintain serum 25-OHD concentrations above the lower limit of the normal range (11 ng/ml). A conservative estimate would be 30 minutes per week wearing only a diaper or 2 hours a week fully clothed without a hat.     

Serum concentrations of vitamin D metabolites in exclusively breast-fed infants at 70 degrees north

The effect of prolonged breast-feeding on the serum concentrations of vitamin D metabolites, calcium, phosphate, and alkaline phosphatase was studied longitudinally in 7 infants from Northern Norway. They were exclusively breast-fed for a median of 7 1/2 months. Three of the mothers were supplemented with vitamin D throughout lactation. All but one of the infants had 25-hydroxyvitamin D (25-OHD) levels in the rachitic range (less than 20 nmol/l) on at least one occasion. Vitamin D supplementation of the mother had no apparent effect on the infants' 25-OHD levels, but the values increased during summer. The infant who had the lowest 25-OHD levels also had decreased 1,25-dihydroxyvitamin D (1,25-(OH)2D) concentrations, while the others maintained 1,25-(OH)2D levels within normal limits. 24,25-(OH)2D concentrations were undetectable when the 25-OHD levels were below 35 nmol/l, but the two metabolites were closely correlated for higher values of 25-OHD. Low 25-OHD levels were associated with decreased phosphate concentrations at 6 months. The calcium levels were normal throughout the study period of one year, as were all but two of the alkaline phosphatase values. Although none of the infants had clinical or biochemical evidence of rickets, the results suggest that the vitamin D supply from human milk is inadequate, and that routine vitamin D supplementation is advisable for breast-fed infants who are deprived of sunlight exposure.     

Low serum 25-hydroxyvitamin D levels and bronchiolitis severity in Spanish infants

This cross-sectional study was performed to examine the prevalence of hypovitaminosis D in infants with acute bronchiolitis compared with control subjects and to evaluate the relationship between serum 25-hydroxyvitamin D (25(OH) D) and the severity of bronchiolitis. Serum 25(OH) D levels were measured by radioimmunoassay in 48 infants with acute bronchiolitis (2.5?±?2.0 months) and in 30 healthy infants (3.2?±?2.3 months). 25(OH) D levels (ng/ml) in children with acute bronchiolitis were significantly lower than in the control group (median 29.9 ng/ml (interquartile range (IQR) 21.4–37.5) versus median 38.2 ng/ml ((IQR 26.1–48.1), p?=?0.022), mainly in infants with moderate–severe bronchiolitis (median 29.8 ng/ml, IQR 19.2–35.9). The prevalence of hypovitaminosis D was remarkably greater among infants with bronchiolitis than in control subjects (52.1 versus 26.6 %). A significant inverse correlation was found between serum 25-hydroxyvitamin D levels and disease severity (rho?=??0.457, p?<?0.001). Conclusion: The prevalence of hypovitaminosis D is high in Spanish infants with bronchiolitis. The severity of acute bronchiolitis increases with a decline in serum 25 (OH) D level.     

Evaluation of 25-hydroxyvitamin D and vitamin D binding protein losses in thirteen children on continuous ambulatory peritoneal dialysis

Thirteen children, 6 females, 7 males, aged 2 to 13 years were studied. At the time of study they were on continuous ambulatory peritoneal dialysis (CAPD) for 1 to 22 months. 25-(OH)D loss in daily dialysate fluids represented 2 to 22 micrograms/day. A significant correlation was found between 25-(OH)D plasma concentration and 25-(OH)D dialysate concentration. 25-(OH)D clearance was correlated to 25-(OH)D binding protein clearance (p less than 0.001). These findings of important 25-(OH)D losses in the dialysate fluid of children on CAPD demonstrate the necessity of carefully adapted vitamin D intakes with such a treatment.     

