蓚酸カルシウム結石患者における血中蓚酸濃度について

Abstract

gas chromatograph法で少量の試料で血中蓚酸定量を可能とした.結石(S)群31例, 対照(C)群16例の空腹時蓚酸血中濃度(POA)はそれぞれ1.45±0.39, 1.37±0.39 pg/mlで, 有意差ではない.ホウレン草100 g負荷後のPOAはS群5例では2 h後より, S群5例では4 h後より有意に上昇し, 6 h後のS群は232%, C群は167%と上昇した.S群の2, 4, 6 h値はC群より有意に高かった.ホウレン草負荷後1～2 h尿中排泄量は負荷前に比しS群282%, C群250%と有意に増加し, C群では2 h後に排泄ピークを, S群は4～6 h後あるいはそれ以後にみた.S群4例とC群6例の蓚酸クリアランスは19.0, 18.0 ml/分で, 有意差はなかった.クレアチニンクリアランとの比は両群ともに0.22であった.S群はC群に比し, 蓚酸に対する吸収能力が亢進しているのみでなく, 吸収部位も拡大していると考えられ, 尿中への排泄は遅延していると考えた

A sensitive, simplified method for plasma oxalate determination by gas chromatography is described. After deproteinizing the plasma with 3N HC1 and 20% sulfosalicylic acid, the oxalate was methylated, extracted and analysed by gas chromatography. This method has three advantages i.e., smaller sample size (plasma 5.0 ml), rapidity (takes less than 3 hours) and accuracy. The recovery rate of oxalate added to plasma was 91.42 +/- 11.31% (SD) and the coefficient of variation of replicate determinations was 4.18%. The minimum detectable concentration of oxalate was 0.3 micrograms/ml (oxalate peak was higher than 5 mm). The mean oxalate concentration under fasting conditions from 16 healthy subjects was 1.37 +/- 0.39 micrograms/ml (SD), while that from 31 calcium oxalate stone formers was 1.45 +/- 0.39 micrograms/ml (SD). There was no significant difference in plasma oxalate concentration between the two groups. The dietary influence of oxalate on plasma and urinary oxalate was investigated in 5 healthy subjects and 5 calcium oxalate stone formers. When 100 g spinach (total oxalate 545.5 mg, soluble oxalate 381.5 mg) was given, the increase of plasma oxalate concentration was more prominent in stone formers; in stone formers it increased to 142% of control value at 2 hours (p less than 0.05) after spinach loading, to 163% at 4 hour (p less than 0.01) and to 232% at 6 hours (p less than 0.01); while in healthy subjects increased to 119% at 2 hours (ns) after loading, to 144% at 4 hours (p less than 0.05) and only to 167% at 6 hours (p less than 0.01). Urinary oxalate excretion increased promptly between 1 and 2 hours after loading in both groups, reaching peak levels between 2 and 4 hours after loading in healthy subjects and between 4 and 6 hours or later in stone formers. The mean renal clearance of oxalate was 18.0 ml/min in 6 healthy subjects and 19.0 ml/min in 4 calcium oxalate stone formers. There was no significant difference in oxalate clearance between the two groups. The mean ratio of oxalate/creatinine clearance was 0.22 for stone formers, which was equal to that for healthy subjects.