Test Category: Specialist Biochemistry
Investigation Name:7α-hydroxy-4-cholesten-3-one (7aC4)
Alias or Abbreviation:7aC4
Intro:
7α-hydroxy-4-cholesten-3-one (7aC4) is a biomarker used in the investigation of Bile Acid Diarrhoea (BAD).Although BAD affects between 1% and 5% of the population, many individuals remain undiagnosed due to the limited availability of routine diagnostic tests. According to the British Society of Gastroenterology (BSG) 2023 guidelines for investigating chronic diarrhoea, diagnosis can be made using either 75SeHCAT testing or 7aC4 measurement.
75SeHCAT testing has several limitations, including restricted access to scanning facilities, supply chain issues with SeHCAT capsules, high costs, the need for multiple hospital visits, and exposure to radiation.
In contrast, 7aC4 is a bile acid precursor that becomes elevated in cases of bile acid malabsorption and can be measured with a single blood test, making it a more accessible option.
To ensure accurate results, blood samples should be taken while fasting, ideally between 8:00 and 10:00 AM, due to the influence of circadian rhythms. Additionally, factors such as statin use, alcohol consumption, and high triglyceride levels may also affect 7aC4 levels.
Pathology Laboratory:Mass Spec Laboratory
Requestable Seperately?Yes
Minimum Sample Volume:Preferred: 500 µL serum
Absolute minimum: 150 µL
Expected Turnaround Time:14 days
Test Code:7AC4
Sample Type:
SerumComplex Reference Range:<50 nmol/L: Bile Acid Diarrhoea unlikely. Consider other causes of chronic diarrhoea
50-131 nmol/L: Result in indeterminate range. Consider further investigations, such as SeHCAT
>131 nmol/L: Bile Acid Diarrhoea likely. Consider trial of bile acid sequestrants
Collection Conditions / Other Information:• Whole blood samples are stable for up to 24 hours at ambient temperatures.
• Separate serum and aliquot as soon as possible after receipt.
• Serum is stable for 8 days at 4°C or at least 14 days at -20°C
• Samples may be transported at ambient temperatures (up to 37°C) if delivery to the laboratory is guaranteed within 24 hours.
• Use temperature-controlled transport if delivery within 24 hours cannot be guaranteed.
• If samples are frozen in your laboratory, please send frozen on temperature-controlled transport as stability has not yet been established beyond a single freeze-thaw cycle.
Referred to Another Laboratory?No
Storage Requirements:• Store samples at 4°C if analysis will be performed within 7 days.
• Store samples at -20°C for up to 14 days if longer storage is required. Samples are likely to remain stable at -20 although there is currently no evidence to support or refute this.
• If samples are received frozen, maintain the frozen state when received and store at -20°C.
• If samples are received thawed following freezing, store at 4°C and analyse within 7 days.
• Avoid repeated freeze-thaw cycles, as stability has not yet been established beyond a single cycle.
Posting Address / Requirements:Sandwell Health Campus
Specialist Chemistry,
Pathology Department,
Lyndon,
B71 4HJ
NPEX / PDF Reporting Available:NPEX and PDF reporting available.
Lead Contact Details:Helen Duce, Principal Clinical Scientist
Email: h.duce@nhs.net
Email Address For Chasing Results:rwh-tr.bcpsspecialistchemistryenquiries@nhs.net
Methodology:Liquid chromatography-tandem mass spectrometry
Site Sample Tested:Sandwell Health Campus
Cost:Please email: bcpspathology.info@nhs.net for further details
Contact Number:Tel: 0121 507 5162