血清25-羟维生素D在佝偻病诊断中的应用价值

目的：探讨血清25 羟维生素D［25（OH）D］在维生素D缺乏性佝偻病早期诊断中的意义。方法：检测对照组（73例）、可疑组（45例）和佝偻病组（65例）的血清25（OH）D、钙、磷、碱性磷酸酶浓度,并通过ROC曲线对血清25（OH）D的诊断价值进行评价。结果：对照组、可疑组和佝偻病组的血清25（OH）D水平分别为112±37、83±30和72±31 nmol/L,后两者均显著低于对照组（F=26.174,P0.05）。可疑组和佝偻病组的维生素D缺乏率均显著高于对照组（χ2=33.346, P0.05）。结论：血清25(OH)D水平在可疑及确诊佝偻病的患儿中显著降低,可以反映维生素D的营养状况,适用于佝偻病的早期筛查。     

Hypocalcemia due to vitamin D deficiency in exclusively breastfed infants

This report is based on observations during the conduct of a study of hypocalcemia in infants and children. In a study of 50 cases, 13 exclusively breast fed infants manifesting with hypocalcemic seizures were confirmed to have vitamin D deficiency. None of the 13 infants had received vitamin D supplementation. All of them had biochemical evidence of hyperparathyroidism and low levels of 25 (OH) Vit D3 and promptly responded to therapy with vitamin D and calcium. All the mothers of these 13 infants had low levels of 25 (OH) Vit D3. Mothers of 5 infants had reported reduced exposure to sunlight due to religious reasons. This report emphasizes the need to supplement Vitamin D in exclusively breast fed infants and also to encourage exposure to sunlight in them and their mothers.     

Effect of season and vitamin D supplementation on plasma concentrations of 25-hydroxyvitamin D in Norwegian infants

Plasma concentrations of 25-hydroxyvitamin D (25OHD) were determined in 81 vitamin D supplemented or unsupplemented infants at the end of winter. The values were compared with maternal levels and with concentrations found in 22 unsupplemented infants at the end of summer. The 25OHD levels of the neonates were lower, but closely related to maternal values (r = 0.95, p less than 0.0005). Unsupplemented breast-fed infants had lower 25OHD levels at 6 weeks than at 4 days (16 +/- 7 vs. 32 +/- 15 nmol/l, mean +/- 1 SD, p less than 0.0005). The mean 25OHD level of vitamin D supplemented 6-12 months old infants was intermediate between those of the unsupplemented nursed groups and the unsupplemented children studied during summer (53 +/- 28 vs. 85 +/- 28 nmol/l, p less than 0.0005). Six weeks old infants who had received a milk formula containing 400 IU vitamin D3 per liter had levels similar to the latter group (92 +/- 21 nmol/l). The data suggest that the vitamin D stores acquired during fetal life, or from ultraviolet light exposure during the summer, may be inadequate to maintain safe levels of 25OHD throughout the winter, but that a daily supplement of 400 IU is adequate to establish concentrations in the summer range.     

25-hydroxyvitamin D and calcium levels in maternal, cord and infant serum in relation to maternal vitamin D intake

The plasma levels of 25-hydroxyvitamin D (25-OHD), total calcium, phosphorus and proteins were measured in 40 healthy mothers and their infants at the time of delivery during the months of December and January. Calcium, phosphorus and proteins were again measured in the plasma of the infants on the fourth day of life. Vitamin D intake of the mothers during their last 3 months of pregnancy were estimated by interviews. The mean (+/-SE) plasma levels of 25-OHD was 9.0 +/- 0.9 ng/ml in the mothers and 5.05 +/- 0.4 ng/ml in cords. There was a significant correlation between mother and cord plasma levels (r = 0.75, p less than or equal to 0.001). The concentration gradient of 25-OHD plasma levels between mother and cord is higher at high 25-OHD maternal concentrations. This suggests that the placenta plays a regulating role in the 25-OHD transfer between mother and foetus. The 4-day-old infants from mothers having a suboptimal vitamin D intake (less than 150 IU/day) have a lower mean serum plasma level than infants born from mothers with a vitamin D intake of more than 500 IU/day.     

The plasma levels of 25-hydroxyvitamin D in patients with various liver diseases and the response of 25-hydroxyvitamin D to vitamin D treatment.

