Bone density and skeletal metabolism are altered in idiopathic hypercalciuria.
OBJECTIVE
To study bone density in hypercalciuric patients, when classified according to the main metabolic defect.


METHODS
We studied 49 patients, aged 19-60 years with calcium stones and idiopathic hypercalcuria. All subjects underwent an evaluation of mineral metabolism and a spinal and femoral DEXA measurement. Then, patients were classified as having Fasting (FH, 31 subjects) or Absorptive (AH, 18 patients) Hypercalciuria according to a standard oral calcium load.


RESULTS
Spinal bone density was lower only in FH patients as compared to controls (p <0.001). Bone alkaline phosphatase and urine hydroxyproline were higher with respect to controls only in patients with FH (p <0.005 and p <0.015, respectively). After low calcium diet, hydroxyproline excretion continued to be higher in FH patients (p <0.05). Although in the normal range, serum and urine uric acid were higher in hypercalciuric subjects (p <0.03 and p <0.005, respectively); blood pH was lower in hypercalciuric patients than in controls (p <0.01). In FH patients urine hydroxyproline negatively correlated with spinal and femoral density (p <0.001 and p <0.005, respectively), and blood pH positively correlated with spinal density.


CONCLUSIONS
a disordered bone metabolism and bone loss are present only in patients with fasting hypercalciuria. An excessive acid load, possibly of dietary origin, might be involved as a pathogenetic factor.
Giannini
S
S
Institute of Internal Medicine and National Research Council-Centre for Aging Studies of Padova, Italy.
Nobile
M
M
Sartori
L
L
Calò
L
L
Tasca
A
A
Dalle Carbonare
L
L
Ciuffreda
M
M
D'Angelo
A
A
Pagano
F
F
Crepaldi
G
G
D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000209:etiology* / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000652:urine*; D002136:Calcium, Dietary / Q000008:administration & dosage; D016022:Case-Control Studies; D005215:Fasting / Q000378:metabolism; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry / Q000652:urine*; D008297:Male; D008875:Middle Aged
D002136:Calcium, Dietary; D002118:Calcium