Detect occult blood.

Lack of sensitivity to small amounts of blood, might fail to detect slower rates of blood loss. Even more sensitive tests (guaiac) are positive in only 50% of patients with colon cancer. At least three specimens, preferably of separate bowel movements, should be submitted. Vitamin C, ascorbic acid, may cause false-negatives. False-positive results may be caused by excessive dietary intake of vegetable peroxidases, especially horseradish, and by methyl bromide and methyl iodide.

Daily

Guaiac is a leuko-dye. The peroxidase-like activity of hemoglobin or nonspecific oxidants catalyze the reaction of peroxide and the chromogen ortho-toluidine to form blue oxidized ortho-toluidine.

Reference Laboratory: 24 hours. UIMCC: 4 hours.

Core Laboratory, Hematology

Of 45 patients with at least one positive Hemoccult® test on three stools, 80% were found to have a colonic lesion; this included nine carcinomas. Methods for examination of stool for occult blood utilize peroxidation of a chromogen by stool peroxidases. Hemoglobin acts as a peroxidase, but stool may also contain meat, bacterial and plant peroxidases (eg, beef, mutton, salmon, sardines, soups with dark meats, yellow turnips, horseradish, apples, oranges, and bananas). Normal intestinal blood loss averages 2.0-2.5 mL. Hemoccult? begins to turn positive at about 5.0 mg hemoglobin/g stool, which is said to be the upper limit of normal stool peroxidase activity. Hemoccult® is a modified Guaiac which is designed to be and is less sensitive; its claimed incidence of false-positives (1% to 12%) is less than that of other current methods.

Drug Guidelines:

• For seven days before and during the stool collection period, avoid nonsteroidal anti-inflammatory drugs such as ibuprofen, naproxen or aspirin (more than one adult aspirin a day).

• Acetaminophen (Tylenol®*) can be taken as needed.

• For three days before and during the stool collection period, avoid vitamin C in excess of 250 mg a day from supplements, and citrus fruits and juices.

*Tylenol® is a registered trademark of McNeil Consumer Products.

Diet Guidelines:

• For three days before and during stool collection period, avoid red meats (beef, lamb and liver).

• Eat a well balanced diet including fiber such as bran cereals, fruits and vegetables.

Notes:

1. Please talk to your doctor or pharmacist if you have any questions about medications you take regularly.

2. 100% of RDA of vitamin C for an adult is 60 mg a day.

3. Some iron supplements contain vitamin C in excess of 250 mg.

4. Therapeutic iron causes false-positives with guaiac tests in >50% of healthy subjects. Alcohol and aspirin, especially together, and other gastric irritants (steroids, rauwolfia derivatives, all nonsteroidal anti-inflammatory drugs, colchicine) should also be avoided.

5. Halogens and cimetidine can cause reactions with guaiac tests.

Card with stool smear or 5 g stool Card with stool smear or stool, Collection card or stool transport vial without preservatives.

Specimen contaminated with urine, improper container, specimen on outside of container, frozen specimen, specimen in preservative.

Transport: Reference Laboratory: Stool specimen: 2°C to 8°C; occult blood cards: Ambient. UIMCC: Stool specimen and/or occult blood cards: Ambient.

Stability: Ambient: Stool: 1 hour; Cards: 14 days. Refrigerated: Stool: 36 hours; Cards: Unacceptable. Frozen: Stool: Unacceptable; Cards: Unacceptable.

Daily

1 g stool

Occult blood card: Specimens from 2 different locations on the stool should be smeared on each of the 2 test areas of the occult blood card. The card must be identified with the patient's name, birth date, medical record number (UIMCC), and sealed in a biohazard bag. Plastic stool container: Stool identified with patient's name, in biohazard bag.

Occult Blood: Unspecified: Negative
Occult Blood, 2nd specimen: Unspecified: Negative
Occult Blood, 3rd specimen: Unspecified: Negative
 

82270 (screening, 1-3 cards, single determination)