The mean plasma levels of 25-hydroxyvitamin D (25-OH-D) were measured before and after the administration of 2000 units of daily oral vitamin D2 for a period of 2 weeks in 9 normal infants and children, 7 infants with neonatal hepatitis and persistent neonatal hepatitis, and 4 infants with congenital biliary atresia. The mean plasma level of 25-OH-D increased significantly from 19.5 +/- 3.7 (S.E.) ng/ml to 34.0 +/- 6.8 (S.E.) ng/ml after administration of vitamin D2 in controls (p less than 0.05). The mean plasma level of 25-OH-D also increased from 8.0 +/- 2.1 (S.E.) ng/ml to 22.1 +/- 2.6 (S.E.) ng/ml after vitamin D treatment in hepatitis group (p less than 0.05). In patients with congenital biliary atresia, vitamin D treatment did not affect eh plasma levels of 25-OH-D.     

Serial serum 25-hydroxyvitamin D and mineral homeostasis in very premature infants fed preterm human milk

Fourteen very low birthweight infants (mean +/- SD 1,070 +/- 180 g and 29.3 +/- 1.9 weeks gestation) fed their own mother's milk were clinically followed until 3-4 months of age with frequent measurements of serum calcium, phosphorus, magnesium, 25-hydroxyvitamin D (25-OHD), parathyroid hormone, alkaline phosphatase, and albumin, and urine calcium, phosphorus, and magnesium. These infants were matched for birthweight and gestation with 14 infants (1,075 +/- 152 g and 29.0 +/- 1.7 weeks) who had been similarly followed during concomitant studies of infants fed standard formula (Similac 20 cal/oz). Urine phosphorus was markedly lower in the breast milk-fed group from initiation of feedings, and serum phosphorus became significantly lower at and after 6 weeks of age. The fall in serum phosphorus was accompanied by a marked calciuria. Parathyroid hormone was suppressed in the breast milk-fed group, although serum calcium was not elevated and did not differ from formula-fed infants. A high incidence of moderate-severe hypomineralization on radiographs was seen in both breast milk- and formula-fed groups. Six of 14 breast-fed infants required phosphorus supplementation at 8-10 weeks of age because of significant hypophosphatemia, hypercalciuria, and hypomineralization. These infants differed from those not requiring phosphorus supplements by being smaller at birth but not of lower gestation, and having persistently low serum 25-OHD at and after 6 weeks of age.     

Decreased bone mineral content in small-for-gestational-age infants compared with appropriate-for-gestational-age infants: normal serum 25-hydroxyvitamin D and decreasing parathyroid hormone

Bone mineral content was determined by photon absorptiometry, adapted for use in neonates, in 23 small-for-gestational-age (SGA) infants of 31 to 42 weeks of gestational age, for 12 weeks. At birth, term SGA infants had lower bone mineral content than term appropriate-for-gestational-age (AGA) infants; postnatal increase in bone mineral content was slow and lagged significantly behind that of term AGA infants. Preterm SGA infants had bone mineral content that was similar to that of preterm AGA infants at birth; postnatal bone mineral content was similar to that of preterm AGA infants, but was decreased compared with the expected intrauterine bone mineral content. Serum 25-hydroxyvitamin D concentrations and parathyroid hormone levels were the same for SGA and AGA infants. Serum 25-hydroxyvitamin D concentrations decreased slightly with postnatal age and remained within normal limits. Serum parathyroid hormone concentrations decreased in both SGA and AGA infants and reached undetectable levels at 10 to 12 weeks of age.     

