Bicarbonate or CO2 tests: functions, procedures and how to read the results

Definition

What is bicarbonate?

The bicarbonate test, also known as the CO2 test, is used to detect electrolyte imbalances or changes in the pH of the blood. This test is part of a series of tests used to analyze the kidneys (renal profile).

The bicarbonate test may be done as part of a routine physical exam or may be recommended if you experience symptoms such as:

• weak
• dizzy
• prolonged vomiting
• difficulty breathing

These symptoms are the result of an electrolyte imbalance, or acidosis, or alkalosis (where acid or base levels are high in body fluids and tissues).

When should I take bicarbonate?

A carbon dioxide or bicarbonate test can look for conditions that affect bicarbonate levels in the blood, including some kidney, lung and metabolic conditions.

This test is often used as a blood test in the laboratory that can help see the cause of the symptoms of the disease.

Precautions & warnings

What should I know before taking bicarbonate?

Several drugs can increase bicarbonate levels such as: fludrocortisone, barbiturates, bicarbonates, hydrocortisone, loop diuretics and steroids. Medicines that can lower bicarbonate levels: methicillin, nitrofurantoin, tetracycline, thiazide diuretics, and triamterene. The doctor will provide an explanation if problems are found. A carbon dioxide (bicarbonate) test can also be done using a blood sample from an artery for an Arterial Blood Gases (ABG) test.

Process

What should I do before taking bicarbonate?

You don't need to make special preparations before the test. Some medications can affect test results.

The doctor will inform you if you need to stop taking the drug before undergoing the test. Do not stop or change medicines until you tell your doctor.

Consult your doctor if you have special concerns about the test, the risks, how the test is performed, and the test results.

How is the bicarbonate process?

The medical personnel in charge of drawing your blood will take the following steps:

• wrap an elastic belt around your upper arm to stop blood flow. This makes the blood vessel under the bundle enlarge making it easier to insert the needle into the vessel
• clean the area to be injected with alcohol
• inject a needle into a vein. More than one needle may be required.
• Insert the tube into the syringe to fill it with blood
• untie the knot from your arm when enough blood is drawn
• sticking gauze or cotton on the injection site, after the injection is complete
• apply pressure to the area and then put a bandage on.

What should I do after taking bicarbonate?

You can do your normal activities after the test. The doctor can order other tests to see the condition in more detail. The test results can be seen after 1 or 2 days.

Explanation of the Test Results

What do my test results mean?

Normal levels are around 23-29 mEq / L.

The normal range may vary in different laboratories. Consult your doctor about your test results.

Bicarbonate levels that are higher or lower than normal levels can indicate that the body is having difficulty maintaining acid and alkaline balance, or that electrolyte balance is disturbed due to lack of or retaining fluids. This may be due to several dysfunctions.

Some of the causes of low bicarbonate levels:

• Addison's disease
• chronic diarrhea
• diabetic ketoacidosis
• metabolic acidosis
• Kidney illness
• ethylene glycol or methanol poisoning
• salicylate (aspirin) overdose

Increased levels of bicarbonate can be caused by:

• severe vomiting
• lung disease, such as COPD
• Cushing's syndrome
• Conn syndrome
• metabolic alkalosis

Some laboratories may use measurements or test different specimens.