Lactated Ringer's solution and risk of hyperkalemia in patients with reduced kidney function

Abstract

Background

Emerging evidence supports the superiority of balanced crystalloids such as Lactated Ringer's (LR) compared to normal saline but concerns for the development of hyperkalemia have limited its use. Although LR inherently contains potassium, there exists a paucity of evidence to suggest that LR could potentiate hyperkalemia. To address this, we evaluated the effect of LR on serum potassium in patients with reduced kidney function who are at risk of developing hyperkalemia.

Methods

We conducted a single-center, retrospective cohort-based observational clinical study that included 293 clinical encounters who were hospitalized with an estimated glomerular filtration rate (eGFR) of < 30 ml/min/1.73m², at the time of hospital admission. Subjects must have received a minimum of 500 ml of LR continuously during the admission. Only those with a minimum of one lab report within 24 hours prior to-, and post-LR administration that reported serum measurements of potassium, glucose, and bicarbonate levels were included. Other potential risk factors for developing hyperkalemia including medication, tube feeds, potassium supplements, and red blood cell transfusion during or within 24 hours after LR administration were recorded.

Results

Serum potassium prior to LR use was highly correlated and predictive of the serum potassium after LR use [P < 0.0001; Odds Ratio 6.77 (3.73 – 12.28)]. Sixteen encounters (5%) developed de-novo hyperkalemia following LR use. No significant positive correlation between the amount of LR administered and the development of hyperkalemia was found.

Conclusions

LR use was not independently associated with the development of hyperkalemia in patients with reduced kidney function.

Introduction

Use of intravenous crystalloid solutions is amongst the most utilized medical therapies worldwide. Numerous studies have investigated their composition and related clinical outcomes.^1,2 In the United States, normal saline (NS) is the most common intravenous crystalloid solution used.³ Administration of large volumes of NS is associated with hyperchloremic metabolic acidosis which can potentially cause renal vasoconstriction leading to impaired kidney perfusion,^4,5 and could also theoretically lead to an increase in serum potassium levels through extracellular shifts.⁶ Crystalloid solutions with electrolyte compositions similar to that of plasma, referred to as balanced crystalloids, including Lactated Ringer's (LR) solution and Plasma-Lyte A, are being increasingly used as an alternative to NS.⁷ Clinical studies involving critically ill patients demonstrate higher rates of acute kidney injury (AKI), need for kidney replacement therapy (KRT) and death with NS use when compared to balanced crystalloids, although, the results have been inconsistent.^8,9 Large randomized clinical trials have shown that balanced crystalloids (with LR being the major formulation used over 90%) resulted in lower rates of mortality, need for new KRT, and persistent kidney dysfunction when compared to NS in critically and non-critically ill adults.^1,2

LR is a physiological, balanced crystalloid solution containing 4 mEq/L of potassium.³ Its use is generally restricted in patients with hyperkalemia and reduced kidney function given potential concerns of exacerbating hyperkalemia.^1,2,10 Our main objective was to assess the effect of LR use on serum potassium levels in patients with reduced kidney function, defined as having an estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73m², a population subset who frequently cannot renally excrete potassium adequately. Our study was prompted by three factors: i) the ubiquitous nature of the clinical question as to whether LR can potentiate hyperkalemia in at risk patients, ii) dearth of currently available data on LR use and its effect on serum potassium levels, and iii) evidence that hyperkalemia is independently associated with a significant mortality and morbidity burden amongst patients with kidney disease.¹¹ Such lack of clinical evidence is clear in clinical trials limiting its use in patients considered at risk of developing hyperkalemia,^1,2 as well as disagreements among clinicians regarding its safety in patients at risk of developing hyperkalemia. This premise was highlighted in a survey we conducted among nephrology clinical faculty and fellows at our institution, prior to data collection, seeking their opinion on whether or not they believed that the administration of LR in patients with reduced kidney function could cause or worsen hyperkalemia. Overall, 22 clinical nephrology faculty members and 10 nephrology fellows took part in this survey. We found that 15 (68%) of the faculty, and 5 (50%) of the fellows believed that LR use could contribute to a significant increase in serum potassium levels in this patient population.

We therefore conducted a novel study evaluating the association between LR use and serum potassium levels in patients with reduced kidney function.