Serum 1,25-Dihydroxyvitamin D Levels in Normal Children and in Vitamin D Disorders

Abstract

\s=b\ Using a precise assay for 1,25-dihydroxyvitamin D in serum, the levels in 103 children, aged 13 months to 16 years, were found to be 43\m=+-\2 pg/mL (mean \m=+-\ SE). This value is higher than reported values in adults and in neonates. Age-related changes in 1,25-dihydroxyvitamin D levels during childhood were also evident. Older children have significantly higher levels than children < 11 years, possibly indicating changes with puberty and the adolescent growth spurt. The values were significantly reduced in childhood uremia (13 \m=+-\5 pg/mL), in hypoparathyroidism (16 \m=+-\1 pg/ml), and in children with Fanconi's syndrome. Treatment with oral calcitriol in these three groups of patients led to increased serum levels.(Am J Dis Child 134: [135][136][137][138][139] 1980) Vitamin D requires two separate hydroxylations, first at carbon 25 occurring in the liver and later at carbon 1 in the kidney, to yield the biologically active metabolite, 1,25-dihydroxyvitamin D (l,25-(OH),D).

Vitamin D Metabolite Levels in Normal Children

“…We, as others (6,17), did not note a significant age-related difference for 24,25(OH)?D3 in general, or when factored for season. We were also unable to show age-related differences for 1,25(OH)?D, as shown by others (4,16). This may have been due to the small number of older children we had in our study, who in previous reports (4,16) have been shown to have higher values of 1,25(OH)?D.…”

“…We were also unable to show age-related differences for 1,25(OH)?D, as shown by others (4,16). This may have been due to the small number of older children we had in our study, who in previous reports (4,16) have been shown to have higher values of 1,25(OH)?D. Aksnes and Aarskog (1) also reported that 1,25(OH),D levels were directly related to pubertal stages.…”

Absence of seasonal fluctuation in serum concentration of 24,25(OH)2-vitamin D in childhood

“…Our study is confined to children, and it is known that 1,25-(OH)~D values vary with age. We found that circulating 1,25(OI-i)2D concentrations are higher in adolescents than in younger children and adults [8,13]. However, we are unable to detect significant differences in serum 24,25(OH)2D values at different ages.…”

“…Using a radioimmunoassay after the HPLC step, they find a value of 52 pg/ml in JanuaryMarch and a value of 76 pg/ml in July-September. These concentrations of 1,25(OH)2D are higher than the mean values usually reported in adults of approximately 28-30 pg/ml using the vitamin Ddeficient chick intestinal receptor assay [8,11,13,17]. Thus other vitamin D metabolites or interfering substances may be measured using this assay.…”

Circadian Rhythms of Blood Minerals during Adolescence

“…The serum concentration of 1,25-(OH)2D, one of the major calcium-regulating hormones, is increased during adolescence (8). We have noted also that 24-h mean PTH concentrations were greater in a group of teenage males compared with adults (20).…”