Caravaca F, Arrobas M, Pizarro J L, Espárrago J F
Servicio de Nefrología, Hospital Regional Universitario Infanta Cristina, Badajoz, Spain.
Am J Kidney Dis. 1999 May;33(5):892-8. doi: 10.1016/s0272-6386(99)70422-1.
Metabolic acidosis is almost invariably a consequence of advanced renal failure, although its severity can vary widely. To evaluate the determinants of the severity of metabolic acidosis, with special interest in determining if there is any difference in the prevalence and severity of metabolic acidosis between patients with and without diabetes, 113 predialysis patients with renal failure were studied. Criteria for inclusion onto the study were: creatinine clearance (Ccr)/1.73 m2 less than 30 mL/min, no alkali therapy within the previous 30 days, and the absence of respiratory diseases. Forty-eight patients had diabetes (33 patients with diabetic nephropathy). The following data were analyzed: demographics; cause of renal failure; hematocrit; serum urea, creatinine, uric acid, albumin, glucose, hemoglobin A1c, bicarbonate, sodium, potassium, chloride, calcium, phosphorus, and alkaline phosphatase levels; anion gap; urinary protein excretion; Ccr/1.73 m2; half of the sum of creatinine and urea clearances (Ccr-Cu); protein-equivalent nitrogen appearance (PNA); and whether the patients received diuretics (75 patients), angiotensin-converting enzyme inhibitors (54 patients), and/or calcium channel blockers (55 patients). After the exclusion of eight patients because of hypochloremia (three patients with and five patients without diabetes), mean serum bicarbonate levels were significantly greater in patients with diabetes than in the rest of the patients (20.7 +/- 2.3 v 18.2 +/- 2. 3 mmol/L; P = 0.0001). The mean anion gap (mmol/L) was also significantly less in patients with than without diabetes (19.70 +/- 3.65 v 22.35 +/- 3.64; P = 0.003). Eleven of 105 patients had serum bicarbonate levels of 23 mmol/L or greater (9 patients with and 2 patients without diabetes). Pure elevated anion gap followed by mixed (high anion gap and hyperchloremia) were the most common types of metabolic acidosis observed in both groups. There were no differences in PNA, diuretic treatment, or vomiting history between patients with and without diabetes. By multiple logistic regression analysis, the best determinants for a serum bicarbonate level greater than 19 mmol/L were: the diagnosis of diabetic nephropathy (odds ratio, 0.107; P = 0.0002), Ccr-Cu (odds ratio, 0.824; P = 0. 014), and age (odds ratio, 0.966; P = 0.046). In conclusion, patients with diabetes with advanced renal failure showed a less severe metabolic acidosis, which cannot be explained by gastrointestinal hydrogen ion losses, drugs, or reduced protein catabolic rate. Patients with diabetes may have a more efficient extrarenal generation of bicarbonate than end-stage renal failure patients without diabetes.
代谢性酸中毒几乎总是晚期肾衰竭的结果，尽管其严重程度差异很大。为了评估代谢性酸中毒严重程度的决定因素，特别关注确定糖尿病患者和非糖尿病患者之间代谢性酸中毒的患病率和严重程度是否存在差异，对113例肾衰竭透析前患者进行了研究。纳入该研究的标准为：肌酐清除率（Ccr）/1.73 m²低于30 mL/min，前30天内未接受碱治疗，且无呼吸系统疾病。48例患者患有糖尿病（33例患有糖尿病肾病）。分析了以下数据：人口统计学资料；肾衰竭病因；血细胞比容；血清尿素、肌酐、尿酸、白蛋白、葡萄糖、糖化血红蛋白A1c、碳酸氢盐、钠、钾、氯、钙、磷和碱性磷酸酶水平；阴离子间隙；尿蛋白排泄；Ccr/1.73 m²；肌酐和尿素清除率之和的一半（Ccr-Cu）；蛋白当量氮呈现率（PNA）；以及患者是否接受利尿剂治疗（75例患者）、血管紧张素转换酶抑制剂治疗（54例患者）和/或钙通道阻滞剂治疗（55例患者）。在排除8例因低氯血症而被排除的患者（3例患有糖尿病，5例未患糖尿病）后，糖尿病患者的平均血清碳酸氢盐水平显著高于其余患者（20.7±2.3对18.2±2.3 mmol/L；P = 0.0001）。糖尿病患者的平均阴离子间隙（mmol/L）也显著低于非糖尿病患者（19.70±3.65对22.35±3.64；P = 0.003）。105例患者中有11例血清碳酸氢盐水平达到或高于23 mmol/L（9例患有糖尿病，2例未患糖尿病）。单纯性阴离子间隙升高继之以混合型（高阴离子间隙和高氯血症）是两组中最常见的代谢性酸中毒类型。糖尿病患者和非糖尿病患者在PNA、利尿剂治疗或呕吐史方面没有差异。通过多因素逻辑回归分析，血清碳酸氢盐水平大于19 mmol/L的最佳决定因素为：糖尿病肾病诊断（比值比，0.107；P = 0.0002）、Ccr-Cu（比值比，0.824；P = 0.014）和年龄（比值比，0.966；P = 0.046）。总之，晚期肾衰竭的糖尿病患者代谢性酸中毒较轻，这无法用胃肠道氢离子丢失、药物或蛋白质分解代谢率降低来解释。糖尿病患者可能比无糖尿病的终末期肾衰竭患者具有更有效的肾外碳酸氢盐生成能力。
