This version (2021/07/26 13:30) was approved by Graham Wright.This is an old revision of the document!
Table of Contents
Northern Lincolnshire and Goole NHS Foundation Trust - Nuclear Medicine
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| SOP Code | Title | Review Date |
|---|---|---|
| REF004 | SeHCAT | 2028-01-21 |
| Authorised By | Authorisation Signature (only on master paper copy) | Date Authorised |
|---|---|---|
| Prof G Avery | 2021-07-26 |
REF004 - SeHCAT
Purpose
The purpose of this document is to assist clinicians in deciding on the appropriateness of a Nuclear Medicine SeHCAT investigation for bile acid malabsorption and to give guidance on the mechanism of referral.
Background
Among the many causes of diarrhoea, malabsorption of bile acids can be a difficult condition to diagnose clinically. Furthermore, finding an acceptable treatment regime may be problematic, so that proof of the cause of the disease is important.
Malabsorption of bile acid can be investigated using Se75 labelled tauroselchoic acid (SeHCAT), which is an analogue of the naturally occurring bile acid conjugate taurocholic acid. In normal subjects, bile acids are produced and excreted into the duodenum by the hepatobiliary system and are reabsorbed by the distal ileum. If the functional integrity of the ileum is impaired, bile acids entering the colon reduce the reabsorption of water, resulting in chronic diarrhoea. Resection of a part of the bowel or Crohn's disease are common causes of bile acid malabsorption.
The SeHCAT investigation involves the measurement of the seven day retention of an oral dose of the radiopharmaceutical and is a useful test in the investigation of diarrhoea of unknown origin. NICE SeHCAT Guidance[1] grades the severity of the bile acid malabsorption as follows:
- retention values of 10–15% (mild bile acid malabsorption)
- retention values of 5–10% (moderate bile acid malabsorption)
- retention values of 0–5% (severe bile acid malabsorption).
| ARSAC Licence Holders |
|---|
| Prof Ged Avery |
| Dr Najeeb Ahmed |
| Nuclide | Pharmaceutical Form | Local DRL (MBq) |
|---|---|---|
| Se75 | SeHCAT | 0.37 (Acceptable Range: 0.25-0.44) |
| Typical Radiation Dose (mSv) | 0.3 |
|---|
Staff Permitted to Refer
- Any clinician holding a current valid medical qualification currently employed in Secondary care.
Referring clinicians are reminded of the requirement to avoid unnecessary exposure to ionising radiation. The investigation may already have been requested at this hospital or elsewhere and clinicians are asked to be particularly vigilant to ensure that their request is not a double request.
Acceptance of Referrals
Requests will only be accepted if the diagnostic question fulfills one of the referral criteria below. Appropriate clinical information must be supplied to allow the investigation to be justified. It is not acceptable to simply request the investigation without appropriate clinical information.
Requests will be returned to the referrer if:
- The diagnostic question is unclear.
- The diagnostic question cannot be answered by the investigation.
- Insufficient clinical information is supplied to justify the investigation.
Requests should be submitted on the orange stripe NUCLEAR MEDICINE (ISOTOPE SCAN) request form. Patient details, Investigation required and Reason for Test/Diagnostic Question should be fully and appropriately completed and the form signed.
Referral Criteria
Sufficient clinical information must be provided to justify the investigation proceeding.This includes ensuring that first line investigations have been performed in the correct place in the clinical pathway, e.g. colonoscopy and fecal calprotectin testing.
The clinical indications are detailed below.
| Investigation |
|---|
| Investigation of suspected bile acid malabsorption |
| Investigation of the cause of diarrhoea of unknown origin |
| Investigation of the cause of diarrhoea following surgery to resect a part of the bowel |
| Investigation of the cause of diarrhoea following radiotherapy to the lower abdomen |
| Assessment of ileal involvement in inflammatory bowel disease e.g.Crohn's |
Contraindications
| Mobility | Due to the configuration of the current gamma cameras, the patient must be able to lie down on the floor for acquisition of the count data. |
|---|---|
| Medical Conditions | SeHCAT is not indicated when terminal ileum has been resected[1] |
Patient Preparation
| Recent Investigations | Please indicate clearly on the request form any diagnostic Nuclear Medicine procedures in the previous 2 months or any therapeutic Nuclear Medicine procedures in the previous 6 months |
|---|---|
| Medication | Patients attending for first SeHCAT study Abstain if possible from bile acid sequestrants, such as Questran (colestyramine), Colesevelam or Colestipol, and anti-diarrhoeals from the day of the capsule administration until after the final images at day 7. Patients attending for a follow-up SeHCAT study If the patient is taking bile acid sequestrants such as Questran (colestyramine), Colesevelam or Colestipol, please indicate if these should be stopped. Abstain if possible from anti-diarrhoeals from the day of the capsule administration until after the final images at day 7. |
| Diet | Fast for 4 hours prior to the first appointment time[2]. Diabetic patients do not need to fast but should only have a light breakfast. |
