Chloride
Also called: Cl-
Chloride is the body's most abundant negative-charge ion, partnered closely with sodium in fluid balance and stomach acid. It's a routine electrolyte panel marker.
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What does Chloride measure?
Chloride is the principal anion of extracellular fluid; it moves with sodium to maintain osmotic balance, supplies the Cl⁻ for stomach hydrochloric acid, and shifts in and out of red blood cells in a buffer system (the chloride shift) that helps regulate blood pH. Lab chloride is rarely interpreted alone — it earns its place in basic metabolic and comprehensive metabolic panels alongside sodium, potassium and bicarbonate, where the four together reveal acid-base, fluid and renal pictures the single values would miss.
What does a high Chloride level mean?
- Dehydration — pure water loss concentrates chloride alongside sodium.
- Metabolic acidosis with normal anion gap — diarrhoea, renal tubular acidosis, saline-loading.
- Renal failure — impaired chloride excretion.
- Cushing's syndrome / steroid use — sodium and chloride retention.
- Respiratory alkalosis — compensation pulls chloride into cells.
What does a low Chloride level mean?
- Prolonged vomiting or gastric drainage — loss of HCl from the stomach.
- Diuretic therapy — particularly loop diuretics.
- Congestive heart failure with diuresis — combined fluid + electrolyte loss.
- Metabolic alkalosis — Cl⁻ moves out of plasma.
- SIADH, Addison's disease, severe burns — usually paired with low sodium.
When to discuss with a doctor
Isolated mildly abnormal chloride rarely needs action; it's the pattern with sodium, potassium and bicarbonate that drives the clinical picture. Values outside 95–110 mmol/L paired with another abnormal electrolyte, recent vomiting/diuretic use, or symptoms (muscle cramps, lethargy, confusion) warrant a primary-care visit. Mediora.AI shows chloride next to its electrolyte siblings so the pattern is obvious; we do not diagnose acid-base disorders.