Yanamandra Uday, Chauhan Pooja, Lad Deepesh, Khadwal Alka, Prakash Gaurav, Varma Subhash, Malhotra Pankaj
Clinical Hematology Division, Department of Internal Medicine, PGIMER, Chandigarh, 160012 India.
Indian J Hematol Blood Transfus. 2017 Jun;33(2):188-194. doi: 10.1007/s12288-016-0711-x. Epub 2016 Aug 6.
High dose methotrexate (Mtx) therapy is commonly used in hemato-oncological practice. Alkalization of urine is a part of high dose methotrexate therapy for preventing crystallization in urine to avert renal insufficiency. Alkalization is monitored by urine pH at regular intervals. Oral pH has occasionally been used as a surrogate for oral mucositis. To compare and correlate pH of various body secretions (venous blood, oral salivary, lacrimal and urine) among patients undergoing alkalization with intravenous sodium bicarbonate during high dose methotrexate therapy. A prospective single center study in patients with hematological malignancies receiving Mtx > 1.5 g/m over 4-24 h. Patients were assessed for pH (from all 4 body fluids) at regular time intervals (q8 h) starting 6 h-prior and 48 h-post initiation of Mtx therapy. Mean pH of urine/oral was compared to surrogate samples. The mean oral pH was 6.9 (SD 0.65), the mean urinary pH was 7.59 (SD 0.773) the mean pH by venous blood gas analysis (venous pH) was 7.388 (SD 0.059), the mean lacrimal pH was 7.4536 (SD 0.527). Repeated measures ANOVA suggests that pH of different body fluids differ and cannot be used interchangeably [F (2.417, 309.361) = 54.89, < 0.0005]. There was no statistically significant correlation between any other pair of assessed body fluids. On paired t test only the means of venous pH and urinary pH did not differ statistically ( 0.056). Venous pH significantly correlated with urinary pH but the strength of correlation was weak (r 0.184; 0.037). pH of different body fluids is statistically different even when sampled simultaneously thus the pH of one fluid cannot be substituted for other. Based on this study we cannot substitute urinary pH with any other body fluids presently in patients undergoing high dose methotrexate and alkalization except in rare circumstances when venous pH can be used as a poor surrogate for urinary pH in situations where urinary pH cannot be monitored due to any reason. There was no surrogate for oral pH among the studied body fluids.
高剂量甲氨蝶呤（Mtx）疗法在血液肿瘤学实践中常用。尿液碱化是高剂量甲氨蝶呤疗法的一部分，用于防止尿液中结晶形成以避免肾功能不全。通过定期监测尿液pH来监测碱化情况。口腔pH偶尔被用作口腔黏膜炎的替代指标。比较并关联在高剂量甲氨蝶呤治疗期间接受静脉注射碳酸氢钠碱化的患者不同身体分泌物（静脉血、口腔唾液、泪液和尿液）的pH。对接受超过4 - 24小时Mtx剂量>1.5 g/m²的血液系统恶性肿瘤患者进行前瞻性单中心研究。在Mtx治疗开始前6小时至治疗后48小时，定期（每8小时）评估患者所有4种体液的pH。比较尿液/口腔的平均pH与替代样本。口腔平均pH为6.9（标准差0.65），尿液平均pH为7.59（标准差0.773），静脉血气分析的平均pH（静脉pH）为7.388（标准差0.059），泪液平均pH为7.4536（标准差0.527）。重复测量方差分析表明不同体液的pH不同，不能相互替代使用[F（2.417, 309.361）= 54.89，P < 0.0005]。所评估的其他任何一对体液之间均无统计学显著相关性。配对t检验显示只有静脉pH和尿液pH的均值在统计学上无差异（P = 0.056）。静脉pH与尿液pH显著相关，但相关性强度较弱（r = 0.184；P = 0.037）。即使同时采样，不同体液的pH在统计学上也不同，因此一种体液的pH不能替代另一种。基于本研究，目前在接受高剂量甲氨蝶呤和碱化治疗的患者中，除了在因任何原因无法监测尿液pH的罕见情况下静脉pH可作为尿液pH的不良替代指标外，我们不能用任何其他体液替代尿液pH。在所研究的体液中没有口腔pH的替代指标。
