Not saliva - not sure how easy this is to do in the UK? I had something called 'BEST' testing done which measures skin electrical conductivity and compares values to base data - its used predominatly for food allergies etc - but i had the hormonal profile run also and was tested below norm for adrenaline and testosterone (I'm female). Also, was low in minerals generally recommended for rebuilding adrenals such as magnesium.
I self diagnosed adrenal fatigue based on my symptoms and the above and have had some success by supplementing w vits and mins and with IsoCort.
In addition I go to acupuncture and physio for my lower back - I have some structural problems which in fact might have been a contributing factor to the adrenal fatigue...