1. This is an invitro procedure that is designed to detect the presences of Helicobacter pylori (HP) which is a bacteria associated with peptic ulcer disease (PUD)
   1. Patients that have HP may have chronic gastritis
   2. Who has HP and what is associated with these types of gastric disease?
   1. A small number of patients that have HP develop PUD, however, patients that have PUD do not necessarily have HP
   2. HP has also been found in all patients that have duodenal ulcers (DU).
   3. Patients that have gastric ulcers (GU) caused by nonsteroidal anti-inflammatory drug (NSAID) may have HP (approximately 80%)
   3. There is an association between HP and adrenocarcinoma and lymphoma of the stomach, however, the rate is less than 1%
   4. Elimination of HP reduces the probability of an ulcer by with <10% occurrence the following year
2. The nuclear medicine procedure
1. HP produces an enzyme identified as urease that does not naturally occur in the human body but can be found in certain bacteria, fungi, algai, and plants
2. If ¹⁴C-Urea Breath Test - (UBT) is administered PO in the presense of urease hydrolysis ¹⁴C-UBT occurs converting it to ammonia and ¹⁴CO₂
3. The radioactive carbon is then captured during the exhaled breath at different time post ingestion, then analyzed via liquid scintillation (why do you think liquid scintillation has to be used?)
4. The presences of ¹⁴CO₂ indicates that HP is present

2. Procedure
   1. This test has been used in two different patient populations
      1. DU patients that have been treated for HP in order to confirm the elimination of the bacteria. This test should be done at least 1 month (or longer) after therapy or
      2. GU patients (non-NSAID) that have been initially diagnosed with HP or after anti-HP therapy
   2. Patient Prep - the following medications must be discontinued
      1. Antibiotics and Bismuth compounds (Pepto Bismol) for at least 30 days
      2. Sucralfate, proton-pump inhibitors, lansoprazole for two weeks
      3. Patient must be NPO 6 hours prior to the exam
   3. Dose
      1. 1.0 μCi of ¹⁴C-UBT (urea) capsule is administered with 20 mL of warm water
      2. Dose may be given in a format other than capsule, ARUP Laboratory uses a liquid form
      3. ¹⁴C
         1. Physical T_1/2 - 5730 yrs
         2. Beta Energy - 49 keV average/156 keV maximum
   4. Breath Collection
      1. Following initial administration 3 minutes post dose another 20 mL of warm water is consumed
      2. Ten minutes post dose patient holds his/her breath for 5-10 seconds and then exhales into a straw which is attached to a mylar bag. This process can be repeated 5 minutes later
3. Acquisition of data
   1. The scintillation vial contains l mmol hyamine, methanol and thymolphthalein in 2.5 mL of solution. From the mylar bag,containing the patient's CO₂ it is pipetted into the vial
   2. The goal is to capture 1 mmol of the patient's CO_2. .When the solution turns from blue to clear enough of the CO₂ has been captured. Then 10 mL of scintillation fluid is added to the vail mixed. For every sample collected the above process is repeated
   3. Standard (known amount of ¹⁴C) and Background (no ¹⁴C) vials are added to the beta counter - Concepts of standards and controls
   4. All samples are placed into a liquid scintillation counter and each vial is counted for 5 to 20 minutes
   5. Gross counters per vial is then subtracted by the background vial resulting in net counts. Net counts are then converted to dpm
   6. The efficiency of the counter is calculated by counting the activity in a known standard, subtracting its background, comparing it to the expected dpm of the vial. This ratio becomes the % efficiency. Efficiency and a known concentration (controls) of ¹⁴C are identified
4. Interpretation
   1. <50 dpm = Negative for HP
   2. 50 - 199 = Indeterminate for HP
   3. >200 = Positive for HP
   4. False negative results can occur when
      1. Antibiotics or bismuth administered within the last 30 days
      2. Sucralfate, proton pump inhibitors, or lansoprazole administered with the last 14 days
      3. <6 hours NPO
      4. Gastric surgery
      5. Difficultly in swallowing the pill - if this happens take 15 to 20 minute delay sample(s)
   5. False positive can occur when ..
      1. Gastric surgery with bacterial infection not related to HP
      2. Condition known as achlorhydria (when gastric acid is low or absent)

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Data for this lecture was attained from: Society of Nuclear medicine Procedure Guidelines For C-14 Urea Breath Test Balon H, Roff E., et. al. SNM 2002