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How to screen for Cushings syndrome?

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Practicing since : 2001
Answered : 1663 Questions
Does this blood test result require further investigation? Serum Cortisol was 686 nmol/L Range 138 - 690 As you can see it is on the high side of the range right at the top, but still falls within range. However, I have seen on other places online the top range, MAXIMUM is around 500-660, which would show me to be quite far out of range. Also the sample was taken at 10am when I hear Cortisol is at it's highest at 7-8am so this result is already not at it's peak which concerns me even more. I'm Male and 18, not felt well for around a year currently diagnosed with chronic fatigue syndrome with mild hypothyroidism although i'm taking levothyroxine for this at them moment. Could mild cushings syndrome be my problem? I have had weight gain for the past 2 years even though I eat right, very poor immune system, don't heal very quickly and bruise easily.
Posted Wed, 19 Feb 2014 in Thyroid Problem and Hormonal Problems
Answered by Dr. Shehzad Topiwala 3 hours later
Brief Answer: Cushings syndrome Detailed Answer: A morning blood test for cortisol is not the correct way to check for the presence of Cushings syndrome. The recommended way is to screen using one of three tests, or a combination of them if the index of suspicion is high. The three tests are 1) 1 mg overnight dexamethasone suppression test. In this test, a 1 mg tablet of dexamethasone is taken close to midnight and a blood sample for cortisol is taken at 8 am the next morning. This is assuming you have normal sleep wake cycle like most people and do not work night shifts 2) Checking for cortisol levels in the saliva close to midnight 3) 24 hour urinary collection for cortisol. So the random blood cortisol test and the values you have shared above are not worth interpreting in the context of trying to ascertain a diagnosis of Cushings syndrome. I have noted your symptoms and advise you to see an Endocrinologist in person because they are the only physicians truly qualified and trained to interpret complex hormone tests.
Above answer was peer-reviewed by
Follow-up: How to screen for Cushings syndrome? 10 hours later
I know this test is not a diagnosis I just had it done to check my baseline levels. Is a test this high in the morning likely to mean that I still have high levels at night?
Answered by Dr. Shehzad Topiwala 3 hours later
Brief Answer: Follow up Detailed Answer: High levels in the morning do not necessarily mean they persist to stay high at night. The only value of a morning cortisol blood test is to rule out the possibility of adrenal insufficiency. It is of little or no value to diagnose Cushings syndrome.For this condition there are several other tests, 3 of which I have described above
Above answer was peer-reviewed by
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