pH, Stool

CPT: 83986
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  • Fecal pH
  • Stool pH

Expected Turnaround Time

3 - 5 days

Related Documents

Specimen Requirements


Stool (fresh random)


1 g

Minimum Volume

0.5 g


Clean container

Storage Instructions

Room temperature

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Patient Preparation

Barium procedures and laxatives should be avoided for one week prior to collection of the specimen.

Causes for Rejection

Specimen contaminated with urine; specimen on outside of container

Test Details


Detect carbohydrate and fat malabsorption; evaluate small intestinal disaccharidase deficiencies


This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the Food and Drug Administration.


Aqueous stool suspension measured with pH paper

Reference Interval

pH: 0 to 6 months: 4.5–5.5

>6 months: 7.0–7.5

Additional Information

Stool pH is dependent in part on fermentation of sugars. Colonic fermentation of normal amounts of carbohydrate sugars and production of fatty acids accounts for the normally slightly acidic pH. If disaccharide intolerance is suspect, simple tests may be performed. Slightly alkaline pH may occur in cases of secretory diarrhea without food intake, colitis, villous adenoma, and possibly with antibiotic usage (with resultant impaired colonic fermentation). A stool pH of <6 (measured by pH paper) is suggestive evidence of sugar malabsorption. Children and some adults notice that their stools have a sickly sweet smell as the result of volatile fatty acids and the presence of undigested lactose. Low stool pH also contributes to the excoriation of perianal skin which frequently accompanies the diarrhea.1

High fecal pH may be a risk factor for colorectal cancer.2-6 Intake of oat bran (75−100 g/day over a 14-day period) has been shown capable of reducing fecal pH by 0.4 units.2 There is evidence, however, that high fecal pH may be secondarily rather than primarily related to cancer risk.3


1. Cooper BT. Lactose deficiency and lactose malabsorption. Dig Dis. 1986; 4(2):72-82 (review). 3102130
2. Kashtan H, Stern HS, Jenkins DJA, et al. Manipulation of fecal pH by dietary means. Prev Med. 1990 Nov; 19(6):607-613. 2263571
3. Kashtan H, Gregoire RC, Bruce WR, Hay K, Stern HS. Effects of sodium sulfate on fecal pH and proliferation of colonic mucosa in patients at high risk for colon cancer. J Natl Cancer Inst. 1990 Jun 6; 82(11):950-952. 2342129
4. Thornton JR. High colonic pH promotes colorectal cancer. Lancet. 1981 May 16; 1(8229):1081-1083. 6112450
5. Malhotra SL. Faecal urobilinogen levels and pH of stools in population groups with different incidence of cancer of the colon, and their possible role in its aetiology. J R Soc Med. 1982 Sep; 75(9):709-714. 7120255
6. Walker AR, Walker BF, Walker AJ. Faecal pH, dietary fibre intake, and proneness to colon cancer in four South African populations. Br J Cancer. 1986 Apr; 53(4):489-495. 3011051


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
010991 pH, Stool 2755-7 010991 pH, Stool 2755-7
Reflex Table for pH, Stool
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 000000

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