What is chloride?
The chloride (Cl-) is the major anion (negatively charged ion) and electrolyte present in the blood serum and the extracellular fluid.
AdvertisementsIt is an essential nutrient required along with sodium and potassium for maintaining fluid and electrolyte balance in the human body. Deficiency of chloride is rare.
The normal chloride levels in blood serum range from 97 to 107 mEq/L. Cl- deficiency (hypochloremia) occurs when the levels drop below 97 mEq/L. Low serum chloride levels disturb the acid and base balance in the body. Chronic low Cl- levels can leading to metabolic alkalosis, low fluid volume in the blood serum and urinary potassium loss.
Chloride food sourcesThe primary source of Cl- is the sodium chloride, the common table salt. It is also present in seaweeds such as dulse (Palmaria palmata) and kelp. Pickled and processed foods are good sources of chloride and sodium.
The Food & Nutrition Board of the Institute of Medicine, has set the daily Adequate Intake (AI) of chloride for adults (19 to 50 years) as 2.3 grams per day. Individuals in the older age group (50+ years) may need 2.0 grams/day. Intake levels lower than the AI can cause deficiency. The Tolerable Upper Intake Levels (UL) for Cl- for adults is 3.6 grams/day.
Chloride benefits and functions
- Chloride is a component of all body secretions and excretions.
- Cl- is an essential component of digestive juices, occurring as stomach hydrochloric acid.
- It is involved in the regulation of pH of the body fluids and blood serum.
- A constant exchange of chloride and bicarbonate, between red blood cells and the serum helps to govern the pH balance.
- Chloride shift (also known as the Hamburger shift) brings about the transport and expiration of carbon dioxide.
- The Cl- shift may also regulate the affinity of hemoglobin for oxygen.
- Low levels of Cl- in the blood serum leads to increase in pH, metabolic alkalosis and contraction of the extracellular volume with serious symptoms.
- Cl- ions channels render nerve cells more excitable and have a pivotal role in neurotransmission.
Chloride deficiency causesLow Cl- levels may occur for a variety of reasons including,
- severe dietary insufficiency,
- acute severe malnutrition,
- eating disorders (anorexia nervosa and bulimia),
- malabsorption disorders,
- excessive perspiration,
- persistent vomiting,
- severe chronic diarrhoea,
- fluid loss due to burns and injuries,
- overuse of diuretics or laxatives,
- drinking too much water,
- congenital chloride diarrhea,
- renal disease,
- salt-wasting nephropathy,
- congestive heart failure,
- cystic fibrosis,
- Bartter’s syndrome and
- genetic diseases.
Symptoms of low levels of chloride in bloodIn mild low levels of Cl- in blood, the symptoms may not be apparent. Milder symptoms include loss of appetite, muscle weakness, dehydration, fever and restlessness. Marked low serum levels of the nutrient can manifest with symptoms like loss of control of muscle function, difficulty in breathing and swallowing. Very low Cl- in blood serum shows symptoms of alkaline blood, very high serum pH, massive loss of potassium in urine and hypokalemic metabolic alkalosis.
Diagnosis of low serum chloride levelsLow blood Cl- levels (less than 97 mEq/L) confirm the diagnosis. Simultaneously, pH and carbon dioxide levels are tested. Blood pH rises beyond 7.45. Serum carbon dioxide levels rises above 32 mEq/L.
Chloride deficiency diseasesThis condition is medically termed as hypochloremia. It is usually the result of low sodium levels or elevated bicarbonate concentration in the blood serum due to volume depletions. Low blood serum concentration of Cl- ion is a rare condition. However, when it does occur, it results in a life threatening metabolic alkalosis, low fluid in the blood serum, contraction of the extracellular volume and urinary potassium loss. Certain genetic diseases like congenital chloride diarrhea can contribute to low blood serum concentration of this electrolyte.
Congenital chloride diarrheaCongenital chloride diarrhea is due to mutations in the SLC26A3 gene. These mutations impair the synthesis of intestinal SLC26A3 protein, resulting in impaired exchange of Cl-/HCO3- ions. The mutation results in diarrhea-related Na+, Cl- and fluid depletion resulting in decreased blood serum concentration of these ions.
Treatment of low serum chloride levelsIV administration of saline is the best treatment option for correcting the electrolyte imbalance. Ammonium chloride may be administered for treating the metabolic alkalosis. The causative factors are treated for complete resolution of the condition. Hypochloremia can be prevented by consuming food moderately high in this electrolyte.
References on low levels of Cl- ions in blood serum:|
1.Grossman H, Duggan E, McCamman S, Welchert E, Hellerstein S. The dietary chloride deficiency syndrome. Pediatrics. 1980 Sep;66(3):366-74.
2.Chipperfield AR, Harper AA. Chloride in smooth muscle. Prog Biophys Mol Biol. 2000;74(3-5):175-221.