Adult Pilot Study for Reference Ranges and Optimal Cut-offs for the Sucrose Challenge Test and Sucrose Breath Test

In an effort to mimic the real-world diagnostic setting for these tests, this study will be conducted virtually using a central site with telemedicine capabilities and electronic data capture software to collect data in real time via a mobile app. Subject will complete 3 visits within 21 days. Eligible subjects will undergo the following tests:

• 50g 13C-Sucrose Breath Test (CBT)
• Sucrose Intolerance Hydrogen Methane Breath Test (HBT)
• Sucrose Challenge Test (SCT)
• Buccal swab for CSID Genetic Testing (GT)

The primary aim is to establish the reference/normal ranges and optimal cutoff values for the SCT and CBT.

Inclusion criteria

• Subject must provide informed consent prior to any study procedures being performed.
• Subject is a U.S. resident, and speaks and understands English
• Subject is male or female, ≥ 18 years old.
• CSID Cases must have been on Sucraid for at the last 12 months.
• Healthy Volunteers do not have a CSID diagnosis or other chronic gastrointestinal conditions.
• Subject must have their own Android or Apple device to access the mobile patient app.

Exclusion criteria

• Females who are lactating or pregnant.
• Subjects with allergy to sucrose.
• Subjects with causes of abdominal pain or altered bowel habits other than symptoms -related to CSID (in CSID group) such as SIBO, IBD, celiac disease, pancreatitis, or -gastrointestinal bleeding.
• Diabetes mellitus.
• Use of systemic antibiotics, had a barium study, colonoscopy, unexplained runny diarrhea, or similar within 14 days prior to informed consent. Potential subjects can be re-screened once they meet this criterion.
• Recent febrile illness.
• Subject has major physical or psychiatric illness within the last 6 months that in the opinion of the investigator would affect the subject's ability to complete the trial.