Bicarbonate levels are almost always done along with other electrolytes to tell your doctor whether your sodium, potassium, chloride, and bicarbonate levels are in balance. They may be measured as part of routine blood testing, or when your doctor suspects an imbalance. Bicarbonate may also be measured when your doctor is evaluating your acid-base balance, to screen for an imbalance, and to monitor a known problem during treatment.

Bicarbonate testing may be requested, usually as part of an electrolyte profile when:

• you are having a routine blood test;
• your doctor suspects that you may be retaining water or are dehydrated, upsetting your electrolyte balance;
• to help evaluate your body's acid-base balance (pH);
• to monitor a condition or treatment that might cause an electrolyte imbalance.

When bicarbonate levels are higher than normal, it suggests that your body is having trouble maintaining its pH balance either by failing to remove carbon dioxide or perhaps because of an electrolyte imbalance, particularly a deficiency of potassium. Both of these imbalances may be due to a wide range of dysfunctions. Bicarbonate elevations may be seen with chronic lung-related problems, such as emphysema, and metabolic problems, such as severe diarrhoea or prolonged vomiting (which can cause metabolic alkalosis - as a consequence of loss of both acid and potassium).

Low bicarbonate levels may be seen with respiratory alkalosis (which can be caused by hyperventilation), metabolic acidosis, shock, starvation, and during kidney failure.

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.