✍️ Written by the MedTestBD Editorial Team · Last reviewed: July 2026
What is the Serum Sodium Test?
The serum sodium test measures the level of sodium in your blood. Sodium is an essential electrolyte that helps control fluid balance, nerve function, and muscle activity in the body. It is usually tested as part of an electrolyte panel or kidney function tests. Abnormal sodium levels can be a sign of dehydration, kidney problems, or hormonal disorders.
Why is the Serum Sodium Test Done?
- To investigate symptoms such as confusion, weakness, swelling, or excessive thirst
- To evaluate kidney function, as the kidneys regulate sodium balance
- To monitor patients with heart failure, liver disease, or adrenal disorders
- To check for the effects of diuretic medications (water pills) on electrolyte levels
- Routine part of a metabolic panel during hospital admission or pre-surgery evaluation
- To assess dehydration or fluid overload
Normal Serum Sodium Levels
| Status | Sodium Level (mmol/L) |
|---|---|
| Normal | 136 – 145 mmol/L |
| Low sodium (Hyponatraemia) | Below 136 mmol/L |
| High sodium (Hypernatraemia) | Above 145 mmol/L |
Low sodium can cause nausea, headache, confusion, and in severe cases, seizures. High sodium is usually linked to dehydration. Both conditions require medical assessment to identify the underlying cause.
How to Prepare for the Serum Sodium Test
- No fasting is required for this test
- Stay well hydrated unless your doctor has advised fluid restriction
- Inform your doctor about all medications you take — especially diuretics, corticosteroids, or blood pressure medicines, as these directly affect sodium levels
- A simple blood sample is drawn from a vein in your arm
Serum Sodium Test Price in Bangladesh
Serum sodium test prices vary between diagnostic centers across Bangladesh. Compare serum sodium test prices on MedTestBD →
⚠️ This information is for general reference only. Always consult a qualified physician before undergoing any medical test.
