Measurement of true absorption, endogenous fecal excretion, urinary excretion, and retention of calcium in term infants by using a dual-tracer, stable-isotope method

Hillman, Laura S.; Johnson, Linda S.; Lee, Ding Z.; Vieira, Nancy E.; Yergey, Alfred L.

doi:10.1016/s0022-3476(05)81755-x

Cited by 22 publications

(18 citation statements)

References 24 publications

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“…These findings are similar to other reports in which no relationship was found between UCa/Cr and Ca intake [2,22,24,32]. The likely explanation for this lack of correlation is that UCa in preterm infants originates mainly from bone turnover with a relatively small percentage (12%-27%) coming from oral intake [24]. Preterm infants fed unsupplemented breast milk tend to be hypercalciuric due to PO 4 deficiency [8,9,33] and our finding of a low UCa/Cr in infants given PO 4 -supplemented EBM suggest improved bone deposition of Ca [9].…”

Section: Discussionsupporting

confidence: 92%

“…However, babies on breast milk had a significantly lower UCa/Cr ratio on multivariate analysis. These findings are similar to other reports in which no relationship was found between UCa/Cr and Ca intake [2,22,24,32]. The likely explanation for this lack of correlation is that UCa in preterm infants originates mainly from bone turnover with a relatively small percentage (12%-27%) coming from oral intake [24].…”

Section: Discussionsupporting

confidence: 90%

“…However, this latter study was carried out in infants who did not receive PO 4 supplementation and as a result were likely to be hypercalciuric [8,9]. We believe the decrease in UCa/Cr ratio with advancing PNA results from improved bone deposition of Ca [24,25,26]. The negative correlation could also be due to a decrease in urinary sodium excretion [27,28], since Ca reabsorption in the proximal tubule (50%-55%) and loop of Henle (20%-30%) parallels sodium reabsorption [29].…”

Section: Discussionmentioning

confidence: 96%

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Urinary excretion of calcium and phosphate in preterm infants

et al. 2004

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The aims of this study were to determine reference ranges for the urinary calcium (UCa/Cr) and phosphate (UPO(4)/Cr) creatinine ratios and to study factors influencing these ratios in a representative population of preterm infants managed according to current nutritional guidelines. Spot urine samples were obtained from 186 preterm infants (gestation 24-34 weeks) for measurement of UCa/Cr and UPO(4)/Cr ratios as part of a routine metabolic bone screening program, once every 2-4 weeks from the 3rd to the 18th week of life. Data were also collected on gender, appropriate or small for gestational age (SGA), nutrition [total parenteral nutrition (TPN), preterm or term formula, and breast milk], plasma Ca, P0(4), urea, and electrolytes and on the use of drugs (frusemide, dexamethasone, and theophylline). Data from infants treated with any of these three drugs were analyzed separately and not included in establishing the reference ranges for UCa/Cr and UPO(4)/Cr. The mean gestational age of the study population was 28 weeks (range 24-34 weeks). The 95th percentile for UCa/Cr at 3 weeks of age was 3.8 mmol/mmol and decreased significantly with increasing postnatal age (P<0.001). The 95th per-centile for UPO(4)/Cr was 26.69 mmol/mmol at 3 weeks of age, but this did not change significantly with increasing postnatal age (P=0.296). On univariate analysis there was no significant association of UCa/Cr and UPO(4)/Cr with gender and type of enteral nutrition. The UCa/Cr was lower in infants who were SGA (P=0.013) and with low plasma Ca (P=0.008). Infants on TPN had significantly higher UCa/Cr (P =0.019) and lower UPO(4)/Cr ratios(P<0.001). Multivariate analysis confirmed the decrease in UCa/Cr ratio with increasing postnatal age, but the SGA effect was eliminated. The use of furosemide(P<0.001) and theophylline (P=0.003) was associated with a significant increase in the UCa/Cr ratio. The use of dexamethasone was also associated with an increase in UCa/Cr ratio, but this did not achieve statistical significance (P=0.339). The use of furosemide, theophylline,and dexamethasone had no effect on UPO(4)/Cr. We report a reference range for UCa/Cr and UPO(4)/Cr ratios and factors influencing these ratios in a representative population of preterm infants between 24 and 34 weeks gestation, managed according to current nutritional guide-lines.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 96%

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Urinary excretion of calcium and phosphate in preterm infants

et al. 2004

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“…Preterm infants absorb only a percentage of the Ca contained in formula milk, and show low urinary Ca concentration, along with high P excretion to dispose of the P which cannot be used for bone formation [2] . Some researchers have proposed careful monitoring of urinary mineral excretion and individually adjusted supplementation [13,14] .…”

