No fasting or any other special preparation is required for this test. However, you must inform your doctor about all the medicines, herbs, or supplements that you might be taking so that the doctor can tell you if any of these need to be stopped before the test to get accurate test results.
Steroids, barbiturates, loop diuretics, hydrocortisone, bicarbonates, fludrocortisone are some medicines that may increase the bicarbonate levels of the blood. Eating acidic foods such as lemons, grapes, plums, etc. may also increase bicarbonate levels.
Tetracycline, triamterene, thiazide diuretics, nitrofurantoin, and methicillin are medications that may lower the bicarbonate levels of the blood.
Do not stop any medication on your own. Instead, consult your doctor for advice.
Avoid eating fruits with a high acid content, like citrus fruits, before undergoing the serum bicarbonate test, as it may give erroneous results.