Chloride Imbalance
Hypochloremia and hyperchloremia are chloride imbalances. A deficient serum level of the anion chloride results in hypochloremia; an excessive serum chloride level causes hyperchloremia. A predominantly extracellular anion, chloride accounts for two-thirds of all serum anions.
Secreted by the stomach mucosa as hydrochloric acid, chloride provides an acid medium conducive to digestion and activation of enzymes. It also participates in maintaining acid-base and body water balances, influences the osmolality or tonicity of extracellular fluid (ECF), plays a role in oxygen and carbon dioxide exchange in red blood cells, and helps activate salivary amylase (which, in turn, activates the digestive process).
Causes
Hypochloremia may result from:
decreased chloride intake or absorption, as in low dietary sodium intake, sodium deficiency, potassium deficiency, or metabolic alkalosis; prolonged use of mercurial diuretics; or administration of I.V. dextrose without electrolytes
excessive chloride loss, resulting from prolonged diarrhea or diaphoresis; or loss of hydrochloric acid in gastric secretions caused by vomiting, gastric suctioning, or gastric surgery
hemodilution caused by hypervolemia.
Hyperchloremia may result from:
excessive chloride intake or absorption —as in hyperingestion of ammonium chloride or ureterointestinal anastomosis—allowing reabsorption of chloride by the bowel
hemoconcentration, caused by dehydration
compensatory mechanisms for other metabolic abnormalities, as in metabolic acidosis, brain stem injury causing neurogenic hyperventilation, and hyperparathyroidism.
Complications
Hypochloremia may result in depressed respirations, leading to respiratory arrest. Hyperchloremia may cause coma.
Assessment
The patient’s history may reveal risk factors for hypochloremia or hyperchloremia.
When hypochloremia is associated with hyponatremia, physical assessment may detect characteristic muscle weakness and twitching because renal chloride loss always accompanies sodium loss and sodium reabsorption is not possible without chloride.
However, if chloride depletion results from metabolic alkalosis secondary to loss of gastric secretions, chloride is lost independently of sodium. Inspection may note tetany and shallow, depressed breathing. Neuromuscular assessment may find muscle hypertonicity.
Identifying chloride imbalance
Serum chloride values are key to discerning a chloride imbalance. Use the following guidelines to determine whether your patient has a chloride imbalance.
Hypochloremia: confirmed by a serum chloride level under 95 mEq/L. Supportive values with metabolic alkalosis include a serum pH over 7.45 and serum carbon dioxide levels greater than 32 mEq/L.
Hyperchloremia: confirmed by a serum chloride level greater than 106 mEq/L. With metabolic acidosis, serum pH is under 7.35 and serum carbon dioxide levels are less than 22 mEq/L.
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