Surreal illustration balancing sodium levels and surgical tools for optimal health.

Decoding Sodium Levels: What Your Blood Test Really Means for Surgical Outcomes

Theo Raines in Health & Wellness July 2025 • 4 min read.

"Preoperative sodium imbalances can significantly impact your health during and after surgery. Learn how to interpret your sodium levels and what you can do to optimize your surgical outcomes."

Before undergoing surgery, patients often have a series of blood tests, including a measurement of sodium levels. Sodium is vital for maintaining fluid balance, nerve function, and muscle contractions. When sodium levels are outside the normal range, it's known as dysnatremia, which can impact surgical outcomes.

Recent research has highlighted the importance of preoperative sodium levels in predicting postoperative mortality. A study from South Africa sheds light on how both high and low sodium levels can affect patient outcomes after surgery, emphasizing the need for careful monitoring and management.

This article breaks down the key findings of this study, explaining what preoperative sodium measurements mean for surgical patients. We will explore the implications of hypernatremia (high sodium) and hyponatremia (low sodium), and what steps you can take to ensure your sodium levels are optimized before surgery.

Why Do Sodium Levels Matter Before Surgery?

Surreal illustration balancing sodium levels and surgical tools for optimal health.

Sodium plays a crucial role in various bodily functions, including fluid balance, nerve transmission, and muscle function. Normal sodium levels are essential for maintaining overall health, and any imbalances can lead to significant complications, especially during and after surgery. Dysnatremia, or abnormal sodium levels, can disrupt these critical functions and increase the risk of adverse outcomes.

The South African Surgical Outcomes Study (SASOS) revealed a significant association between preoperative sodium levels and postoperative mortality. The study, which included data from 3,927 patients across 45 government hospitals in South Africa, found that patients with hypernatremia had a significantly higher risk of mortality after surgery. While hyponatremia did not show the same independent association in this particular study, the overall importance of balanced sodium levels cannot be overstated.

Fluid Balance: Sodium helps regulate the amount of water in your cells and blood, which is critical for maintaining blood pressure and preventing dehydration or fluid overload.
Nerve and Muscle Function: Sodium ions are essential for transmitting nerve impulses and enabling muscle contractions. Imbalances can lead to muscle weakness, cramps, or even neurological issues.
Overall Health: Maintaining proper sodium levels supports kidney function, blood pressure regulation, and overall cellular health.

Understanding these roles helps explain why preoperative sodium levels are closely monitored. By identifying and addressing any imbalances before surgery, healthcare providers can minimize potential risks and improve patient outcomes. The SASOS study underscores the necessity of this vigilance, particularly in diverse patient populations.

Taking Control of Your Health Before Surgery

Understanding the role of sodium and its impact on surgical outcomes empowers you to take proactive steps in managing your health. By working closely with your healthcare team, monitoring your sodium levels, and addressing any imbalances before surgery, you can contribute to a safer and more successful surgical experience.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.7196/samj.2018.v108i10.13178, Alternate LINK

Title: Preoperative Serum Sodium Measurements And Postoperative Inpatient Mortality: A Case-Control Analysis Of Data From The South African Surgical Outcomes Study

Subject: General Medicine

Journal: South African Medical Journal

Publisher: South African Medical Association NPC

Authors: M Ramburuth, Y Moodley, P D Gopalan

Published: 2018-10-02

Everything You Need To Know

Why is measuring sodium levels important before I have surgery?

Measuring sodium levels before surgery is important because sodium plays a crucial role in maintaining fluid balance, nerve function, and muscle contractions. Abnormal sodium levels, known as dysnatremia, can disrupt these critical functions and increase the risk of adverse outcomes during and after surgery. Identifying and addressing any imbalances, such as hypernatremia (high sodium) or hyponatremia (low sodium), before surgery can help minimize potential risks and improve patient outcomes, as highlighted by the South African Surgical Outcomes Study (SASOS).

What does the South African Surgical Outcomes Study (SASOS) tell us about sodium levels and surgery?

The South African Surgical Outcomes Study (SASOS) revealed a significant association between preoperative sodium levels and postoperative mortality. Specifically, the study found that patients with hypernatremia had a significantly higher risk of mortality after surgery. While hyponatremia did not show the same independent association in this particular study, the overall importance of balanced sodium levels cannot be overstated. This underscores the necessity of vigilance in monitoring sodium levels, particularly in diverse patient populations.

What are the specific functions of sodium in my body that make it so important before surgery?

Sodium is vital for several key bodily functions. First, it helps regulate fluid balance by controlling the amount of water in your cells and blood, which is critical for maintaining blood pressure and preventing dehydration or fluid overload. Second, sodium ions are essential for transmitting nerve impulses and enabling muscle contractions, with imbalances potentially leading to muscle weakness, cramps, or even neurological issues. Third, maintaining proper sodium levels supports kidney function, blood pressure regulation, and overall cellular health. These roles explain why preoperative sodium levels are closely monitored.

What are the potential complications if I have hypernatremia before undergoing a surgical procedure, based on the information available?

According to the South African Surgical Outcomes Study (SASOS), hypernatremia (high sodium levels) before surgery is associated with a significantly higher risk of postoperative mortality. While the specifics of why hypernatremia leads to this increased risk aren't detailed here, it is likely linked to disruptions in fluid balance, nerve function, and muscle contractions, potentially exacerbating complications during and after surgery. Addressing hypernatremia before surgery is vital to mitigating these risks.

If low sodium levels (hyponatremia) weren't directly linked to higher mortality in the South African Surgical Outcomes Study (SASOS), why should I still be concerned about it before surgery?

While hyponatremia (low sodium levels) did not show the same independent association with increased mortality as hypernatremia in the South African Surgical Outcomes Study (SASOS), it remains a concern before surgery because balanced sodium levels are critical for overall health. Hyponatremia can still disrupt essential bodily functions such as fluid balance, nerve transmission, and muscle function. These disruptions can lead to complications that, while not directly increasing mortality risk in the SASOS study, can still negatively impact surgical outcomes and recovery. Therefore, addressing hyponatremia before surgery helps ensure optimal physiological conditions.