Hypovitaminosis D and vitamin D deficiency in exclusively breast-feeding infants and their mothers in summer: a justification for vitamin D supplementation of breast-feeding infants

OBJECTIVE: To determine the prevalence of hypovitaminosis D in exclusively breast-feeding infants and their mothers in a community where maternal sunshine exposure is low. STUDY DESIGN: Serum levels of calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D (25-OHD), and intact parathyroid hormone were measured in 90 unsupplemented healthy term breast-feeding Arab/South Asian infants and their mothers in summer. Maternal dietary vitamin D intake was also estimated. RESULTS: The median age of infants was 6 weeks. The median serum 25-OHD concentrations in mothers (8.6 ng/mL) and infants (4.6 ng/mL) were low, and 61% of the mothers and 82% of the 78 infants tested had hypovitaminosis D (serum 25-OHD <10 ng/mL). The infants with hypovitaminosis D had elevated serum alkaline phosphatase and a tendency to higher serum intact parathyroid hormone levels. The average daily maternal vitamin D intake from commercial milk was 88 IU. CONCLUSIONS: Hypovitaminosis D is common in summer in exclusively breast-feeding infants and their mothers. The results provide justification for vitamin D supplementation of breast-feeding infants and mothers in the United Arab Emirates. Low vitamin D intake probably contributed to low maternal vitamin D status.     

Mineral homeostasis in very premature infants: serial evaluation of serum 25-hydroxyvitamin D, serum minerals, and bone mineralization

This study was designed to evaluate the role of vitamin D sufficiency, as reflected in serum 25-hydroxyvitamin D (25-OHD) concentrations, on serum minerals and bone mineralization in very premature infants. Seventy-two infants (mean +/- SD gestation 30.1 +/- 2.5 weeks, mean +/- SD birth weight 1178 +/- 278 gm) were observed serially for the first 3 months of life. Mean serum calcium and phosphorus values, but not magnesium, remained low prior to 12 weeks. The percentage of infants with moderate to severe hypomineralization was 75% at 3 weeks, 55% at 6 weeks, 54% at 9 weeks, and 15% at twelve weeks. Low serum calcium and phosphorus values, high alkaline phosphatase activity, and moderate-severe hypomineralization were more frequent in infants weighing less than 1000 gm and in those with lower mineral intake. With a 400 IU vitamin D supplement, 45% of infants could maintain an initially normal serum 25-OHD concentration or increase low concentrations, whereas 55% had falling or persistently low (less than or equal to 15 ng/ml) 25-OHD concentrations. Birth weight and mineral intakes were comparable in these two groups, yet the group with the lower serum 25-OHD concentration had lower serum calcium and higher alkaline phosphatase values, and a higher percentage of moderate to severe hypomineralization. Regardless of birth weight, mineral intake, or 25-OHD concentration, increases in serum calcium and phosphorus values and in mineralization were seen at postconception term (12 weeks in most infants, nine weeks in those weighing 1250 to 1600 gm). At 12 weeks of age, but not before, serum 25-OHD concentration was directly correlated with serum calcium (r = 0.47, P less than 0.01) and serum phosphorus (r = 0.47, P less than 0.01) and inversely correlated with alkaline phosphatase values (r = -0.71, P less than 0.01). Mineral availability and 25-OHD sufficiency both appear to be important and to act synergistically, with neither totally compensating for the other.     

Perinatal vitamin D metabolism. II. Serial 25-hydroxyvitamin D concentrations in sera of term and premature infants.

Serial concentration values of 25-hydroxyvitamin D (25-OHD) were determined in the sera of term, premature, and twin infants. In infants born at term with normal concentrations of 25-OHD in cord blood, serial concentrations of 25-OHD remained normal; in infants born at term with low concentrations of 25-OHD in cord blood, serial concentrations of 25-OHD increased. In premature infants with normal concentrations of 25-OHD in cord blood, serial concentrations of 25-OHD decreased; in premature infants with low values of 25-OHD in cord blood, serial concentrations of 25-OHD did not increase until a postconceptual age of 36 to 38 weeks. The concentrations of 25-OHD in the sera of twin infant pairs followed parallel courses. Oral and intravenous supplementation of vitamin D did not significantly increase the concentrations of 25-OHD in serum of premature infants. These findings suggest that a decreased rate of 25-hydroxylation of vitamin D may be a factor impairing homeostasis of 25-OHD in premature infants.     

