What is Electrolytes test?

Electrolytes test is a diagnostic test that helps in determining the levels of electrolytes (salts and minerals) in the blood. Our body contains a lot of electrolytes viz sodium, potassium, bicarbonate, calcium, magnesium, phosphate and chloride. 

Electrolytes play different roles in the body, e.g.:

  • Potassium is an essential electrolyte for digestive and bone health. It helps to maintain the functions of muscles, heart and nerves.
  • Sodium helps in maintaining the fluid volume in body. Hyponatremia (lower than normal levels of sodium) is the most common type of electrolyte imbalance and is characterised by confusion, delirium, nausea and headache.
  • Chloride levels are affected by the levels of bicarbonate in body. Excess chloride levels may be observed in case of bicarbonate loss due to some conditions, e.g., diarrhoea.
  • Calcium is vital in maintaining skeletal health, muscle contractions, hormone secretion and blood clotting.
  • Magnesium is involved in neurological functioning and contraction and relaxation of muscles.
  • Phosphorus is important for bones and teeth and about 85% of the total phosphorus in the body is present in bones and teeth.
  • Bicarbonates help in determining the acid-base imbalance in body.

This test is also referred to as the electrolyte panel or “lytes” test.

  1. Why is Electrolytes test performed?
  2. How do you prepare for Electrolytes test?
  3. How is Electrolytes test performed?
  4. Electrolyte test results and normal range

Electrolytes test may be performed as a part of a routine examination or sometimes as a part of a more comprehensive testing procedure. This test is commonly performed in individuals who feel confused, queasy and weak. This test is advised in the following conditions:

Electrolyte test also helps in monitoring the effectiveness of some therapies and determining the side effects of certain medications like diuretics or angiotensin-converting enzyme inhibitors.

Dehydration is a leading cause of electrolyte loss. Therefore, this test is also recommended in individuals who faint and collapse while playing or doing their regular chores and in those hospitalised for heat-related illness.

No special preparation or fasting is needed for this test. However, inform the doctor about any prescription or nonprescription medicine, including herbs, supplements and vitamins taken by the individual as some medications can alter test results. Some medications used for the treatment of high blood pressure or to reduce stomach acids may also affect the results; thus, the doctor should be specifically informed about such medications.

A blood sample is collected by inserting a needle in a vein in an arm. A dressing is applied at the site of venepuncture, and the site is periodically checked for continued bleeding. A urine sample may also be used to determine the levels of electrolytes in body.

The doctor may also recommend a basic urine test, urine test for chloride or blood test for detecting glucose levels along with the electrolyte test.

Various factors like age, medical history, current health status, gender and the method employed for testing affects the results of electrolytes test. This test results may not necessarily indicate the presence of disease. The level of each salt is indicated in electrolyte test result and compared with the normal range based on age and gender of the individual. Results are generally in milliequivalents per litre (mEq/L). The normal range of electrolytes in blood in varying age groups is indicated below:


Different age group

Sodium (mEq/L)

Potassium (mEq/L)

Chloride (mEq/L)

Bicarbonate (mEq/L)






Premature infants




















Adults over age 90





Based on the result and the level of electrolyte imbalance, the doctor will advise the treatment, e.g., reduction in salt intake is advised to individuals with higher levels of sodium and reduction in fluid intake is recommended to individuals with lower levels of sodium.

Normal and abnormal range of electrolytes may also be given in the following manner: 


Serum electrolytes

Normal values

Abnormal values (mmol/L)


135-145 mmol/L

Mild to moderately low: 125-135 mmol/L

Severely low: less than 125 mmol/L

Mild to moderately high: 145-160 mmol/L

Severely high: higher than 160 mmol/L


3.6-5.5 mmol/L

Mild hypokalaemia: less than 3.0-3.4 mmol/L

Moderate hypokalaemia: 2.5-2.9 mmol/L

Severe hypokalaemia: less than 2.5 mmol/L

Mild hyperkalaemia: 5.0-5.5 mmol/L

Moderate hyperkalaemia: 5.5-6.5 mmol/L

Severe hyperkalaemia: 6.5-7.0 mmol/L


8.8-10.7 mg/dL

Hypocalcaemia: less than 8.8 mg/dL

Mild hypercalcemia: more than 10.7 mg/dL

Severe hypercalcemia: more than 11.5 mg/dL


22-26 mg/dL

It increases depending on the acid-base status of the body


1.46-2.68 mg/dL

Hypomagnesemia: less than 1.46 mg/dL

Hypermagnesemia: more than 2.68 mg/dL


3.4-4.5 mg/dL

Hypophosphatemia: less than 2.5 mg/dL

Hyperphosphatemia: more than 4.5 mg/dL


Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.


  1. National Health Service [internet]. UK; Electrolyte test
  2. Shrimanker I, Bhattarai S. Electrolytes. [Updated 2019 May 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan
  3. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Electrolytes
  4. Efstratios Kardalas, Stavroula A Paschou et al. Hypokalemia: a clinical update. Endocr Connect. 2018 Apr; 7(4): R135–R146. Published online 2018 Mar 14. doi: 10.1530/EC-18-0109.
  5. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Electrolytes
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