Phosphate Concentrations and Modifying Factors in Healthy Children From 12 to 24 Months of Age

Abstract

Context Phosphate homeostasis and its modifiers in early childhood are inadequately characterized. Objective To determine physiological plasma phosphate concentration and modifying factors in healthy infants at 12 to 24 months of age. Design This study included 525 healthy infants (53% girls), who participated in a randomized vitamin D intervention (VIDI) trial and received daily vitamin D3 supplementation of either 10 or 30 μg from age two weeks to 24 months. Biochemical parameters were measured at 12 and 24 months. Dietary phosphate intake was determined at 12 months. Main Outcome Measures Plasma phosphate concentrations at 12 and 24 months of age. Results Mean (SD) phosphate concentration decreased from 12 months (1.9±0.15 mmol/L) to 24 months (1.6±0.17 mmol/L) of age (p<0.001 for repeated measurements). When adjusted by covariates, such as body size, creatinine, 25OHD, intact and C-terminal FGF23, mean plasma phosphate was higher in boys than girls during follow-up (p=0.019). Phosphate concentrations were similar in the vitamin D intervention groups (p>0.472 for all). Plasma iron was associated positively with plasma phosphate at both time points (B, 0.006 and 0.005, 95% CI 0.004 to 0.009 and 0.002 to 0.008, p<0.001 at both time points, respectively). At 24 months of age, the main modifier of phosphate concentration was plasma creatinine (B, 0.007, 95% CI 0.003 to 0.011, p<0.001). Conclusion Plasma phosphate concentration decreased from age 12 to 24 months. In infants and toddlers, the strongest plasma phosphate modifiers were sex, iron, and creatinine, whereas vitamin D supplementation did not modify phosphate concentrations.

Mild Hypophosphatemia-Associated Conditions in Children: The Need for a Comprehensive Approach

“…In adults, hypophosphatemia is relatively frequent in daily medical practice [20][21][22][23], but, in contrast, there are few studies assessing the leading causes of pediatric hypophosphatemia [1,13]. In our study, we found that mild hypophosphatemia is not so rare in the pediatric age.…”

“…Phosphate entails approximately 0.6% of the total weight of animals and plants [10]. It is considered the second most abundant mineral in the human body, representing about 0.5% of total infant weight [11] and nearly 1% of total weight in adults [10,[12][13][14]. It is necessary for many different vital processes, such as energy metabolism, the synthesis of DNA and RNA, and the regulation of proteins by phosphorylation [12,13,[15][16][17][18][19].…”

An Expert Perspective on Phosphate Dysregulation With a Focus on Chronic Hypophosphatemia

“…(1) Phosphate requirements vary with age and sex because of changing developmental and physiologic needs (Table 1). (15)(16)(17) The age-associated decline in serum phosphate levels, more predominantly shown in men after middle age, reflects changes in renal tubular phosphate reabsorption postulated by agedependent changes in tubular phosphate handling or levels of hormonal modulators (eg, PTH, phosphatonins, and growth hormone). (18)(19)(20)…”

“…(3,7,15,27) Rare genetic disorders of Iron and creatinine are modifying factors for plasma phosphate concentrations. (17) Source: Mayo clinic (https://www.mayocliniclabs.com/testcatalog/Clini cal+and+Interpretive/8408). hyperphosphatemia include familial tumoral calcinosis (associated with reduced intact FGF23 levels) and hypoparathyroidism (associated with reduced PTH production).…”

“… Iron and creatinine are modifying factors for plasma phosphate concentrations. ( 17 ) Source: Mayo clinic ( https://www.mayocliniclabs.com/testcatalog/Clinical+and+Interpretive/8408 ). …”