c14 urea breath test

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14C-Breath Test

This lecture will discuss the 14C-Urea Breath test.

By the end of the talk you will know:- indications for the test- patient preparation and contradictions - how the test is administered- lab work required

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14C-Urea Breath Test

14C is used to assess the effectiveness of treatment for Helicobacter pylori (H. pylori).

H. pylori is a Gram-negative bacteria associated with:- peptic ulcers - gastritis

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14C-Urea Breath Test

14C is produced by: 14N(n,p)14C

14C decays to 14N, giving off a -

The - energy is 160 keVmax (49) keVmean 14C half life is 5730 years

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14C-Urea Breath TestThe infection rates of H. pylori is: Up to to 80% of the adult population in Puerto Rico. Almost 50% in adults in North America over 50 yrs old.

Only 10% to 20% of the people who have H. pyloridevelop peptic ulcers.

The bacteria is spread by: - mouth/mouth - fecal/mouth

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14C-Urea Breath Test

H. pylori is associated with peptic ulcers and gastritis.

The best method of ulcer treatment is a combination of:• Antibiotics (e.g.: metronidazole, tetracycline)• Proton pump inhibitors (Prilosec, Prevacid…)• Bismuth subsalicylate (Pepto-Bismol)

The above treatment results less than 5 to 10 % re-occurrence in 1 year. In contrast, without the above combined treatment the recurrence over 1 year is 80 to 100%.

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14C-Urea Breath TestThe primary indication for this test is the verification of treatment for the eradication of H.pylori. bacteria. This verification can be done one month after treatment.

Serology tests can remain positive for 6 - 12 months. The 14C test can give results one month after the completion of treatment. This means: blood work can detect the problemwhile the 14C test can indicate if therapy was successful.

The 14C test has:A sensitivity (true positive) of 90 to 100 %A specificity (true negative) of 78 to 100 %

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14C-Urea Breath Test

Contraindications:Still on ulcer treatments.

Patient preparation:NPO for 6 hours.Off medications for 4 weeks

(antibiotics, proton pump inhibitors, bismuth).

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14C-Urea Breath Test

The 14C-urea tablet is metabolized by H.pylori producing CO2 and NH4.

The 14CO2 is absorbed by the blood system and exhaled by the lungs. The exhaled radioactive 14CO2 can be collected and measured.

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14C-Urea Breath Test

Protocol summary:

1) Patient swallows a 37kBq 14C-urea capsule with 20 ml of water.

2) 3 minutes later 20 ml more of water consumed.

3) 10 minutes after step ‘2)’ a standard balloon is inflated by the patient.

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14C-Urea Breath Test

Processing summary:The volume of the balloon is drawn out into a trapping solution to capture the CO2. A scintillation cocktail is added to the vial. The vial is place in a scintillation counter.

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14C-Urea Breath Test

The 14C beta particles cause scintillations in the solution.Evaluation of results for a 10 minute period:

< 50 cpm indicates NO H.pylori is present.50 - 199 cpm is inconclusive.200+ cpm indicates H.pylori IS present.

False negatives (no H.pylori present) can be caused by:Not off indicated medications long enough.Not NPO long enough.

False positive (H.pylori present) can be caused by:Gastric surgery.

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14C-Urea Breath Test

Dose to patient is 0.003 mSV.(Equivalent to ~1 day of background radiation)

Critical organ: Bladder wall.

Mode of elimination:Exhaling and urination.

Physical half life of 14C is 5730 years. Biological half life of 14C is 40 days.

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Summary

The 14C- Urea breath test is an accurate method to assess the effectiveness of treatment for gastric ulcersand H. pylori.

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References

Blaser, M., (2005). An endangered species in the stomach. Scientific America, February 2005

Ingraham, J., Ingraham, C., (2004) Introduction to microbiology. (3 rd ed.) Belmont, CA: Brooks/Cole

Kumar, V., Cotran, R., Robins, S., (2003) Basic Pathology. (7 th ed.) Philadelphia, PA: Saunders

Page, C., Curtis, M., Hoffman, B., Sutter, M., Walker, M., (2002). Integrated Pharmacology. Toronto: Mosby

SNM (2001). Procedure Guide for C-14 Urea Breath Test. Version 3.0 The Ottawa Hospital. (2004) C-14 Breath Testing for H. Pylori. Nuc13 (01/2004) and PYtest Information Sheet

Taylor, A., Schuster, D., Alazaki, N. (2006). A Clinician’s Guide to Nuclear Medicine. (2nd ed.) SNM: Reston, VA

Wilson M. (1998). Textbook of Nuclear Medicine. Philadelphia: Lippencott-Raven

Ziessman, A. Harvey, O’Malley, P. Janis, Thrall, H. James (2006) The Requisites of Nuclear Medicine (3 rd ed.) Philadelphia, PA: Elsevier Mosby