Bicarbonate (C02)

July 21, 2020

What is Bicarbonate (C02)?

Bicarbonate is a byproduct of the body’s metabolism. It is a negatively charged ion which helps to maintain the acid-base balance (pH) of the body.[1] Bicarbonate is also an electrolyte alongside sodium, potassium and chloride. Electrolytes conduct electrical impulses in the body. It is essential the electrolytes in the body are balanced to make sure our cells and organs function normally.

Why take a Bicarbonate blood test?

Taking a bicarbonate blood test gives an estimation of acid-base balance. Bicarbonate is an important component in the physiological pH buffering system in the human body. Carbon dioxide is a waste of product of cellular respiration, so is removed from the body when we exhale and up to 75% of the carbon dioxide into the body is converted to carbonic acid. Carbonic acid is quickly turned to bicarbonate which is an alkali and keeps the acid-base balance of the body stable.

A fluctuation in bicarbonate levels, either higher or lower than normal, usually suggest the body is finding it difficult to maintain the acid-base balance. Either an electrolyte imbalance or a failure to remove carbon dioxide is often the reason for this.[2]

A check on your bicarbonate levels is included in Forth’s Ultimate health check.  This blood test analyses almost 50 biomarkers integral to good health.

What function does Bicarbonate have in the body?

Bicarbonate, water, hydrogen, haemoglobin, phosphate and carbon dioxide makes up the buffering system in the human body. If pH levels are detected in the human body, then the buffering system needs to react quickly to restore it back to normal. If bicarbonate levels increase or decrease too much then this suggests the body is struggling to maintain its acid-base buffering system.

How do changes in Bicarbonate affect health and wellbeing?

The causes of increased or decreased bicarbonate levels can make you feel generally unwell. For example, severe vomiting can cause a rise in bicarbonate levels and can lead to dehydration. Therefore, it’s not necessarily the change in bicarbonate levels which affects your health and wellbeing but the underlying cause.

If you are worried about your bicarbonate level or just want to check where you fall on the range, you can test your level with a simple at-home blood test.

​What can cause Bicarbonate to change?

Increased bicarbonate levels can be caused by:

  • Metabolic alkalosis
  • Severe vomiting
  • Hormone disorders such as Cushing’s syndrome
  • Lung diseases such as emphysema and chronic obstructive pulmonary disease (COPD)

Low bicarbonate levels are caused by:

  • Metabolic acidosis
  • A hormone disorder such as Addison’s disease
  • Diabetic ketoacidosis
  • Chronic diarrhoea
  • Kidney disease
  • Alcohol poisoning
  • Aspirin overdose

What are the most common symptoms?

Common symptoms of metabolic alkalosis are:

  • Severe and prolonged vomiting
  • Severe dehydration
  • Increased urine production and output

Although symptoms of metabolic acidosis are not specific, some symptoms are:

  • Chest pain
  • Headaches
  • Palpitations
  • Muscle weakness
  • Nausea
  • Weight gain
  • Altered appetite

Depending on the overall cause of the altered bicarbonate levels, a lack of energy, lethargy and changes in mood may also be experienced.

How to keep Bicarbonate in the healthy range

It is essential that we keep electrolytes and fluid intake balanced. Electrolytes ensure our cells can communicate with each other by enabling electrical impulses to be passed between them. It is common to drain our electrolyte store during intense exercise through sweat or during periods of illness such as diarrhoea and vomiting. Rehydration therapy can help to restore electrolyte levels after an illness which are readily available from local pharmacies and supermarkets. These contain important electrolytes whilst also restoring fluid loss, too.

Keeping hydrated is always important. Try taking small sips of water throughout the day rather than huge gulps when you are thirsty. If you are participating in high-intensity exercise over a prolonged period, you may need to consider consuming a sports drink to help with your electrolyte balance as well as staying hydrated with ordinary water. Remember the body loses water every time it urinates, sweats and cries so it’s essential to stay topped up with water.

Smoking is a major risk factor for the development of COPD. COPD not only affects general health but negatively impacts the quality of life, too.[3] Lung disease including COPD can cause increased bicarbonate levels. Therefore, giving up smoking will help the body to maintain its acid-base balance.


[1] Hamm, L, L., Nakhoul, N and Herring-Smith, K, S. (2015). Acid-Base Homeostasis. Clin J Am Soc Nephrol: 10(12), pp 223-2242

[2] Lab Tests Online. (2017). Bicarbonate. Available at:

[3] Riesco, J, A et al. (2017). Active Smoking and COPD Phenotype: Distribution and Impact on Prognostic Factors. International Journal of COPD: 12, pp 1989-1999.

View full list of biomarkers

This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.