Clinical Information

pH, Feces -

This test may help evaluate carbohydrate malabsorption as the cause of osmotic diarrhea [1].

Osmotic diarrhea is caused by the osmotic effect of a substance that retains water in the intestine lumen. Conditions associated with osmotic diarrhea include ingesting poorly absorbed solutes (eg, sorbitol, mannitol, laxatives containing magnesium) and enzyme dysfunction (eg, lactose intolerance) [1]. In patients with osmotic diarrhea, a stool pH <5.5 may suggest carbohydrate malabsorption when chloridorrhea is excluded, while PH>5.5 is most likely due to other osmotic causes but does not rule out carbohydrate malabsorption [2].

Disruption of the acid-base balance has been observed in patients with various conditions, such as severe systemic inflammatory response syndrome, multiple organ failure, sepsis, and colorectal cancer. Abnormal stool pH has been correlated with higher mortality in patients treated in the intensive care unit [3].

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

References
1. Block DR, et al. Body fluids. In: Rifai R, et al, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.
2. Caspary WF. Clin Gastroenterol. 1986;15(3):631-655.
3. Osuka A, et al. Crit Care. 2012;16(4):R119.