Acid-base and electrolyte abnormalities with diarrhea
- Michael Emmett, MD
Michael Emmett, MD
- Section Editor — Fluid and Electrolytes
- Chief of Internal Medicine
- Baylor University Medical Center
- Biff F Palmer, MD
Biff F Palmer, MD
- Professor of Internal Medicine
- University of Texas Southwestern Medical Center
Diarrhea can cause a variety of fluid volume, acid-base, and electrolyte abnormalities. The alterations in serum chemistries that can occur, their etiologic mechanisms, and the issues related to diagnosis and treatment are reviewed in this topic.
FLUID AND ELECTROLYTE CONTENT OF NORMAL STOOL
The composition of normal stool must be known in order to understand the consequences of diarrhea:
●Normal stool has an alkaline pH.
●Sodium and potassium salts are the primary stool solutes. The sodium plus potassium concentration in stool usually ranges between 130 and 150 meq/L. Other cations, such as calcium and magnesium, are present at much lower concentrations.
●The main inorganic stool anions are bicarbonate (about 30 meq/L), chloride (about 10 to 20 meq/L), and a small amount of phosphate and sulfate.
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- FLUID AND ELECTROLYTE CONTENT OF NORMAL STOOL
- FLUID, ELECTROLYTE, AND NON-ELECTROLYTE CONTENT OF DIARRHEA
- ACID-BASE, ELECTROLYTE, AND VOLUME ABNORMALITIES ASSOCIATED WITH DIARRHEA
- Metabolic acidosis
- - Serum anion gap in patients with metabolic acidosis due to diarrhea
- - Evaluating the renal response to metabolic acidosis in patients with diarrhea
- Urine pH and urine ammonium and sodium concentrations
- Metabolic alkalosis
- - Congenital chloride wasting diarrhea
- - Laxative abuse