pH, Feces

Test Codes

EPIC: LAB1975, Beaker: pH feces, Quest: 1304

Department

Send Outs

Instructions

Adult and older children patients can collect the specimen by passing feces into plastic wrap stretched loosely over the toilet bowl. Then transfer 5 g of the stool specimen into the plastic container. With young children and infants wearing diapers, the diaper should be lined with clean plastic wrap to prevent absorption. A pediatric urine bag can be attached to the child to ensure that the stool specimen is not contaminated with urine. Then transfer 5 g of the stool specimen from the plastic lined diaper to the plastic container. Do not submit the diaper itself. Freeze and transport frozen.

Specimen Collection Criteria

Collect: Random liquid or soft stool specimen collected in sterile plastic container.

Physician Office/Draw Specimen Preparation

Freeze (-20°C/-4°F or below) specimen after collection and prior to transport.

Preparation for Courier Transport

Transport: 5.0 g Stool in a sterile collection container, frozen (-20°C/-4°F or below). (Minimum: 1.0 g)

Rejection Criteria

• Received thawed.
• Specimens not collected and processed as indicated.

In-Lab Processing

Freeze (-20°C/-4°F or below) specimen after collection and prior to processing.

Transport: Stool in a sterile collection container, frozen (-20°C/-4°F or below). (Minimum: 1.0 g)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): 24 hours.
Frozen (-20°C/-4°F or below): 60 days.

Specimen Storage in Department Prior to Disposal:

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Sunday – Friday.
Results available within 2-4 days.

Reference Range

Newborns (Neonates) Birth through 28 days	5.0-7.0 pH units
Infants >1 month through 2 years
Bottle Fed; Neutral or slightly alkaline	≥7.0 pH units
Breast fed; slightly acidic	<7.0 pH units
>2 Years	7.0-7.5 pH units

Test Methodology

Potentiometry

Clinical Utility

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 (e.g., sorbitol, mannitol, laxatives containing magnesium) and enzyme dysfunction (e.g., 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.

Reference

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.

CPT Codes

83986
LOINC: 2755-7

Contacts

Last Updated

11/19/2025