Saturday, July 25, 2009

Cushing's or Syndrome X?

Q. I am a third-year medical student doing a rotation in endocrinology. A patient I saw recently has type 2 diabetes, absence of menses, high cholesterol, hypothyroid, hypertension and obesity (especially in the upper body). She was tested for Cushing's, which showed a slightly elevated level of cortisol, but it was within normal range. Is it possible to have Cushing's if the level is still within normal range? What are other indicators of this disease? Are there other diagnoses to consider?


A.There are two parts to the diagnosis of Cushing's syndrome: an increased cortisol production and a failure to suppress endogenous cortisol secretion when dexamethasone is administered. Indicators appear in the physical examination (muscle weakness, cutaneous striae, bruising, moon facies, buffalo hump, truncal obesity) and the lab (osteoporosis, hypokalemia, hypochloremia, metabolic alkalosis). Since your patient has a normal cortisol level, however, Cushing's would be extremely unlikely.

Whenever you are confronted with a patient with multiple problems, it is nice to find a single diagnosis to explain all the findings. This will not usually happen, though. In this case many possible combinations of diseases might be suggested. For example, the diabetes, hypercholesterolemia, hypertension and obesity mean the patient might have Syndrome X. Also, hypothyroidism is often associated with amenorrhea. So it may be the patient has two problems (hypothyroidism and Syndrome X) instead of one (Cushing's). As you can see, there are many other possible combinations.