Advice re short synacthen test

[blackqueen65]

I'm due to have a short synacthen test on Thursday, does anyone know if I need to fast beforehand and whether I should still take my Levothyroxine, or anything else I should do? Thanks in advance for any tips.

Shaz

[Moggie]

You just do everything as normal - no need to fast and no need to stop taking levo.

It's a very painless procedure and only takes a couple of hours. I was able to drink as much tea as I wanted and was even offered biscuits.

In other words, there is nothing to worry about at all.

Good luck

Moggie x

[blackqueen65 in reply to Moggie]

Thanks Moggie

[Lynn27]

I got one two weeks today. Iv been told not to take my morning meds!!!! Feed back please!!! Thanks

[bantam12]

I was told to do everything as normal, no need to fast or stop meds.

[blackqueen65 in reply to bantam12]

Thanks hypohen

[Glynisrose]

Just make sure you get your test early in the morning, it makes a huge difference what time of day you have the test.

[blackqueen65 in reply to Glynisrose]

Thanks Glynisrose, my test is 8.30am so hopefully will be ok.

[Moggie]

Just to clear things up this is from The Endocrinologist Handbook and surprisingly it does say that you must not take estrogen (the pill or HRT) and statins - which I was never told about (not that I am on either but some on here might be)

SHORT SYNACTHEN TEST

INDICATION

Used in the diagnosis of hypoadrenalism as a screening test.

It is an increasingly used alternative to the insulin tolerance test to diagnose secondary hypoadrenalism due to pituitary hypofunction. However, it should not be used in the early post-operative assessment of the hypothalamic-pituitary-adrenal axis (an insulin tolerance/glucagon stress test should be used instead).

May also be used to ascertain that the adrenals are functioning normally after a prolonged course of corticosteroids, or after suppression by Cushing’s syndrome (e.g. after removal of a unilateral Cushing’s adrenal adenoma).

Diagnosis and characterisation of 21-hydroxylase deficiency and other causes of adrenal hyperplasia.

Diagnosis of non-classical congenital adrenal hyperplasia in the context of a hyperandrogenic woman, if the morning follicular-phase baseline 17-hydroxyprogesterone is >6.0 nmol/l.

CONTRAINDICATIONS

Definitely not required for assessment of hypoadrenalism if random cortisol > 550nmol/l.

If a random cortisol >450, patients are very likely to pass the test, and some feel that in this circumstance, the test is not usually warranted.

SIDE EFFECTS

None

PREPARATION

If on steroids ensure that none is taken the night prior to the test or on the morning of the test. The final dose of hydrocortisone should be at midday, on the day prior to the test.

HRT or any oestrogen should be discontinued for 6 weeks before the test.

In patients in whom the test is being used to screen for 21 hydroxylase deficiency, the test should be done in the follicular phase because progesterone levels rise substantially in the luteal phase, and there is some cross reaction between the 17 OHP assay and the Progesterone assay.

Admission is required if there is a risk of Addisonian crisis (virtually never).

18-20g cannula

Saline flush

10ml syringes x 4

3 red top Vacutainers for cortisol (same samples for 17-OH progesterone)

1 EDTA tube (purple top Vacutainer) for ACTH basal sample.

1 ampoule of 250 micrograms tetracosactrin (Synacthen)

METHOD

1. 0900h: take 7 ml blood for cortisol (red top Vacutainer) and ACTH (purple top, on ice to lab immediately).

2. Give 250micrograms tetracosactrin IM (ideally) or IV.

3. 0930h: Take 7 ml blood for cortisol.

4. 1000h: Take 7 ml blood for cortisol.

5. For the diagnosis of congenital adrenal hyperplasia the samples taken for cortisol are also analysed for 17-OH progesterone to exclude 21-hydroxylase deficiency. In some cases 17-OH pregnenolone is measured to differentiate between 21-OH and 3ß-HSD deficiency.

INTERPRETATION

Normal response if test done at 0900h (considerable diurnal variation):

Stimulated plasma cortisol >550 nmol/l

Incremental rise of at least 170 nmol/l

· If impaired cortisol response, and ACTH >200 ng/l then diagnosis is primary adrenal failure.

· If ACTH <10ng/l then diagnosis is secondary adrenal failure

· Response of 17-OH progesterone in suspected 21-hydroxylase deficiency (non-classical): marked rise after ACTH stimulation (>30 nmol/l), which varies according to whether the patient is homozygous or heterozygous. Reference for nomogram: New et al., JCEM 57, 320-326 (1983).

SENSITIVITY AND SPECIFICITY

A normal cortisol response does not exclude adrenal failure, since impending adrenal failure might be associated with a much greater loss of zona glomerulosa function. The latter would be suggested by an elevated plasma renin activity.

If equivocal result and no urgency, repeat test after a few weeks.

An abnormal response is consistent with primary or secondary adrenal failure, and should be investigated further. Consider long synacthen test or pituitary function testing.

Hope I haven't confused the issue more.

Moggie x

[blackqueen65 in reply to Moggie]

Thanks Moggie, I'm not expecting anything to come of it really but just happy to have it ruled out.