Acid base balance

Acidity is important for virtually all body processes and is therefore strictly regulated. The acidity in the body is determined by the balance between acids (e.g., hydrogen ions (H +) or ammonia) and bases (e.g., bicarbonate) and is expressed as pH. The pH in the blood ranges between 7.35 and 7.45.

Acidosis and alkalosis
Disturbances of this balance, and thus the acidity, may lead to a so-called acidosis (acidification by too much acid or too little bases, the pH drops), or an alkalosis (too much bases or too little acids; the pH increases).

In order to arrange the balance of the amount of acids and bases, the body has various regulating mechanisms. The body can get rid of the acid by breathing out acid in the form of CO2 (carbon dioxide). By breathing faster, more carbon dioxide will be exhaled and pH rises. By breathing slowly, less carbon dioxide is exhaled and the pH decreases. Adjustment of breathing can be done quickly.
The kidneys also have an important role in maintaining the acid-base balance. The kidneys can secrete acid (for example as H +, phosphate acid, and via ammonia) and reabsorb bases (bicarbonate). These processes are dependent on the sodium and chloride content offered to the renal tubules. With a disorder in one of these processes, a patient may develop an abnormal acidity (acidosis or alkalosis).

Signs and symptoms
Patients with acidosis or alkalosis can have various complaints such as shortness of breath and tingling. The complaints are particularly subject to additional disturbances in the uptake and excretion of salts and minerals.

Determinining the cause
The diagnosis is based on blood and urine tests in which an abnormal acidity level (pH) is caused by breathing disturbances (respiratory acidosis or alkalosis) or caused by abnormalities in the metabolism (metabolic acidosis or alkalosis). Additional tests can be performed depending on which specific condition is suspected. For example, a renal tubular acidosis (acidification of the blood by a problem in the renal tubules) is examined with special function tests. For a description of specific diseases which can occur an acid-base disturbance, see the links below.

–    Renal tubular acidosis
–    Gitelman syndrome
–    Bartter syndrome