Sodium (Na+) [Serum/Urine]

Clinical definition of the sodium test
Sodium is an electrolyte that works with other electrolytes, such as potassium, chloride and bicarbonate (total CO2) to help maintain and regulate the amount of fluid (water and electrolyte) balance in the body, stimulate muscle contraction and maintain a stable acid-base balance in blood and tissue cells. The passage of sodium in and out of cells is also very necessary for many body functions, such as transmitting electrical signals in the brain and in the muscles.

Why is the sodium test done?
This test measures the concentration of sodium in the blood. It may be done in the following cases:-

  • As a routine medical exam as part of an electrolyte or metabolic panel
  • To help evaluate water and electrolyte imbalance and kidney function
  • At regular intervals to check for the effect of a medication for electrolyte imbalance
  • To check if sodium concentration is within normal limits and to help evaluate electrolyte balance to monitor chronic or acute hypernatremia or hyponatremia
  • To monitor certain chronic conditions, like high or low blood pressure
  • To find the cause of symptoms from low or high levels of sodium
  • Check the progress of diseases of the kidneys or adrenal glands
  • To check sodium imbalance or disorders associated with abnormal sodium levels

What are the common signs/symptoms when the sodium test is done?

  • Turgor of the skin 
  • Swelling in the ankles, feet, and legs
  • Severe dehydration 
  • Edema
  • Confusion
  • Weakness
  • Lethargy
  • Seizures at times

Who should do the sodium test (Target population)?
Persons showing the above signs & symptoms or those having an electrolyte imbalance and may be on a medication for it.

What should I do before the sodium test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test


(Blood Sample)





Venipuncture - Collection of blood from a vein, usually from the arm.

Random Mid-Stream Urine Sample (not at the beginning and not at the end) should be collected. Care must be taken to clean the genitals well before collection.

Follow these steps to get the sample

Initial or the first few drops of the urine should be discarded in the toilet.

Mid-stream urine sample should be collected in the sterile container provided.

Latter part or the end of the urine should not be collected.

Cap the container. Keep it in the refrigerator or a cool place during the collection period.


No Fasting Required.

No other special preparations required.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my sodium test results?

Reference Range*

Normal range* (mmol/L)



136 to 145


136 to 145

0 - 7 days 

131 - 144

7 - 31 days 

132 - 142

1 - 6 months 

132 - 140

6 months - 1 yr

131 - 140

> 1 yr

132 - 141




40 to 220


40 to 220




6-10 years

41 to 115

20 to 69

10-14 years

63 to 177

48 to 168

24 hrs Urine

75-200 meq/day

‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the sodium test

  • Diabetes insipidus
  • Hyperaldosteronism
  • Cushing syndrome
  • Congestive heart failure
  • Nephrotic syndrome
  • Acute adrenal crisis
  • Diabetic hyperglycemic hyperosmolar coma
  • Drug-induced hypothyroidism
  • Hepatorenal syndrome
  • Hypopituitarism

Other tests related to the sodium test

  • Chloride
  • Bicarbonate (or total CO2)
  • Potassium
  • Electrolyte panel
  • Aldosterone
  • Osmolality
  • Comprehensive Metabolic Panel (CMP)
  • Basic Metabolic Panel (BMP)
  • Anti-Diuretic Hormone

Book This Test
Sodium (Serum)