What is chloride?
As a vital electrolyte, more than half (approx. 56%) of the chloride in the body is found outside the cells in the so-called extracellular space. About a third (approx. 32%) is found in the bones and only a small proportion (12%) inside the cells (intracellular space).
The distribution of electrolytes and their electrical charge creates an electrical voltage (potential difference) between the inside and outside of the cell. This is also known as the resting membrane potential. If the voltage changes due to the inflow and outflow of sodium, potassium and other electrolytes, an action potential develops. This serves to transmit signals between cells in the body, for example between nerve cells or between nerve and muscle cells.
Thanks to its negative charge, chloride in the body can transport electrolytes with a positive charge (cations) across membranes without changing the voltage. Other substances can also only be transported through cell membranes via chloride channels when bound to chloride.
Together with other factors, chloride also regulates the distribution of water in the body and the acid-base balance. It is not only found in the bones and blood, but also in sweat and stomach acid, where it contributes to digestion.
Absorption and excretion of chloride
Daily chloride requirement
The average daily requirement for chloride is estimated at 830 milligrams. Children and infants require less chloride, while excessive sweating increases the requirement. In total, the human body contains around 100 grams of chloride.
When is chloride determined in the blood?
Chloride is usually determined to assess the acid-base balance. Chloride values can also be used to monitor the sodium and water balance. For this reason, the chloride value is always assessed in conjunction with other electrolytes such as sodium, potassium, calcium and magnesium.
Chloride standard values
The chloride level in serum and plasma is used as a control value:
|
Blood (mmol/l) |
|
|
Adults |
96 – 110 mmol/l |
|
Children, infants, newborns |
95 – 112 mmol/l |
In the event of a chloride deficiency, a urine test provides more detailed information: the chloride value in the urine can be used to determine whether the patient is excreting too much chloride via the kidneys or the intestines, for example in the case of hereditary diseases. The total amount excreted within 24 hours is measured in the urine (24-hour urine). Although this depends on the diet, it should be between 100 and 240 mmol.
When is chloride in the blood low?
A chloride deficiency is also known as hypochloremia or hypochloridemia. One possible cause is an increased loss of chloride, for example due to:
- vomiting
- Taking certain dehydration tablets (diuretics)
- kidney weakness (renal insufficiency)
- Congenital chloride diarrhea (congenital chloridorrhea)
The loss of chloride increases the pH value (alkalosis) and results in hypochloremic alkalosis. Conversely, the complex system for compensating for disorders of the pH value also leads to hypochloremia if alkalosis exists for other reasons:
- Excess aldosterone (hyperaldosteronism)
- Cushing’s syndrome
- Respiratory insufficiency
- SIADH syndrome (Schwartz-Bartter syndrome)
While a mild chloride deficiency hardly shows any symptoms, patients with alkalosis develop general weakness, cramps and nausea, among other things.
When is chloride elevated in the blood?
If chloride is elevated, this is also referred to as hyperchloremia or hyperchloridemia. Too much chloride mainly accumulates in the case of congenital or acquired disorders of the acid-base balance, in which acidosis develops in the body and the pH value falls. The kidneys reduce chloride excretion in order to compensate for the acidosis. Possible causes of increased chloride levels:
- Excessive breathing (hyperventilation)
- Autoimmune diseases
- Kidney diseases (interstitial nephropathy)
- Operations on the urinary tract
- Diabetes (diabetes mellitus)
- Diarrhea
What to do if the chloride is increased or decreased?
Both hypochloremia and hyperchloremia must always be treated depending on their origin.
If the chloride level is only slightly reduced, an increased salt intake or an infusion usually helps. Renal insufficiency must be treated as quickly as possible in hospital, including with increased fluid intake. Severe deviations in the chloride level should always be treated by a doctor.
If the chloride is chronically elevated, those affected should generally eat a low-salt diet and drink plenty of fluids. In general, however, the treatment of hyperchloremia also depends on the disease.