Section: Discussionmentioning

confidence: 99%

Urinary Mineral Excretion in Preterm Neonates during the First Month of Life

Giapros¹,

Papaloukas²,

Andronikou³

2006

Neonatology

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Background: Estimation of urinary parameters in preterm infants is a useful method for identifying metabolic derangements. Objectives: A prospective, longitudinal, hospital-based study was designed to examine the variability and the associations in renal excretion of calcium (Ca), magnesium (Mg), phosphate (P) and sodium (Na) in formula-fed preterm infants during the first month of life. Patients: Thirty-four infants <32 weeks gestational age, clinically stable, not receiving nephrotoxic drugs. Methods: Measurements of serum and 8-hour urinary mineral and creatinine (Cr) concentrations were made in all infants during three periods (at 7–10, 14–17 and 21–26 days postnatally). The urinary parameters, FENa, FEP, UCa/UCr, UMg/UCr were calculated. 24- hour urinary excretion was estimated by extrapolation of the 8-hour values. Results: The 24-hour excretion values (median and range) (mmol/kg) during the three study periods were, respectively, for Ca: 0.027 (0.015–0.15), 0.030 (0.007–0.12), 0.031 (0.008–0.12), for P: 0.26 (0.07–0.83), 0.29 (0.06–0.67), 0.41 (0.22–0.70), for Mg: 0.025 (0.007–0.14), 0.025 (0.008–0.16), 0.027 (0.010–0.10) and for Na: 2.85 (0.8–15), 1.45 (0.3–17), 1.56 (0.6–4.3). Na excretion declined while the excretion of the other minerals remained stable. A positive correlation was observed between excretion of Ca, Mg and Na (Ca vs. Na r = 0.63, p < 0.0001; Ca vs. Mg r = 0.65, p < 0.0001; Na vs. Mg r = 0.38, p = 0.012) as well as between the renal parameters FENa, FEP, UCa/UCr, UMg/UCr and the respective 24-hour excretion values (r = 0.80, 0.86, 0.84, 0.81) Conclusions: Urinary excretion of Ca, P, and Mg in preterm formula-fed infants is stable during the first month of life while urinary Ca, Na and Mg are closely correlated during the same period.

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“…12,13 To date, studies in healthy human infants have not assessed the contribution of individual intestinal segments to calcium absorption. 14,15 Studies in adult rodents have examined the contribution of intestinal segments to net absorption. In rats, Ussing chamber studies on duodenum revealed net absorption of calcium while net secretion has been observed in the jejunum and ileum.…”

Section: Intestinal Absorptionmentioning

confidence: 99%

Intestinal absorption and renal reabsorption of calcium throughout postnatal development

Beggs

Alexander

2017

Exp Biol Med (Maywood)

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This mini review outlines the current state of knowledge pertaining to the molecules and mechanisms maintaining a positive calcium balance throughout postnatal development. This process is essential to achieving optimal bone mineral density in early adulthood, thereby lowering the lifetime risk of osteoporosis. AbstractCalcium is vital for many physiological functions including bone mineralization. Postnatal deposition of calcium into bone is greatest in infancy and continues through childhood and adolescence until peek mineral density is reached in early adulthood. Thereafter, bone mineral density remains static until it eventually declines in later life. A positive calcium balance, i.e. more calcium absorbed than excreted, is crucial to bone deposition during growth and thus to peek bone mineral density. Dietary calcium is absorbed from the intestine into the blood. It is then filtered by the renal glomerulus and either reabsorbed by the tubule or excreted in the urine. Calcium can be (re)absorbed across intestinal and renal epithelia via both transcellular and paracellular pathways. Current evidence suggests that significant intestinal and renal calcium transport changes occur throughout development. However, the molecular details of these alterations are incompletely delineated. Here we first briefly review the current model of calcium transport in the intestine and renal tubule in the adult. Then, we describe what is known with regard to calcium handling through postnatal development, and how alterations may aid in mediating a positive calcium balance. The role of transcellular and paracellular calcium transport pathways and the contribution of specific intestinal and tubular segments vary with age. However, the current literature highlights knowledge gaps in how specifically intestinal and renal calcium (re)absorption occurs early in postnatal development. Future research should clarify the specific changes in calcium transport throughout early postnatal development including mediators of these alterations enabling appropriate bone mineralization.

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Measurement of true absorption, endogenous fecal excretion, urinary excretion, and retention of calcium in term infants by using a dual-tracer, stable-isotope method

Cited by 22 publications

References 24 publications

Urinary excretion of calcium and phosphate in preterm infants

Urinary excretion of calcium and phosphate in preterm infants

Urinary Mineral Excretion in Preterm Neonates during the First Month of Life

Intestinal absorption and renal reabsorption of calcium throughout postnatal development

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