3.17b_05 Assessing a Patient with an Electrolyte Imbalance

Assessing a Patient with an Electrolyte Imbalance
Session Overview
Description
This session explores the common and important causes of electrolyte imbalances commonly seen in primary care, particularly socdium and potassium, and presents a set of typical case studies of patients who have electrolyte disturbances.

This session was reviewed by Khyati Bakhai and last updated in February 2020.

Learning Objectives
By the end of this session you will be able to:

• Identify common causes of electrolyte imbalances commonly seen in primary care
• Use a systematic approach to the assessment of common electrolyte imbalances
• Use a systematic approach to the investigation of electrolyte imbalances in primary care
• Recognise rare but serious electrolyte imbalances that may present in primary care and take appropriate prompt action

This session considers abnormalities of the commonly measured electrolytes sodium and potassium.

These electrolytes are intimately linked to renal function, and to interpret abnormalities, doctors must understand the homeostatic mechanisms used by the body to maintain equilibrium in health and compensate for changes in disease.

As an extracellular ion, sodium concentrations reflect not just body sodium content, but the degree of dilution in serum. Therefore, high or low serum sodium concentrations often do not reflect high and low body sodium content respectively.

Conversely, as a predominantly intracellular ion, potassium concentrations in serum vary primarily as a result of either redistribution (e.g. as a result of acid-base changes), or whole body potassium status. The magnitude of whole body potassium deficit is much greater than serum values might suggest because the ion is mostly intracellular.