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 | Authorising Role | Authorisation Signature (only on master paper copy) | Date Authorised |
|---|---|---|---|
| Prof G Avery | ARSAC Licence Holder | 2025-01-21 |
See REF000 - Referring to Nuclear Medicine (NLAG) for details on how to refer.
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] recommends that a threshold of 15% retention of SeHCAT should be used to define a positive test result.
| 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 |
|---|
| 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] |
| 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. |
| 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 |