Chloride, Feces

Submit a frozen specimen of watery liquid feces in a plastic screw-cap container. Keep feces refrigerated during collection and transport frozen. Only watery liquid feces are an acceptable specimen. In the event a formed fecal specimen is submitted, the test will not be performed and will be cancelled.

Note: Specimen must be shipped frozen to reduce the odor during shipping and to minimize the risk of the container rupturing due to gas accumulation.

This test only has clinical utility if performed on a watery fecal specimen.

Stable up to 3 freeze-thaw cycles.

Measurements of chloride in conjunction with other electrolytes in liquid stool may help differentiate between secretory and osmotic diarrhea. This test may also aid in the diagnosis of primary or secondary chloridorrhea.

Diarrhea can be categorized as secretory or osmotic depending on how the water content of stool is drawn in the intestine lumen. Secretory diarrhea is caused by defective electrolyte absorption that increases the stool's electrolyte levels. Conditions associated with secretory diarrhea include infection, neuroendocrine tumors, intestinal resection, diffuse mucosal disease, and congenital chloridorrhea [1]. Congenital chloridorrhea is a rare autosomal-recessive disorder characterized by watery stool containing excessive chloride. Stool chloride levels during perinatal period and infancy are often greater than 120 mmol/L [2]. Similar to congenital chloridorrhea, acquired chloridorrhea may manifest as hypochloremia, metabolic alkalosis, and no chloride in the urine, but the magnitude of excess chloride excretion in the stool is usually less [3].

Low levels of stool chloride may be seen in sodium sulfate-induced diarrhea [4].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Schiller LR. Pract Res Clin Gastroenterol. 2012;26(5):551-562.
2. Konishi KI, et al. J Pediatr. 2019;214:151-157.e6.
3. Kaplan BS, et al. J Pediatr. 1981;99(2):211-214.
4. Eherer AJ, et al. Gastroenterology. 1992;103(2):545-551.