• Hypochloremia can be caused by a total chloride deficit, dilutional condition, or acid-base disorder.

  • Chloride is the most abundant anion in the extracellular fluid compartment.

  • The primary drivers of chloride homeostasis are:

    • Passive equilibration with sodium
    • Chloride-bicarbonate anion exchange in the kidney, such that bicarbonate excretion is exchanged for chloride resorption (and vice versa)

Causes [1]

Special Populations


Consider the below conditions with hypochloremia, specifically in the setting of metabolic alkalosis. A urinary chloride level will help differentiate these conditions [2].

  • Gastrointestinal
    • Nasogastric tube suction, such as in NICU and PICU settings
    • Severe gastroesophageal reflux
    • Pyloric stenosis
    • Laxative abuse
    • Congenital chloride diarrhea
  • Renal
    • Diuretic use
    • Chloride-losing nephropathy
    • Bartter Syndrome: Genetic defect in chloride transport in kidney
    • Gitelman Syndrome: Familial hypokalemia-hypomagnesemia from renal inability to resorb salts
  • Skin
    • Cystic fibrosis

The lower end of the normal reference range for chloride levels are slightly different than for adults, especially for those older than 2-3 months old [3].

Pediatric AgeHypochloremia definition
Premature infantCl <95 mEq/L
NewbornCl <96 mEq/L
ChildCl <90 mEq/L


There are no pregnancy-specific causes for hyperchloremia, although the lower end of the normal reference range may be slightly higher in the first trimester [4].

Trimester StageHypochloremia definition
FirstCl <101 mEq/L
SecondCl <97 mEq/L
ThirdCl <97 mEq/L

Originally published Feb 12, 2023 (updated February 13, 2023)


  1. Morrison G. Serum Chloride. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 197.
  2. Desai J. Hypochloremic Metabolic Acidosis. Medscape Section on Pediatrics: Genetics and Metabolic Disease. Published Aug 30, 2018.
  3. Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. St. Louis, MO: Elsevier; 2019.
  4. Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009 Dec;114(6):1326-1331. doi: 10.1097/AOG.0b013e3181c2bde8. Erratum in: Obstet Gynecol. 2010 Feb;115(2 Pt 1):387. PMID: 19935037.


Lin M, Lopes G. Lab It Up: Hypochloremia. Academic Life in Emergency Medicine. https://www.aliem.com/lab-it-up-hypochloremia/. Feb 12, 2023.

Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at https://t.co/50EapJORCa Bio: https://t.co/7v7cgJqNEn
Michelle Lin, MD
Gabriella Lopes, MD

Gabriella Lopes, MD

Emergency Medicine Resident
Department of Emergency Medicine
University of California, San Francisco
Gabriella Lopes, MD

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