Investigative algorithms for disorders affecting plasma potassium: a narrative review

Abstract

Background and Objective: The following article is part of a special series to aid the reader in diagnosing the cause of various electrolyte imbalances. By the end of the article, the reader will be able to order and interpret appropriate investigations when faced with a patient with hyperkalaemia or hypokalaemia. Methods: A narrative, focused literature review was performed using PubMed, OMIM and Google during September 2021 to January 2022 to identify references published from database inception to January 2022; reference lists from these articles were also used. Language was restricted to English. Key Content and Findings: Potassium is an important electrolyte required for neuronal signalling, and its blood concentration is tightly maintained by balancing intake, excretion and distribution throughout the intracellular and extracellular compartment. However, potassium imbalance can occur in many disease states and can lead to significant morbidity and mortality, therefore finding the primary abnormality is important. A laboratory approach to investigate the cause of hyperkalaemia and hypokalaemia is presented. It should be noted that potassium results are particularly susceptible to being falsely low or high in many circumstances, and the validity of potassium results should always be questioned if unexpected before further investigation. Conclusions: Diagnostic flow charts are presented and the limitations of the laboratory tests discussed. The algorithms, by focusing on the approach to the investigation of hyperkalaemia and hypokalaemia, should support healthcare professionals to efficiently and rapidly diagnose most causes of abnormal potassium states.