Evidence for metabolic origin of absorptive hypercalciuria Type II.
The objective of this retrospective data analysis was to test the hypothesis that absorptive hypercalciuria Type II (AH-II) is a less severe variant of absorptive hypercalciuria Type I (AH-I), a common cause of calcareous stones. 24-h urinary calcium obtained on constant metabolic diets was retrieved from several data sources, including those of the authors and another group. On a low calcium diet (10 mmol calcium), 35 patients with AH-II were compared with 70 non-stone formers (NSF) and 76 patients with AH-I. On a high calcium diet (25 mmol calcium/day), 10 patients with AH-II were compared with 35 NSF and 32 with AH-I. On a low calcium diet for all participants, 24-h urinary calcium in AH-II (4.13 ± 0.63 mmol/day) was significantly higher than in NSF (3.06 ± 1.17 mmol/day), but significantly lower than in AH-I (6.11 ± 1.14 mmol/day) (p < 0.001). In a smaller subset, fractional intestinal calcium absorption in AH-II (65.0 ± 11.1%) was intermediate between NSF (50.0 ± 6.4%) and AH-I (71.0 ± 6.7%) (p < 0.001 between AH-II and other groups). On a high calcium diet, the rise in urinary calcium in AH-II was significantly higher than in NSF, but not as marked as in AH-I. Estimated calcium balance in AH-II was similar to NSF, but significantly more positive than AH-I. In conclusion, AH-II shares with AH-I the same metabolic disturbance(s) stimulating intestinal absorption and renal excretion of calcium but to a lesser degree. Bone might be spared in AH-II.
Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8885, USA. Charles.Pak@UTSouthwestern.edu
Charles Y C
CY
Pak
Margaret S
MS
Pearle
Khashayar
K
Sakhaee
D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D053565:Hypercalciuria / Q000145:classification* / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*; D007408:Intestinal Absorption; D008297:Male; D012189:Retrospective Studies; D013577:Syndrome
D002136:Calcium, Dietary