Low Serum Potassium Concentration Is a Predictor of Chronic Kidney Disease

M. Fukui; M. Tanaka; H. Toda; M. Asano; M. Yamazaki; G. Hasegawa; N. Nakamura

Int J Clin Pract. 2014;68(6):700-704.

Abstract and Introduction

Abstract

Aims The aim of this study was to examine whether low serum potassium concentration could be a predictor of chronic kidney disease (CKD) in a community-based cohort.

Materials and methods We enrolled 1001 subjects, median period of 5.7 years, and evaluated the risk factors for CKD, defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m², and assessed whether low serum potassium concentration could predict CKD.

Results Compared with the subjects without development of CKD, age, body mass index, fasting plasma glucose, uric acid (UA), creatinine and serum sodium concentration were higher, and serum potassium concentration was lower in subjects with development of CKD. Univariate Cox regression analyses demonstrated that age, body mass index, fasting plasma glucose, UA, creatinine, serum sodium concentration and serum potassium concentration were associated with progression of CKD. Multiple Cox regression analysis revealed that age, gender, creatinine and serum potassium concentration were independent predictors of CKD after adjustment for covariates. When serum potassium concentration was below 4.0 mmol/l at baseline, hazard ratio (95% confidence interval) of developing CKD was 2.65 (2.04–3.44; p < 0.0001).

Conclusions Serum potassium concentration could be a clinically relevant risk factor for the progression of CKD, defined as eGFR < 60 ml/min/1.73 m², in healthy subjects.

Introduction

Chronic kidney disease (CKD) is increasingly recognised as a public health problem.^[1] Recent study demonstrated that estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² independently predicts the risk for cardiovascular events and hospitalisation.^[2]

High intake of potassium is protective for cardiovascular disease (CVD).^[3,4] Franse et al.^[5] suggested that the risk of CVD was lower among the patients who had normal serum potassium concentration compared with those who had low serum potassium concentration. Cavusoglu et al.^[6] suggested that serum potassium concentration is independently associated with presence of coronary artery disease. Thus, previous studies have reported the association between potassium and CVD. However, the relationship between serum potassium concentration and the development of CKD remains to be elucidated. The aim of this study was to examine whether low serum potassium concentration could be a predictor of CKD in a community-based cohort.

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Table 1. Baseline characteristics of subjects
	All	Non-CKD	CKD	p
n	1001	738	263
Age (years)	44.6 ± 9.2	42.9 ± 8.6	49.4 ± 9.1	< 0.0001
Gender: Male (%)	452 (45.2)	339 (45.9)	113 (43.0)	0.4061
Smoking (%)	144 (15.5)	112 (12.2)	32 (12.2)	0.2256
Alcohol (%)	297 (29.7)	215 (29.1)	82 (31.2)	0.5329
Body mass index (kg/m²)	21.5 ± 2.6	21.4 ± 2.6	21.8 ± 2.6	0.0154
Systolic blood pressure (mmHg)	109.2 ± 12.6	109.0 ± 12.5	109.9 ± 12.9	0.3497
Diastolic blood pressure (mmHg)	65.3 ± 8.5	65.1 ± 8.4	65.7 ± 8.9	0.3261
Fasting plasma glucose (mmol/l)	4.9 ± 0.4	4.9 ± 0.4	5.0 ± 0.5	0.0266
Total cholesterol (mmol/l)	4.9 ± 0.5	4.9 ± 0.6	4.9 ± 0.5	0.1435
HDL cholesterol (mmol/l)	1.7 ± 0.4	1.7 ± 0.4	1.6 ± 0.4	0.0900
Triglycerides (mmol/l)	0.8 ± 0.3	0.8 ± 0.3	0.9 ± 0.3	0.3275
Uric acid (μmol/l)	279.5 ± 63.9	275.7 ± 65.7	290.3 ± 57.2	0.0015
Creatinine (μmol/l)	69.4 ± 13.5	66.8 ± 12.5	76.6 ± 13.3	< 0.0001
Haemoglobin (g/l)	137.2 ± 15.5	136.6 ± 16.1	139.0 ± 13.7	0.0293
Sodium (mmol/l)	141.9 ± 1.8	141.7 ± 1.8	142.2 ± 1.9	0.0004
Potassium (mmol/l)	4.0 ± 0.3	4.0 ± 0.3	3.8 ± 0.3	< 0.0001
Estimated GFR	75.2 ± 13.5	79.1 ± 12.8	64.3 ± 8.6	< 0.0001

HDL, high-density lipoprotein; CKD, chronic kidney disease; GFR, glomerular filtration rate. Data are expressed as mean ± SD or number (%).

Table 2. Predictors of chronic kidney disease by Cox regression analysis
Variables, unit of increase	Univariate Cox regression analysis		Multiple Cox regression analysis
Variables, unit of increase	HR (95% CI)	p-value	HR (95% CI)	p-value
Age, per 10 years	1.85 (1.63–2.10)	< 0.0001	1.78 (1.52–2.09)	< 0.0001
Gender: Male, yes	0.94 (0.74–1.20)	0.6278	0.11 (0.07–0.18)	< 0.0001
Smoking, yes	0.82 (0.56–1.17)	0.2780	1.23 (0.81–1.81)	0.3245
Alcohol, yes	1.10 (0.84–1.42)	0.4942	1.09 (0.82–1.43)	0.5443
Body mass index, per 1.0 kg/m² increase	1.06 (1.01–1.10)	0.0174	0.99 (0.94–1.05)	0.7347
Systolic blood pressure, per 10 mmHg increase	1.05 (0.95–1.15)	0.3414	1.01 (0.91–1.13)	0.7971
Fasting plasma glucose, per 1.0 mmol/l increase	1.41 (1.06–1.86)	0.0183	1.35 (0.99–1.82)	0.0600
Total cholesterol, per 1.0 mmol/l increase	1.17 (0.93–1.47)	0.1821	0.92 (0.72–1.19)	0.5204
Triglycerides, per 1.0 mmol/l increase	1.18 (0.81–1.71)	0.3778	0.87 (0.54–1.38)	0.5581
Uric acid, per 10.0 μmol/l increase	1.03 (1.01–1.05)	0.0021	1.02 (0.99–1.04)	0.2462
Creatinine, per 10.0 μmol/l increase	1.55 (1.42–1.69)	< 0.0001	2.24 (1.97–2.55)	< 0.0001
Haemoglobin, per 1.0 g/l increase	1.01 (1.00–1.02)	0.0391	1.01 (1.00–1.02)	0.2454
Sodium, 1.0 mmol/l increase	1.15 (1.07–1.22)	< 0.0001	1.02 (0.95–1.10)	0.5252
Potassium, 1.0 mmol/l increase	0.23 (0.15–0.34)	< 0.0001	0.31 (0.21–0.45)	< 0.0001