Saudi Journal of Kidney Diseases and Transplantation

: 2010  |  Volume : 21  |  Issue : 3  |  Page : 471--477

Electrocardiographic manifestations of hyperkalemia in hemodialysis patients

Eghlim Nemati1, Saeed Taheri2,  
1 Baqiyatallah Research Center for Gastroenterology and Liver Disease, Tehran; Baqiyatallah University of Medical Sciences, Tehran, Iran
2 Dr. Taheri Medical Research Group, Tehran, Iran

Correspondence Address:
Saeed Taheri
Dr. Taheri Medical Research Group, Tehran


This study was performed to evaluate whether any electrocardiogram (ECG) para­meter can predict the presence of hyperkalemia in patients on maintenance hemodialysis (HD). In January 2006, we conducted a cross-sectional study of 80 stable patients with end-stage renal disease from four university-based HD units of Tehran, Iran, receiving conventional thrice-weekly HD. Pre-HD serum electrolyte values and conventional 12-lead ECG were obtained from each pa­tient. Bivariate linear regression was used for assessing relationship of the study variables with hyperkalemia (K + > 5.2 mg/dL). Multivariable logistic regression was used for evaluating inde­pendent relationship between decreased T wave duration (≤ 170 ms) and other variables. Bivariate correlation analysis showed a significant inverse correlation between serum potassium concentra­tion and T wave duration (P<0.05). None of the patients with serum potassium of ≥ 5.6 mg/dL had T wave duration > 200 ms. Multivariate logistic analysis, after adjustment for other factors, also showed a significant relationship between decreased T wave duration (≤ 170 ms) and hyper­kalemia. We conclude that although hyperkalemia does not induce the usual ECG changes in HD patients, decreased T wave duration was found to be a good indicator of this lethal condition.

How to cite this article:
Nemati E, Taheri S. Electrocardiographic manifestations of hyperkalemia in hemodialysis patients.Saudi J Kidney Dis Transpl 2010;21:471-477

How to cite this URL:
Nemati E, Taheri S. Electrocardiographic manifestations of hyperkalemia in hemodialysis patients. Saudi J Kidney Dis Transpl [serial online] 2010 [cited 2022 Sep 30 ];21:471-477
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Full Text


In patients with renal failure, sudden death is a major reason for mortality and hyperkalemia with cardiac arrhythmia, is one of the main causes. [1],[2] In patients on hemodialysis (HD), hy­perkalemia is known to be a consequence of tissue break down and decreased renal potas­sium excretion. [3] Typical electrocardiographic (ECG) manifestations include peaked T-waves in the precordial leads, and widening of the QRS-complex, both abnormalities of altered cardiac conduction. Flattening or absence of the P-wave, and a "sine-wave" appearance is asso­ciated with severe hyperkalemia. [4]

Despite the critical importance of detecting hyperkalemia quickly, our knowledge about the condition is limited in patients with end-stage renal disease (ESRD). Although, ECG is gene­rally speculated as a reliable rapid method for detection of potentially lethal hyperkalemia, in­vestigators have reported that even in the pre­sence of profound hyperkalemia, there may be only minimal or non-specific ECG changes, or even no changes in HD patients, suggesting that one cannot entirely rely on the ECG features of hyperkalemia in renal failure. [5],[6],[7],[8],[9],[10],[11]

This study was performed to evaluate the pre­sence of expected ECG features in HD patients with hyperkalemia, and to determine whether any of the ECG parameters could predict the existence of hyperkalemia in this population.

 Materials and Methods

The patients were selected from a pool of 111 patients with ESRD receiving HD at four out­patient HD units in Tehran, Iran. Exclusion criteria included:

medically unstable patients;atrial fibrillation;under 18-years of age;less than three months on HD;pregnant women;mentally disabled; andimmeasurable T waves.Verbal consent was taken from all patients. Eighty patients were included in the study. All patients underwent conventional HD for an average of four hours, three times a week. The blood flow rate during HD was 300-350 mL/ min. The dialysate composition was: sodium 140 mEql/L, potassium 2.5 mEq/L, bicarbonate 34 mEq/L, acetate 3.0 mEq/L, chloride 109 mEq/L, calcium 3.0 mEq/L, magnesium 1.0 mEq/L, glu­cose 1 g/L. Patients were categorized into four groups on the basis of their serum potassium concentration (Group-I: 5.2 mg/dL).

The serum albumin, serum potassium, total serum calcium, and serum sodium levels were measured in a blood sample obtained just be­fore a routine dialysis session. Laboratory mea­surements were performed at Baqiyatallah hos­pital's central laboratory without any delay af­ter sample collection; all samples were imme­diately analyzed using standard laboratory tech­niques. Hyperkalemia was defined as a serum K + concentration > 5.2 mg/dL.

A conventional 12-lead ECG was recorded ten minutes before every HD at a paper speed of 25 mm/s for all patients. All ECGs were ob­tained after a five-minute resting period, with the patient lying comfortably in the supine po­sition. For the evaluation of ECG parameters, all ECGs were enlarged twice. Three consecu­tive cardiac cycles were measured and ave­raged. All ECGs were read and analyzed by one investigator without knowledge of patient's laboratory results. ECG parameters' records included P, T and S amplitudes, heart rate, PR interval, ST duration, QRS duration, T dura­tion, and QT interval. Each QT interval and T wave duration were corrected for patient heart rate: QTc = QTint/NRR and Tdc = Tdur/ERR (in milliseconds [ms]). Wave amplitudes and durations were measured from the first deflec­tion to the point of offset regarding the isoelec­tric TP baseline.

