Servicio Nefrología, Hospital Infanta Cristina, Badajoz, España.
Servicio Nefrología, Hospital Infanta Cristina, Badajoz, España.
Nefrologia (Engl Ed). 2020 Mar-Apr;40(2):152-159. doi: 10.1016/j.nefro.2019.04.011. Epub 2019 Jul 25.
Hyperkalemia (HK) is a common electrolyte disorder in chronic kidney disease (CKD), mainly in the advanced stages. A positive potassium balance due to reduced renal excretory capacity is likely the main pathogenic mechanism of HK. Research into the relative role of each pathogenic element in the development of HK in CKD may help to implement more suitable therapies.
To investigate renal potassium handling in advanced CKD patients, and to determine the differences between patients with or without HK.
Cross-sectional observational study in adult patients with stage 4-5 CKD pre-dialysis. Selection criteria included clinically stable patients and the ability to collect a 24hour urine sample correctly. Blood and urinary biochemical parameters were analysed including sodium and potassium (K). Fractional excretion of K (FEK) and K load relative to glomerular filtration (Ku/GFR) were calculated. HK was defined as a serum K concentration ≥5.5mmol/l.
The study group consisted of 212 patients (mean age 65±14 years, 92 females) with a mean GFR of 15.0±4.2ml/min/1.73m. 63 patients (30%) had HK. Patients with HK had lower mean bicarbonate levels with respect to patients with normal K levels (NK) (20.3±3.1 vs. 22.8±3.2 mEq/l, P<.0001), but no differences were noted in total urinary sodium and K excretion. While mean FEK values were lower in patients with HK (32.1±12.1% vs. 36.4±14.3%, P=.038), Ku/GFR values were significantly greater with respect to the NK subgroup (4.2±1.5 vs. 3.7±1.4 mmol/ml/min, P=0,049). FEK showed a strong linear correlation with Ku/GFR (R=0.74), and partial linear regressions demonstrated that at a similar Ku/GFR level, the FEK of patients with HK was lower than that of NK patients. By multivariate linear and logistic regression analyses, both FEK and Ku/GFR were shown to be the main determinants of K serum levels and HK.
Although the K load relative to glomerular filtration (Ku/GFR) is an important determinant of HK in advanced CKD, the most noteworthy characteristic associated with HK in these patients was the limitation of compensatory urinary K excretion, as indicated by lower FEK.
高钾血症（HK）是慢性肾脏病（CKD）中的一种常见电解质紊乱，主要发生在晚期。由于肾脏排泄能力降低导致的钾正平衡可能是 HK 的主要发病机制。研究 CKD 中每个发病因素在 HK 发展中的相对作用，可能有助于实施更合适的治疗方法。
研究晚期 CKD 患者的肾脏钾处理情况，并确定有或无 HK 的患者之间的差异。
对接受透析前 4-5 期 CKD 的成年患者进行横断面观察性研究。入选标准包括临床稳定的患者和能够正确收集 24 小时尿液样本。分析血液和尿液生化参数，包括钠和钾（K）。计算钾的分数排泄（FEK）和 K 负荷与肾小球滤过率（Ku/GFR）的比值。HK 定义为血清 K 浓度≥5.5mmol/l。
研究组共 212 例患者（平均年龄 65±14 岁，92 例女性），平均 GFR 为 15.0±4.2ml/min/1.73m。63 例（30%）患者有 HK。与血清 K 水平正常（NK）的患者相比，HK 患者的平均碳酸氢盐水平较低（20.3±3.1 vs. 22.8±3.2 mEq/l，P<.0001），但总尿钠和 K 排泄无差异。虽然 HK 患者的平均 FEK 值较低（32.1±12.1% vs. 36.4±14.3%，P=.038），但 Ku/GFR 值明显大于 NK 亚组（4.2±1.5 vs. 3.7±1.4 mmol/ml/min，P=0.049）。FEK 与 Ku/GFR 呈强线性相关（R=0.74），偏线性回归显示在相似的 Ku/GFR 水平下，HK 患者的 FEK 低于 NK 患者。多元线性和逻辑回归分析表明，FEK 和 Ku/GFR 均为血清 K 水平和 HK 的主要决定因素。
尽管肾小球滤过率相关的钾负荷（Ku/GFR）是晚期 CKD 中 HK 的一个重要决定因素，但这些患者中与 HK 相关的最显著特征是代偿性尿钾排泄受限，表现为 FEK 降低。
