Bicarbonate Test

Bicarbonate (or HCO3) is an electrolyte present in the human body that helps keep the acid-base balance in check. It is transported by the blood to the lungs, from where it gets expelled as carbon dioxide (CO2). Kidneys also play a role in bicarbonate regulation by absorbing and removing bicarbonate.

A bicarbonate test helps measure the total CO2 in the blood, which is present in the form of bicarbonate. The bicarbonate (or total CO2) test is generally not done selectively. It is ordered along with sodium, potassium and chloride tests as a part of an electrolyte panel, which is included in a basic metabolic panel. Bicarbonate level might also be calculated as a part of a blood gas panel.

A bicarbonate test is prescribed to monitor the acid-base balance of the body. A doctor may prescribe this test if a patient has a renal illness, liver failure or other metabolic problems. Chronic Kidney Disease (CKD) is a serious problem in India. The levels of bicarbonate play an essential role in the matter of renal diseases. Therefore, this test is routinely prescribed in this condition.

The test uses only the plasma, that is, the fluid in your blood, excluding the cells in the blood and platelets that help blood clot. The amount of bicarbonate is then measured by how fast the sample's acidity changes.

Metabolic acidosis, Metabolic alkalosis (both of these disorders denote an imbalance in the level of electrolytes in the body)

A bicarbonate test and blood gas panel are ordered to evaluate the severity of the pH imbalance when a doctor finds symptoms of acidosis or alkalosis is suspected.

 A bicarbonate test help experts determine whether the condition of the patient is primarily due to one of the two reasons:

• A respiratory disorder (imbalance between the amount of oxygen being inhaled and CO2 being exhaled).
• A metabolic disorder (imbalance in the acid produced in the body or inability of the kidneys to excrete acid from the body).

The test also helps in the formulation of a treatment plan so that the acid-base balance is restored.

This test may also be ordered when you have an acute condition with symptoms such as:

• Extreme vomiting and/or diarrhoea
• Weakness and fatigue
• Difficulty in breathing (respiratory distress)
• Dehydration
• Confusion
• Feeling feverish
• Dyspnoea or shortness of breath
• A rapid heart rate
• Swelling or bloating of various parts of the body
• Fatigue or tiredness
• Numbness in the hands or feet
• A tingling sensation in the body
• Muscle weakness
• Constant irritability
• Spasms or cramping of the muscles
• Seizures

Some disease conditions for which a Bicarbonate Test can be prescribed are:

• Addison’s disease
• Diabetic ketoacidosis
• Chronic diarrhoea
• Metabolic acidosis
• Metabolic alkalosis
• Respiratory alkalosis
• Renal disease
• Shock
• Aspirin overdose
• Lung diseases
• Cushing’s disease
• Methanol poisoning

An electrolyte panel can be used to help diagnose electrolyte imbalances and acid-base (pH) imbalances, that is, metabolic acidosis or metabolic alkalosis. These tests may be done as a part of a routine health check-up or to help evaluate and monitor a number of chronic or acute illnesses, such as:

• Kidney disease
• Liver disease
• Lung disorders
• High blood pressure (hypertension)

Electrolyte panels may be ordered at regular intervals or when you have a disorder or condition or if you have currently been put on a medication that may cause an electrolyte imbalance.

Before the Test

Usually you don't need specific preparation for a bicarbonate test. However, if your doctor has recommended other tests that require specific preparation, your doctor may advise you to fast for a few hours. It's best to consult your doctor before any test for guidance specific to your needs.

During the Test

During the bicarbonate test, a small amount of blood will be taken from a vein in your arm. Here's what you can expect:

• An antiseptic solution will be used to thoroughly cleanse the puncture site.
• A tourniquet will be placed around your arm tightly to make the veins more visible.
• A needle will be gently inserted into the vein selected for the test for drawing blood. It may cause a pinching sensation for a few seconds.
• The collected blood will be placed into a vial or small tube, labeled with your information.

After the Test

Consequent to the blood draw, expect the following:

• A bandage will be applied to the puncture site to prevent further bleeding.
• Slight bruising is common, but feeling dizzy is not. In that case, sit down for a few minutes.
• In case of bleeding, pain, or a rash at the needle site, please contact your doctor promptly.

The Bicarbonate test includes the following parameters - Measuring the concentration of bicarbonate in the blood.

An electrolyte panel usually covers these parameters. It measures the bicarbonate levels as well as the sodium, potassium, chloride levels in your blood.

There may be an imbalance of all these elements in the body, which is indicated by the following symptoms.

Following a diagnosis, once the treatment for metabolic acidosis or metabolic alkalosis is initiated by a healthcare provider or doctor, the bicarbonate test may be prescribed every six months to monitor and regulate the dosage. The results of the electrolyte panel may help your doctor to continue the same treatment or modify the dosage of ongoing medicines.

The bicarbonate test is applicable for males and females, both adults and children.

The normal values and reference ranges of the test may vary from lab to lab. Please refer to the ranges mentioned in the report and consult a doctor to understand the interpretation of lab reports.

Changes in the levels of bicarbonate and carbon dioxide dissolved in the blood are an indicator of the acid-base imbalance in the body. The nature of the imbalance, however, cannot be determined solely from the bicarbonate test value itself and the test for the determination of bicarbonate is rarely ordered alone.

A bicarbonate test value is significant only along with the value of other electrolytes in a whole electrolyte panel and all the other electrolytes are assessed along with it in order to do screening for electrolyte imbalance.