尿路結石再発に関する臨床的検討 (2)高Ca尿症と尿路結右再発について

Abstract

1)尿路結石症例の血中Ca値と入院普通食下および低Ca食下の尿中Ca排泄様式より, 結石症例を1型(正Ca尿症), 2型(いわゆる腸管過吸収型高Ca尿症に相当), 3型(いわゆる腎性高Ca尿症に相当), 4型(いわゆる原発性副甲状腺機能亢進症に相当)の4型に分類した.2)尿路結石97例中1型は77例(79.4%), 2型は9例(9.3%), 3型は8例(8.2%), 4型は3例(3.1%)であった.3)2型, 3型の外来自由食下における尿中Ca排泄は1型のそれにくらべて高値であった.しかし, 1型の中に入院普通食下にくらべ外来自由食下で尿中Ca排泄量が著増する症例が特に男子において26例中6例に認められた.4)1型と2型, 3型で尿中尿酸, 蓚酸, Mg, P排泄量を比較すると, 入院普通食下で1型より2, 3型で尿中尿酸排泄が多い傾向がみられる他は差がなく, 外来自由食下ではすべてに差はみられなかった.5)尿路結石症例を初発で片側性のものと, 初発でも両側性のものまたは再発性のものの2群にわけると, 2型, 3型, 4型では1型よりも両側性または再発性の症例の頻度が若干多いものの有意差はみられなかった.6)以上より, 高Ca尿症が結石形成に際してはたす役割は大きなものではないと考えられたが, 結石再発防止の面からみた場合, 現時点では尿中Ca排泄を減少させる努力が必要であろう

According to the dynamics of the urinary calcium excretion mechanism, we have classified the patients with urolithiasis into 4 groups, namely group I (normocalciuria; urinary calcium excretion of 270 mg/day or less for male patients and 210 mg/day or less for female patients), group II (absorptive hypercalciuria; hypercalciuric with urinary calcium excretion of 200 mg/day or less under the low calcium diet), group III (renal hypercalciuria; hypercalciuric with urinary calcium excretion exceeds 200 mg/day even under a low calcium diet), and group IV (hyperparathyroidism; hypercalciuric patients as in group III with high serum calcium). Of the 97 stone formers, 77 were classified into group I, 9 into group II, 8 into group III and 3 into group IV. Both under the restricted diet and under the ambulatory free diet, urinary calcium excretion of groups II, III and IV was significantly higher than that of the group I patients. It was noteworthy, however, that some of the patients in group I excreted much calcium without restriction of their diet. Although no difference in excretion of oxalate, magnesium and phosphate was observed between the 4 groups, the patients in groups II, and III excreted more uric acid into their urine than group I patients. As for stone recurrence rate, no difference was noted between group I and group II, III or IV. Based on these findings, we conclude that hypercalciuria has no significant role in the stone forming mechanism. However, lowering of urinary calcium and other stone forming constituents is mandatory in preventing stone recurrence until the mechanism of stone formation is elucidated more precisely.