Chloride is the main negatively charged ion outside the cells and normally follows sodium closely. It contributes to osmolality, to fluid distribution and to acid-base balance, since it exchanges with bicarbonate. It is measured mainly to refine the picture given by the other electrolytes rather than on its own.
No readings for this marker yet.
Raised chloride most often accompanies dehydration with water loss, and appears in metabolic acidosis where bicarbonate is lost through the gut or the kidneys, or after large volumes of saline. Lowered chloride most often follows prolonged vomiting or gastric drainage, diuretic use, and chronic lung disease with carbon dioxide retention. Because chloride tracks sodium, changes in the same direction as sodium usually point at water balance, while divergent movement points at an acid-base disturbance. Interpretation belongs with a doctor rather than with the number alone.
Very high blood fats or protein can distort the measured concentration, and bromide-containing preparations interfere with some assays. Recent infusions, vomiting or diuretics on the day of the draw shift the result. Chloride is read together with sodium, potassium and bicarbonate, most often through the anion gap.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.