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Test Catalog

Test ID: HQ    
HemoQuant, Feces

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of blood in feces

 

Evaluation of iron deficiency

 

Detection of bleeding as a complication of anticoagulant therapy and other medication regimens

 

This test is not specific for bowel cancer.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Several noninvasive tests are available to detect gastrointestinal (GI) bleeding. However, guaiac type and immunochemical tests for occult bleeding are affected by the presence of reducing or oxidizing substances and are insensitive for the detection of upper GI tract (esophagogastric) bleeding, where most clinically significant occult GI bleeding occurs.

 

The HemoQuant test is the most reliable, noninvasive test currently available for detecting bleeding of the esophago-GI tract. Unlike other tests for blood in feces, this test detects both intact heme and porphyrins from partly degraded heme. Additionally, test results are not complicated by either the water content of the specimen or the presence of reducing or oxidizing substances. Furthermore, HemoQuant testing is sensitive to both proximal and distal sources of occult GI bleeding. HemoQuant is the most appropriate fecal occult blood test to use in the evaluation of iron deficiency.

 

Normally, one gram of feces may contain 0.0 - 2.0 mg hemoglobin (Hb); this corresponds to a daily loss of up to 2-mL blood. A demonstration of increased Hb in feces indicates bleeding in the alimentary tract (or ingestion of anticoagulants, aspirin, or red meat).

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Normal:

< or =2.0 mg total hemoglobin/g feces

Marginal:

2.1-4.0 mg total hemoglobin/g feces*

*2.1-4.0 mg Hb/g is considered marginally elevated, but not clinically significant, if red meat, warfarin, or aspirin was ingested 72 hrs prior to collection.

Elevated:

>4.0 mg total hemoglobin/g feces

Interpretation Provides information to assist in interpretation of the test results

Elevated levels are an indicator of the presence of blood in the feces, either from benign or malignant causes.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Heme from ingested red meat will increase HemoQuant test values. Patients should be advised to avoid eating red meat for 3 days before collecting specimens. Fish and poultry may be substituted.

 

The elevated porphyrins of lead intoxication, erythrocytic protoporphyria and variegate porphyria may raise HemoQuant values in the absence of gut bleeding.

 

Recent studies have indicated that cancerous lesions in their early stages often do not bleed or bleed only intermittently.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Ahlquist DA, McGill DB, Schwartz S, et al: HemoQuant, a new quantitative assay for fecal hemoglobin: comparison with Hemoccult. Ann Intern Med. 1984;101:297-302

2. Ahlquist DA, Wieand HS, Moertel CG, et al: Accuracy of fecal occult blood screening for colorectal neoplasia: a prospective study using Hemoccult and HemoQuant tests. JAMA. 1993;269:1262-1267

3. Harewood GC, McConnell JP, Harrington JJ, et al: Detection of occult upper gastrointestinal bleeding: performance differences in fecal blood tests. Mayo Clin Proc. 2002;77(1):23-28

4. Ahlquist DA, McGill DB, Schwartz S, Taylor WF, Owens RA: Fecal blood levels in health and disease: A study using HemoQuant. N Engl J Med. 1985 May 30;312(22):1422-1428

5. Barber MD, Abraham A, Brydon WG, et al: Assessment of faecal occult blood loss by qualitative and quantitative methods. J R Coll Surg Edinb. 2002;47(2):491-494