Influence of calcium intake on calcitriol levels in idiopathic hypercalciuria in children.
Twenty-four children with idiopathic absorptive hypercalciuria (IAH) and a control group (CG) of 11 healthy children were studied. Plasma 1,25-hydroxyvitamin D3 (calcitriol), parathyroid hormone (PTH), calcium (Ca) and phosphate (P) levels were measured during dietary manipulation. The three diets analyzed were: (A) calcium-restrictive diet (400 mg/1.73 m2/day) for 7 days; (B) supplemented diet (1,000 mg/1.73 m2/day) for 3 days; (C) supplemented diet continued for 15 days. The IAH group had higher levels of serum calcitriol than the control group for all three diets. Serum calcitriol levels in the IAH group decreased in diet B compared to diet A, and returned to levels observed with diet A during diet C. Serum Ca, P and plasma PTH levels did not vary throughout the study in either group. In IAH, two subgroups were observed. In one, serum calcitriol levels were elevated and in the other, serum calcitriol levels were not different from the controls. This second group had a lower P and maximum rate of tubular reabsorption of phosphate per 100 ml of glomerular filtrate than the IAH group with elevated serum calcitriol levels and the control group. These results suggest that IAH in children may be related both to increased serum calcitriol levels and to an altered Tmp/GFR.
Martinez
M E
ME
Division of Biochemistry, La Paz, Hospital, Madrid, Spain.
Villa
E
E
Vazquez Martul
M
M
Sanchez-Cabezudo
M J
MJ
Sanchez
J A
JA
Villa
J R
JR
D000293:Adolescent; D002117:Calcitriol / Q000097:blood*; D002118:Calcium / Q000097:blood / Q000652:urine*; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000493:pharmacokinetics; D002648:Child; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007408:Intestinal Absorption / Q000502:physiology; D007684:Kidney Tubules / Q000378:metabolism; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood
D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D010710:Phosphates; D002117:Calcitriol; D002118:Calcium