The Short Synacthen Test

A couple of weeks ago, I had a repeat Short Synacthen Test. A few people have asked what it involved, but I probably wasn’t very good at explaining it verbally, so I thought I’d write about my experience of it.

What is a Short Synacthen Test?

It tests adrenal gland production of cortisol and helps diagnose Primary (Addison’s Disease) or Secondary Adrenal Insufficiency. It can also check for other things, but not in my case. Cortisol is a hormone, and plays a part in pretty much everything: from how you respond in a stressful situation (fight or flight) to digesting your food. You need it to survive.


What does the test involve?

The Short Synacthen Test lasts about an hour. A baseline blood test is taken first, followed by an injection of synthetic ACTH. After 30 minutes, another blood sample is taken, followed by a final blood sample at 60 minutes. You have to go to hospital on the day of the test, usually first thing in the morning (although before 11am is fine), and are supervised by an endocrine nurse for the time you’re there. Once it’s over, you can go home and resume normal routine.

How does it work?

The pituitary gland is responsible for sending ACTH (another hormone) to the adrenal gland, telling it to make cortisol. The injection mimics this. A normal response would be that cortisol production would increase between the baseline and 30 minute blood sample, and increase further between the 30 minute and 60 minute sample. In someone who has Adrenal Insufficiency, the cortisol level would not move at all or would move very little.

What preparation do you have to do beforehand?

The test won’t be accurate if steroids are taken prior to the test, as it would show a higher level of cortisol in the blood. This means I had to stop some of my medications beforehand- I had to stop taking my steroid inhaler for 3 days and my Hydrocortisone for 24 hours prior to the test.

I found this a scary prospect. I’ve been on my inhaler for 12 years and have been on some kind of steroid tablet consistently for 2 years. It wouldn’t be safe for me to maintain normal activities during this period, so I didn’t leave the house for the 3 days when I wasn’t taking my inhaler and made sure I had a friend to help me for the 24 hours before the test while my husband was at work.

What does the test feel like?

The test itself was fine- the injection makes your arm feel stiff and the blood draws are just the normal ‘sharp scratches’ you have with any other blood test. Some people feel ‘better’ after the injection, but I felt no different. The day before, once I’d stopped Hydrocortisone, I felt more tired, sick, dizzy and foggy than usual, but it wasn’t anywhere near as bad as I was expecting. However, I was expecting to feel ‘ok again’ once I’d started my Hydrocortisone at midday after the test. This wasn’t the case and I slept for the rest of the afternoon, and really struggled with my mood and maintaining normal activities for the days after the test. It took about a week for me to feel back to normal.

What do the results show?

The test was to determine if my production of cortisol had improved. The results came back saying I’m still not making any/enough cortisol myself to survive, so my treatment plan is still the same as before the test.




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