Serum Bicarbonate

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

Usually as part of a renal profile (collection of tests which help investigate kidney function), to screen for an electrolyte or acid-base imbalance in conditions known to cause such disturbances or to monitor a known imbalance

When this test is required

Bicarbonate testing may be requested, usually as part of an electrolyte profile when: you are having a routine blood test; your doctor suspects that water imbalance is upsetting your electrolyte balance; to help evaluate your acid-base balance (pH); to monitor a condition or treatment that might cause an electrolyte imbalance.

What the Test Detects

When you breathe, you bring oxygen (O2) into your lungs and release carbon dioxide (CO2). Carbon dioxide in your blood is present in three forms: carbonic acid (H2CO3), CO2 dissolved in blood, and bicarbonate (HCO3-), the predominant form. Bicarbonate is a negatively charged ion that is excreted and reabsorbed by your kidneys. Its function is to help maintain the acid-base balance (pH) and to work with sodium, potassium, and chloride to maintain electrical neutrality at the cellular level.Measuring bicarbonate gives an estimation of acid-base balance. This is usually sufficient, but measurements of gasses dissolved in the blood may be done if more information is needed. Bicarbonate may be measured with sodium, potassium, and chloride in an electrolyte profile as it is the balance of these that gives your doctor the most information.See MoreSee Less

Preparation for the Test

None

Sample Requirements

A blood sample taken from a vein in the arm

Additional Notes

Some drugs may increase bicarbonate levels especially diuretics such as frusemide (usually as a consequence of potassium deficiency). Other drugs may cause slightly low levels. Your doctor can advise if this appears to be a problem.

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