ENDOCRINOLOGICAL STUDIES ON PATHOGENESIS ON UROLITHIASIS

III. Calcium Metabolism and Parathyroid Function of Calcium Urolithiasis

Abstract

The calcium metabolism was investigated from electrolyte and endocrinological point of view in 109 male subjects with calcium urolithiasis and 37 normal male subjects without such a history.
1) The urine calcium excretion was higher in stone formers than in control subjects. [173±89mg/day (mean±SD) vs. 134±77mg/day, P<0.01]. Stone formers were classified into two large groups with 288mg/day [mean±2SD of control urinary calcium excretion] as the border line between groups.
2) Urinary cyclic AMP excretion, plasma parathyroid hormone (PTH), and renal tubular reabsorption of phosphate (%TRP) were lower in hypercalciuric stone group than in normocalciuric stone group. These phenomena suggest that the parathyroidal function of the hypercalciuric stone group is suppressed.
3) There was a significant negative correlation of urinary cyclic AMP excretion with urinary calcium excretion in the control group (P<0.01), but not in the normocalciuric stone group. Therefore, we classify normocalciuric stone formers into three groups according to urinary cyclic AMP and urinary calcium excretion for three days. Type I; Increased urinary cyclic AMP is accompanied by decreased urinary calcium. Type II; Increased urinary cyclic AMP is accompanied by increased urinary calcium. Type III; The other patterns between both urinary excretions.. In only Type I of normocalciuric stone group (81 cases), negative correlation could be demonstrated between both urinary excretions (P<0.05). However, in Type II (7 cases), the urinary excretion of cyclic AMP was correlated positively with urinary calcium excretion as hyperparathyroidism (P<0.01).
These reports suggest that there is a clear difference in the mechanism of stone formation between Type I and Type II. In Type I, the change of calcium values may follow one of parathyroidal function, while in Type II, parathyroids may have an initiative in calcium and parathyroidal metabolism, and have a major effect of some sort on urolithiasis and factors such as matrix, which appear to play a major role.
4) There was a strong negative correlation between %TRCa⁺⁺ and urinary calcium excretion in Type I (P<0.001), but some cases of Type II were plotted far from the regression line, and no correlation could be obtained in Type II.
5) Positive correlation could be demonstrated between cyclic AMP content of renal cortex and urinary cyclic AMP excretion, and negative correlation between cyclic AMP content of renal cortex and urinary calcium excretion. Cyclic AMP content was larger in renal cortex than in renal medulla. These results suggest that parathyroid hormone may act on the renal cortex and, therefore, urinary cyclic AMP is supposed to be the second messenger of PTH.
6) Urinary magnesium excretion was significantly higher in hypercalciuria than in normocalciuria (P<0.05). There was a strong positive correlation between the urinary excretion of magnesium and calcium in the stone former group (P<0.01).
Significant correlation could not be found between the urinary cyclic AMP excretion and the electrolytes except for urinary calcium.
7) There was no significant difference between the urinary cyclic AMP of single stone formers and recurrent (and/or multiple) ones. The urinary excretion of calcium was slightly higher in recurrent stone formers than single ones, but this difference was not significant.