In the US JenCG is right they use the ACTH stim test.
The Anterior lobe of the pituitary gland ACTH acts through the stimulation of the cell surface ACTH receptors...the cortex of the adrenal gland and boosts cortiosteriods. Or cortisol hormone is produced by the adrenal cortex in the adrenal glands.

The amount of cortisol present in the serum undergoes diurnal variation, with highest levels present in early morning and the lowest levels at midnight or 3-5 hours after on set of sleep. Low cortisol causes sleep disorders, hypoglycemia, weakened immune system, lowers b one density, memory problems, vasodilation, low BP, vitiligo, headaches, muscle weakness, and fatitque.

I read in a book America Fatiqued that usually they do 3 tests:
1 - a 24-hour urine analysis before and after administration of ACTH. This will tell them how your adrenals are functioning at restand will give them an idea what happens when they are stimulated.

2- Blood Testing is the most common test used and is usually done before and after ACTH. The doctor evaluated the cortisone levels before , and then at one-half, and one hour after the ACTH injection. Thhis test can be very useful if it is evaluated right. However, some patients with CFS who show abnormal adrenal fatique on 24 hour urine test have what appears to be normal pre/post ACTH stimulation of the blood. The blood test therefore misses many people with adrenal fatique cause they appear to be able to mount a normal stress response for a very short term, after that they decompensate quickly.

3- Saliva Testing-
This is an easy way to evaluate fluctuations in cortisone levels. It has been helpful in determining if the cortisones are elevated or decompressed at inappropriate times of the day.

These tests revealed that CFS patients have what they called or was described as permanant jet-lag. this means that there cortisones were being produced at inappropriate times for their lifestyle. Their cortisones were going up at 11:00 pm, at a time when the cortisones should be starting to decrease. By 2:00 am ususally our cortisones are the lowest of the day. Their cortisones were down in the mornings. This is the time when our cortisones should be the highest of the day.

This is why many CFS patients have abnormal sleep/wake cycles.

They said the best test is the 24 hour urine test for CFS.

Hey Wolfgangm
I would get the doc to order a 24-hour urine - it is supposed to be the best test for CFS patients with adrenal insufficiency.

With the EBV I am only familiar with the test that measures high titers of the EBV (lab tests measure titers, or concentrations of anitbodies, to determine the amount of EBV in the body.) Mine showed elevated levels. I will see if I can figure out what test that is.

Have a Nitric Oxide breath test using a NIOXmino machine can validate a high NO?ONOO level.
http://www.nioxmino.com/
and
http://molecular.biosciences.wsu.edu/faculty/old%20files/pall/pall_main.htm

Undergo tilt table testing or if your GP knows how to do the 20 minute standing "Change in Pulse Pressure, Change in heart rate test" and compare it to the norms for recumbant and standing measurments for healthy people then it can help validate CFS readings.
Orthostatic systolic hypotension: fall in systolic blood pressure of 20 mm Hg or more.
Orthostatic diastolic hypotension: fall in diastolic BP of 10 mm Hg or more.
Orthostatic diastolic hypertension: rise in diastolic BP to 98 mm Hg or higher.
Orthostatic narrowing of pulse pressure: fall in pulse pressure to 18 mm Hg or lower.
Orthostatic postural tachycardia: increase in heart rate of 28 bpm or to greater than 110 b/min.
Normal responses of pulse and blood pressure to prolonged standing are as follows:

Normal systolic BP: recumbent: 100-142; Standing (4 min): 94-141; Orthostatic change: -19 to +11
Normal diastolic BP: recumbent: 55-90; Standing : 61-97; Orthostatic change: -9 to +22
Normal Pulse: recumbent: 54-96; Standing : 62-108; Orthostatic change: -6 to +27.
Refer;
http://www.pediatricnetwork.org/medical/CFS/bell-commentary/nmh-cfs.htm

Have your citric acid cycle analysed.
Have your 24 hour 'ACTH stim test' analysed.
Have a Blood test to asses your viral loads (specifiaclly the one that ID's the viruses, not just the one that sais your antibodies (IgG or IgM) cant remember which) are high.

Read
http://www.immunesupport.com/library/showarticle.cfm/ID/6104/T/CFIDS_FM/searchtext/Epstein

Below are some quotes from the article.

According to Dr. Bob Sears, a pediatrician in San Clemente, Calif., and co-author of The Baby Book, the chicken pox virus is very persistent. "It never completely leaves the body," he explained. "Varicella-zoster remains dormant in the nerves, and for most people, it is dormant forever."

Chickenpox isn't the only disease that has a nasty habit of coming back to haunt you. Mononucleosis -- or "mono" -- is another. Mono is a fairly common acute illness in children and young adults caused by the Epstein-Barr virus (EBV), said Sears. EBV infection initially causes fever, a rash and sore throat, accompanied by fatigue that can last several months.