Tuesday, 19 August 2014

DIARY - BAM & the SeHCAT Test

If you've read any of my recent posts you'll know I've been complaining about having to rush off to the bathroom rather more frequently than I would expect for someone in "clinical remission" from Crohn's. To combat this problem I have been taking a couple of Loperamide (Imodium) capsules a day and then an extra one if I'm expecting to be "away from civilisation" (ie. a decent loo) for a long period.

I've mentioned this to my consultant a few times and he did say there is an alternative to Loperamide that might be worth trying - a bile acid sequestrant. I didn't really take it in but at my last appointment in June he said he thought it would be a good idea for me to have a SeHCAT test to see if I had a problem with bile acid malabsorption.  Here's how Wikipedia explains it :

"SeHCAT is a taurine-conjugated bile acid analog which was synthesized for use as a radiopharmaceutical to investigate in vivo the enterohepatic circulation of bile salts. By incorporating the gamma-emitter Se into the SeHCAT molecule, the retention in the body or the loss of this compound into the faeces could be studied easily using a standard gamma camera, available in most clinical nuclear medicine departments."

The SeHCAT Test

As tests go this must be one of the least stressful that there is, unless you have problems swallowing pills that is. The procedure required three visits to the Department of Nuclear Medecine at St.Thomas' Hospital.
The hottest day in London so far. View from Hungerford Bridge
Tuesday 29th July 2014 - First visit - It was the hottest day of the year so far in London. I didn't want to catch the Tube so decided to walk from Holborn down to St.Thomas' Hospital (opposite the Houses of Parliament). Having made my way through the throngs of tourists on the Embankment and arrived just before my allotted time, 12:30pm, and after a short wait was taken into a side room. A container was produced and opened. It clearly was some type of radioactive shielding and inside it was a single capsule, the same size as my Loperamide tablets. I was given a glass of water and told to swallow the pill. First part over.

The salts in the capsule needed time to dissolve and pass into the gut so I was told to return at 3:30pm. I retraced my steps back to Holborn.
St.Thomas' from Westminster Bridge
Later on Tuesday 29th July 2014 - Second Visit - Walk from Holborn No.2. I arrived exactly at 3:30pm. Luckily there were slightly smaller crowds of tourists to contend with otherwise I would have been late. As soon as I arrived I was shown to another waiting area whilst the x-ray machine was prepared. After a few minutes I was taken into the scanning room and asked to lay on the sliding table, face up. The radiographer lined up the x-ray head and then I just had to lay there for 5 minutes. I was then asked to roll over onto my front and had another 5 minute scan. When the scan was complete I was told to come back the same time next week for the follow-up.

That was all there was to it and I was shortly on my way to Victoria station to catch the train home. When I checked the Moves app on my phone that night I had walked 16.8km, an all time record and in that heat.
X-Ray Machine in Dept. of Nuclear Medecine

Tuesday 5th August 2014 - Third Visit - Another walk down to St.Thomas'. When I arrived they were waiting for me. As soon as the x-ray machine had been prepared I had the two, five minute scans and the test was complete. A computer then compares the two sets of scans and works out how much of the bile acid is retained in the body. Results would take a week to come through.

The Results - I left it a week and then emailed my consultant to ask if the results were available. I quickly got a response in which he had pasted the conclusion of the report :

"SeHCAT Retention at Day 7=1% (Normal study: greater than 15%)
 Impression: Severe Bile acid malabsorption"

He gave me the option of making an appointment to discuss them with him or he could write to my GP to start some treatment, or could do both. I opted for "both". The appointment has come through for end of September. Given that the malabsorption is described as "severe" I'm surprised I don't feel a lot worse. I've held off doing any research into BAM as I was hoping that the test might prove negative.

Research - Time to find out a bit more about the subject. I typed "Bile Acid Malabsorption" into Google and started working my way the suggested sites. After scanning through several pages worth of links I came away with three overall impressions :
  1. BAM is often overlooked as a diagnosis of diarrohea
  2. The SeHCAT test is not widely used in the UK and is not even licensed in the US
  3. Of the meds available to treat BAM, two are in powder form and a new tablet form. The powder form is not well tolerated by patients and this leads to a high rate of non-adherence
 The last point was reinforced by a couple of questions of Crohn's forums. The meds are not very nice to take. The tablets are better but more expensive so not so popular with doctors.

Next Steps - The consultant is going to write to my GP with the findings of the test. I have a follow-up appointment at St.Thomas' organised for the end of September. I don't want to start on any new medication until we've had a discussion that appointment. In the meantime I'll continue to manage the condition with Loperamide as required.

The big question I will want answered is "given that bile acid sequestrants are not very pleasant to take, am I better of sticking with the Loperamide or are the disbenefits outweighed by the advantages of not having so much bile acid passing into the gut". Watch this space or follow this link "Let's talk BAM amongst other things".

NICE - One of the documents I came across was a NICE publication entitled "SeHCAT Testing for the investigation of diarrhoea due to bile acid malabsorption". It's not a document about BAM itself but a study into the cost effectiveness of the SeHCAT test as a diagnosis tool. (The link is at the bottom of this page). It sets out the evidence that they considered, including some background information and statistics.

To save you having to wade through the 30 or so pages these are the sentences that took my eye :

3.11 - "IBS most commonly presents for the first time between the ages of 20 and 30 years and is twice as common in women as in men. People with IBS are the largest group of patients seen in general gastroenterology clinics (1 in 20 referrals). The prevalence of the condition in the general population is estimated to be between 10% and 20%."

3.13 - "Crohn’s disease is estimated to affect about 60,000 people in the UK, around 100 per 100,000 population."

3.14 - "Crohn’s disease is sometimes treated by ileal resection. The prevalence of bile acid malabsorption among people with Crohn’s disease in clinical remission who have had ileal resection is high (97%)"

5.23 - "For the population with Crohn’s disease, no reports were found that suggested the chronic diarrhoea caused by the condition leads to excess mortality. However, people with Crohn’s disease have a shorter life expectancy compared with the general population."

6.11 - "The Committee acknowledged that people with chronic diarrhoea are likely to be classified as having a disability and therefore be protected under the Equality Act 2010."

NICE Document - SeHCAT Testing