Serum Chloride Level

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Serum Chloride Level



Chloride is a mineral that is found throughout the body. Along with other electrolytes (such as sodium, potassium, and carbon dioxide), chloride is involved in maintaining an appropriate fluid balance throughout the body, including an appropriate blood volume; maintaining an stable blood pressure; and equilibrating the pH of the body fluids. For the body to function normally, serum chloride levels have to be maintained at a very narrow range; when chloride levels are too high or too low, it can have serious health consequences. The body keeps its chloride levels in equilibrium by prompting the kidneys to resorb more (when the body needs chloride) or excrete more (when there is excess chloride). When serum chloride levels get too high, the condition is called hyperchloremia. When serum chloride levels get too low, the condition is called hypochloremia.


A serum chloride level is usually drawn as part of a larger panel of electrolytes. Other measurements in the electrolyte panel include sodium, potassium, and carbon dioxide. A serum chloride level is usually checked during a routine physical examination, as well as to evaluate patients who are experiencing prolonged or severe vomiting and/or diarrhea, fatigue, weakness, confusion, muscle spasms, or respiratory distress. Electrolyte panels are frequently used to diagnose, monitor, or otherwise evaluate patients with kidney disease, liver disease, high blood pressure, heart failure, and other chronic conditions.


Serum chloride levels can be affected by a number of medications. Patients who are on these medications should inform their doctor, so that test results can be interpreted appropriately. Medications that may affect serum chloride levels include steroid medications, non-steroidal anti-inflammatory drugs (such as ibuprofen), estrogen-containing medications, male hormones (androgens) some blood pressure medications, cholesterol-lowering agents (such as cholestyramine), and diuretic medications. Another factor that may skew the results of a serum chloride level involves the patient’s level of hydration. When a patient is dehydrated, the serum chloride level will be elevated; when a patient is over-hydrated, the serum chloride level will be artificially lowered.

Patients who are taking anticoagulant medications should inform their healthcare practitioner, since this may increase their chance of bleeding or bruising after a blood test.


This test requires blood to be drawn from a vein (usually one in the forearm), generally by a nurse or phlebotomist (an individual who has been trained to draw blood). A tourniquet is applied to the arm above the area where the needle stick will be performed. The site of the needle stick is cleaned with antiseptic, and the needle is inserted. The blood is collected in vacuum tubes. After collection, the needle is withdrawn, and pressure is kept on the blood draw site to stop any bleeding and decrease bruising. A bandage is then applied.


Addison’s disease— A disease involving decreased functioning of the adrenal glands.

Antidiuretic hormone (ADH)— Also called vasopressin. A hormone produced by the hypothalamus and stored in and excreted by the pituitary gland. ADH acts on the kidneys to reduce the flow of urine, increasing total body fluid. When too much ADH is produced, resulting in the body retaining fluid, the sodium concentration becomes abnormally low.

Cushing’s syndrome— A disorder affecting the adrenal glands and their secretion of coritsol.

Diuretic— A medication that increases the flow of urine through the kidneys and out of the body.

Hyperchloremia— Elevated serum chloride levels.

Hypochloremia— Low serum chloride levels.

Metabolic acidosis— A condition in which either too much acid or too little bicarbonate in the body results in a drop in the blood pH (towards acidity).

Metabolic alkalosis— A condition in which abnormal either too little acid or too much bicarbonate in the body results in an elevation in the blood pH (towards alkalinity).

Respiratory acidosis— A condition in which abnormal exchange of oxygen and carbon dioxide in the lungs results in too much carbon dioxide being accumulated, and a resultant drop in the blood pH (towards acidity).

Respiratory alkalosis— A condition in which abnormal exchange of oxygen and carbon dioxide in the lungs results in the exhalation of too much carbon dioxide, and a resultant rise in the blood pH (towards alkalinity).


There are no restrictions on diet or physical activity, either before or after the blood test.


As with any blood tests, discomfort, bruising, and/or a very small amount of bleeding is common at the puncture site. Immediately after the needle is withdrawn, it is helpful to put pressure on the puncture site until the bleeding has stopped. This decreases the chance of significant bruising. Warm packs may relieve minor discomfort. Some individuals may feel briefly woozy after a blood test, and they should be encouraged to lie down and rest until they feel better.


Basic blood tests, such as serum chloride levels, do not carry any significant risks, other than slight bruising and the chance of brief dizziness.


In adults, a normal serum chloride level is 98-106 milliequivalents per liter (mEq/L, or 98-106 millimoles per liter (mmol/L). In children, a normal serum chloride level is 90-110 milliequivalents per liter (mEq/L, or 90-110 millimoles per liter (mmol/L). In newborns, a normal serum chloride level is 96-106 milliequivalents per liter (mEq/L, or 96-106 millimoles per liter (mmol/ L). In premature infants, a normal serum chloride level is 95-110 milliequivalents per liter (mEq/L, or 95-110 millimoles per liter (mmol/L).

High levels

High serum chloride levels occur whenever there is low blood sodium (hyponatremia), or may also be due to:

  • Dehydration: Increased loss of body water without sufficient replacement by drinking; often occurs in febrile illnesses, with severe diarrhea and/or vomiting, or in situations involving heavy exercise in hot weather, resulting in fluid loss through heavy sweating
  • Hyperventilation
  • Kidney disease
  • Excessive consumption of salt
  • Anemia
  • Use of carbonic anhydrase inhibitors (glaucoma medications)
  • Hyperparathyroidism (an overactive parathyroid gland)
  • Metabolic acidosis
  • Respiratory alkalosis
  • Excess bromide

Low levels

Low serum chloride levels may be due to any disorder that causes low blood sodium (hyponatremia) or may be due to:

  • Cushing’s syndrome
  • Addison’s disease
  • Syndrome of inappropriate ADH secretion (SIADH)
  • Repeated vomiting, or prolonged gastric suction
  • Chronic diarrhea
  • Serious burns
  • Excess sweating
  • Chronic lung diseases, including emphysema and chronic obstructive pulmonary disorder
  • Congestive heart failure
  • Kidney disease
  • Cystic fibrosis
  • Respiratory acidosis
  • Metabolic alkalosis
  • Overhydration



Goldman L, Ausiello D., eds. Cecil Textbook of Internal Medicine. 23rd ed. Philadelphia: Saunders, 2008.

McPherson RA et al. Henry’s Clinical Diagnosis and Management By Laboratory Methods. 21st ed. Philadelphia: Saunders, 2007.


American Association of Clinical Chemistry. 1850 K St., N.W Suite 625, Washington, DC 20006.


National Institutes of Health. [cited February 10, 2008].

Rosalyn Carson-DeWitt, MD