BASICS
- Chloride is the major anion in the extracellular fluid
- Serum chloride concentrations may increase and decrease in proportion to changes in serum sodium concentrations; these proportional increases and decreases relate to changes in body water and sodium homeostasis
- Changes in serum chloride concentrations not proportional to those in serum sodium concentrations usually relate to acid–base abnormalities
- Serum chloride concentrations tend to vary inversely with serum bicarbonate concentrations
- Metabolic acidosis with a normal or low AG may be accompanied by hyperchloremia; in metabolic acidosis with a high AG, serum chloride concentration is normal or low
- Hyperchloremia may also occur when the serum bicarbonate concentration decreases in compensation for respiratory alkalosis
- Dependent on the underlying cause
- Neuromuscular—severe hypernatremia and hyperchloremia, resulting in marked hyperosmolality, may cause neurologic abnormalities because of water loss from neurons
Chloride Increased Proportionately to Sodium
- High total body chloride—excessive NaCl intake (i.e. salt poisoning) with water restriction (rare)
- Iatrogenic causes—administration of excessive hypertonic NaCl
- Normal total body chloride with excessive free water loss—inadequate water intake, early stages of diarrhea, central or nephrogenic diabetes insipidus, prolonged hyperventilation
Chloride Increased Disproportionately to Sodium
- Metabolic acidosis with a low or normal AG—RTA, an uncommon disorder in horses, results in striking hyperchloremia, hypobicarbonatemia (especially with proximal type II RTA) and metabolic acidosis
- Compensated respiratory alkalosis—decreased bicarbonate as a compensatory response results in increased chloride
- Acetazolamide treatment for hyperkalemic periodic paralysis
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS