Serum electrolytes test
Quick answer: An electrolytes test measures sodium, potassium and usually chloride in your blood, which control fluid balance, nerves and muscles. Doctors order it for dehydration, vomiting or diarrhoea, kidney or heart problems, and when you take medicines that affect salt balance.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
- In fertility careElectrolytes may be checked if ovarian hyperstimulation syndrome (OHSS) is suspected after fertility treatment.
How the test is done
- 1You sit and the inside of your elbow is cleaned
- 2A needle draws blood with a short tourniquet time
- 3The sample is sent quickly, as delays can raise potassium
- 4The lab measures sodium, potassium and usually chloride
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A low sodium can be seen with vomiting, diarrhoea, water tablets or drinking too much water, and a high sodium with dehydration. Potassium can be high with kidney problems and some medicines, and low with vomiting, diarrhoea or water tablets.
Who usually has this test
People with vomiting, diarrhoea or dehydration, kidney or heart problems, people on water tablets, and women with ovarian hyperstimulation after IVF.
Risks and aftercare
You can go back to normal activities; tell your doctor about any muscle weakness or palpitations.
Names and options
Also called: electrolytes, sodium potassium test, Na K Cl
Listed by the hospital as
- ELECTROLYTES, SERUM
Questions about this test
Why might electrolytes be checked during IVF?
With ovarian hyperstimulation syndrome, fluid shifts can change sodium and potassium. Your clinic may check electrolytes if you have swelling, pain or vomiting.
Can a delayed sample affect potassium?
Yes. If the sample sits too long or is shaken, red cells can release potassium and give a falsely high result.
What symptoms can abnormal electrolytes cause?
They can cause tiredness, confusion, muscle cramps or weakness, and an irregular heartbeat. Mild changes often cause no symptoms.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
Reception
Waiting area
IVF lab
This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.