What is bicarbonate?
Bicarbonate is an important part of the so-called bicarbonate buffer, the most important buffer system in the body. It ensures that the pH value in the body remains constant and that strong fluctuations can be quickly balanced out. As a base, bicarbonate is responsible for balancing acidic substances.
Environment too acidic
If acidic substances accumulate as protons (H+), the bicarbonate (HCO3) absorbs them and ultimately forms water (H2O) and the slightly acidic carbon dioxide (CO2) via an intermediate step as carbonic acid (H2CO3). CO2 is exhaled from the blood via the lungs so that the pH value can normalize.
Environment too alkaline
If too many bases form in the body, the bicarbonate buffer also intervenes. In this case, less CO2 is exhaled and instead is converted back into bicarbonate and acidic substances. The pH value drops.
When is bicarbonate determined?
As bicarbonate is an essential building block in the bicarbonate buffer, it is measured in all diseases that could lead to a change in the pH value. As a rule, these are respiratory or metabolic diseases. It is also used in the liver in the production of urea, so diseases of this organ reduce bicarbonate consumption. The following causes can therefore be hidden behind altered bicarbonate levels:
- Diseases and functional disorders of the kidney
- Diseases and functional disorders of the liver
- Severe circulatory disorders
- Metabolic disorders such as diabetes mellitus
Bicarbonate levels
To determine the bicarbonate level, the doctor usually takes a small blood sample from an artery. The following normal values apply:
|
Standard bicarbonate (HCO3) |
22 – 26 mmol/l |
The values must always be assessed in conjunction with the reference values of the respective laboratory, which is why deviations are possible. Age also plays a role in the assessment of the measured value. Newborn babies in particular have a lower bicarbonate.
When is the bicarbonate too low?
Bicarbonate is low when the body is trying to buffer a so-called metabolic acidosis. This occurs when the pH value is too low and the blood is therefore too acidic (acidotic). As a counter-reaction, a lot of bicarbonate is consumed and CO2 is increasingly exhaled via the lungs. This can be the case, for example, in a metabolic derailment caused by diabetes mellitus. However, there are also other possible causes of metabolic acidosis, such as abnormal bicarbonate production in the pancreas or a high lactate concentration during heavy muscle work.
When is the bicarbonate too high?
What to do if bicarbonate levels change?
As a buffer substance, bicarbonate is often subject to fluctuations caused by the balancing of the pH value through respiration. As a rule, other buffer systems in the body also intervene in these complex regulatory mechanisms, so that special therapy is often not necessary.
Only in emergencies or in seriously ill patients is the body no longer able to regulate the pH balance and bicarbonate via respiration. The administration of chloride can then increase the excretion of bicarbonate and thus reduce elevated values. Conversely, special buffer substances can cause an increase in bicarbonate if it is too low.
