In a low dose dexamethasone suppression test what values equal a positive test result?

This question is in relation to cushing's syndrome / disease, and I just got my low dose dexamethasone test results back, and like most who have a posibility of cushing's. doctors are sometimes unrelable. If anyone has or has had cushing's and understand the values in terms of a positive test result, please answer.
Answer:
Overnight test with 1 mg is kind of crappy, but it is still done because it is easy. If your serum cortisol the next morning falls between 1.2 to 14.3 mcg/dL (34-395 nmol/L), the test is inconclusive. If you're higher, you probably have Cushing's syndrome. If you're lower, you almost certainly don't.

The two-day 2 mg test is better, but is more inconvenient because you have to take the 0.5 mg doses at strict six-hour intervals for two days. For this, there isn't a huge equivocal region as there is for the overnight test. Here the cutoff is in the neighborhood of 1.8 mcg/dL or 50 nmol/L (plus or minus, depending on who you ask).

The important thing to remember about interpreting lab values is that these numbers are never absolute. "Normal" ranges typically include 95% of the normal population. In other words, 5% of the normal, healthy people out there will have "abnormal" lab results. The numbers have to be interpreted in the context of the whole patient. This is why the clinical judgment of your doctor becomes important.

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