Data were expressed as mean ± SD. The se­rum potassium concentration was sorted into quartiles and the relationships of mean diffe­rences between Groups were analyzed using one way ANOVA and Chi-square methods. Post hoc differences between patient-Groups were examined using Tukey's test for multiple comparisons. T-test was used to assess the difference between serum potassium values in patients with T wave duration (ms) ≤ 170 and > 170. P 0.05 was considered significant. The independent association of S wave amplitude, T wave duration, and corrected T wave dura­tion (Tdc) with all other variables were ana­lyzed using multiple linear regression. Multi­ple logistic regression was used for evaluating independent relationship between T wave du­ration and other variables. Variables with a P value 5.2 mg/dL). The pre-HD mean ± SD (range) measurements of these patients were: heart rate 77 ± 14/min (range: 52 - 110); serum albumin 5.5 ± 7.1 mg/dL (2.85 - 6.23), sodium (Na) 138.5 ± 3.9 mg/dL (125 - 146) and serum total calcium (Ca) was 8.9 ± 1.0 mg/dL (6.1 - 11.8). None of these patients had arrhythmia during the study period. The Groups were equivalent in their serum electrolytes concen­tration (P> 0.05). None of the ECG parame­ters showed any significant differences between quartiles of serum potassium concentration (P > 0.05). Details are shown in [Table 1].

However, when we divided the study sub­jects, based on their serum K+ levels into two groups (> 5.2 and ≤ 5.2 mg/dL), significant di­fference in their T wave duration (Tdur) was observed (P= 0.008). Results of multiple linear regression analysis with S wave amplitude as the outcome variable in relation to hyperkalemia lemia is shown in [Table 2].

Multivariate logistic analysis after adjustment for other factors also revealed significant re­lationship between decreased T wave duration (≤ 170 ms) and hyperkalemia (P = 0.009, OR: 5.98, 95% CI: 1.56-22.79). Decreased correc­ted T wave duration (Tdc ≤ 120 ms) was also associated with hyperkalemia [Table 3].

Bivariate correlation analysis found signifi­cant inverse correlations between serum K+ and T wave duration [Figure 1], serum K and corrected T wave duration [Figure 2], and serum Ca concentration and S amplitude [Figure 3].


We found a prevalence of 59% of hyperka­lemia among our HD patients, which is com­parable with other studies. [4] Although we did not observe typical ECG manifestations asso­ciated with hyperkalemia, we found a signifi­cant association between decreased T wave duration (≤ 170 ms) and pre-HD hyperkalemia (> 5.2 mEq/L) in our HD patients. We also found that there was a significant inverse re­lation between serum Ca ++ and S wave ampli­tude with higher calcium concentration related to deeper S waves.

Our findings confirmed that the typical ECG manifestations attributed to hyperkalemia, are rare, especially among severely hyperkalemic HD patients. [5],[6],[7],[8],[9],[10] Despite this, none of the pre­vious studies had investigated all ECG para­meters and their potential relationship with electrolyte disturbances in this population. Aslam et al reported that patients on HD show no specific ECG manifestations in relation with hyperkalemia; however, in that survey the in­vestigators had only assessed the T wave am­plitude and T wave to R wave amplitudes ratio and their association with serum potassium and calcium concentration. [5] In contrast with our findings, they reported an inverse relation bet­ween T wave amplitude and serum calcium concentration, whereas we found a reverse re­lationship between serum calcium value and S wave amplitude [Figure 2]. On the other hand, they also had excluded patients using agents which may counteract cardiac effects of hyper­kalemia. Nevertheless, when we also excluded such subjects, our findings did not change con­siderably and the found associations remained significant as well (data not shown). Szerlip et al also reported two HD patients with profound hyperkalemia (serum K > 9 mg/dL) without any of the expected ECG features. In another case report, Dowod et al [11] reported a HD pa­tient with a serum potassium concentration of 10.3 mg/dL, who had only non-specific ST in­terval and T wave duration changes. [8]

Previous data have suggested that the rate of rise of serum potassium level is more relevant compared to its actual serum concentration. They explained that a slow elevation in serum potassium value, like in ESRD patients, permits compensatory mechanisms to minimize the ef­fects of hyperkalemia. [6] Despite this, the rele­vance of the condition should not be underes­timated. In a case series, Siddiqui et al [12] re­ported three deaths attributed to hyperkalemia in HD patients with serum potassium concen­trations from 7.4 to 8.0. The most important relevance of the problem is when a HD patient comes to the emergency department for any medical problem. Without typical ECG features of hyperkalemia among HD patients, the atten­ding doctors may fail to diagnose; hence the potential life threatening consequences of hy­perkalemia may occur. Therefore, we should consider hyperkalemia as a very critical condi­tion to be aware of, especially in patients with impaired renal function and must educate emer­gency room staff and physicians for the rele­vance and unusual ECG manifestations of hy­perkalemia in HD patients.

Anyhow, although we did not detect "classic" ECG features of hyperkalemia in our HD po­pulation, there was a surprising new relation­ship between decreased T wave duration and the condition. Since, some of our patients with serum potassium concentrations over 5.2 mEq/L had T wave durations longer than 170 ms, one may claim that complete reliance on this ECG feature may lead to loss of some of patients with lethal hyperkalemia; but, on the other hand, none of the subjects with serum potassium > 5.6 had a T wave duration over 200 ms.

In summary, although hyperkalemia does not induce usual ECG changes in all HD patients, it significantly decreases T wave duration. Fur­ther studies with larger study population seem necessary to determine more precise T wave du­ration point in association with hyperkalemia.


This work was supported by grants from Baqiyatallah University of Medical Sciences. The authors would gratefully acknowledge in­valuable assistance of Professor Guy Neild in editing the manuscript.


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