Heightened attention to supplementation is needed to improve the vitamin D status of breastfeeding mothers and infants when sunshine exposure is restricted

Although exclusively breastfed infants are at increased risk of vitamin D (vit D) deficiency if vit D supplementation is lacking and sun exposure is limited, assessment of both risk factors in the first year of life is lacking. We evaluated the contribution of vit D intake and sunlight exposure to vit D status in 120 healthy, breastfeeding mother–infant dyads, who were followed up for 1 year. Vitamin D intake and skin sunlight exposure were evaluated using questionnaires. Serum 25‐hydroxyvitamin D, parathyroid hormone (PTH) and alkaline phosphatase levels were determined post‐natally in mothers at 4 weeks and in infants at 4, 26 and 52 weeks. Vitamin D supplementation was low (<20%) and sunlight exposure was common (93%) in study infants. At 4 weeks, 17% of mothers were vit D deficient (<50 nmol L^?1) and 49% were insufficient (50–<75 nmol L^?1), while 18% of infants were severely vit D deficient (<25 nmol L^?1) and 77% were deficient (<50 nmol L^?1). At 26 weeks, winter/spring birth season and shorter duration of months of exclusive breastfeeding were protective of vit D deficiency in infants. Vitamin D deficiency in infants decreased to 12% at 52 weeks with sunlight exposure. Serum PTH levels were significantly higher in severely vit D deficient than sufficient infants. Vitamin D deficiency was widespread in early post‐partum breastfeeding mothers and infants, and declined to one in eight infants at 52 weeks due mostly to sunshine exposure. When sunlight exposure is limited or restricted, intensified vit D supplementation of breastfeeding mothers and infants is needed to improve vit D status.     

Sunlight exposure and vitamin D status in breastfed infants

Objective

To correlate the sunlight exposure in first 6 months to vitamin D status at 6 months of age in predominantly breastfed infants; and to quantify the sunlight exposure required to achieve serum 25(OH)D level >20 ng/mL, by 6 months of age

Design

Prospective cohort.

Setting

Tertiary-care hospital predominantly catering to urban poor population in Delhi.

Participants

132 healthy infants, delivered at term, and predominantly breastfed were enrolled at 6-8 weeks of age. Of these, 100 infants were available for final evaluation at 6 months of age (mean (SD) follow-up: 126 (17) days).

Methods

Baseline maternal vitamin D (serum 25(OH)D) levels were obtained at enrolment. The mothers were asked to maintain a daily record of duration of sunlight exposure, timing of exposure, and body surface area exposed, for the infant, on a pre-designed proforma, till the child was 6 months of age. Infant’s serum 25(OH)D was measured at 6 months of age.

Main outcome measures

Cumulative Sun Index was calculated as a composite measure of overall duration/time/body surface area exposed to sunlight; and correlated with the infant serum 25(OH)D after adjusting for baseline maternal serum 25(OH)D levels, season of exposure, and skin color of the infant. Sun index for exposure in morning (before 10 am) and afternoon (10 am-3 pm) were also correlated to vitamin D status.

Results

Of 100 mother-infant pairs completing the study, 90 mothers had vitamin D deficiency (serum 25(OH)D <12 ng/mL). The median duration of exposure of infants to sunlight was 17 min per week, on 6% of body surface area. Vitamin D levels of 67 (67%) infants at 6 months were less than 12 ng/mL and another 23% had insufficient levels (12-20 ng/mL). Cumulative sun index correlated positively to infant’s serum 25(OH)D level at 6 months of age (r= 0.461, P<0.001). Increment in afternoon sun index by 1 unit increased the serum 25(OH)D level by 1.07 ng/mL (95% CI 0.37, 1.78; P= 0.003). A minimum 30 minute weekly afternoon sunlight exposure, between 10 am and 3 pm, over 40% body area (infant clothed in diapers, in prone position) for at least 16 weeks, was estimated requirement to achieve sufficient vitamin D levels (>20 ng/mL) by 6 months of age.

Conclusions

There is a significant positive correlation between afternoon sunlight exposure and infant’s vitamin D levels, independent of maternal vitamin D status. Randomized controlled trials are suggested to explore the effectiveness of this simple intervention to prevent or treat vitamin D deficiency in children.