Atypical Cushing's Syndrome in Dogs: Arguments For and Against

In the past 5 to 10 years, much interest has arisen in the syndrome of occult hyperadrenocorticism. Patients with occult hyperadrenocorticism purportedly have many clinical signs and routine laboratory abnormalities suggestive of the presence of typical hyperadrenocorticism, or Cushing's syndrome (ie, hypercortisolism either due to a pituitary or adrenal tumor). However, the standard diagnostic tests-corticotropin (ACTH) stimulation and low-dose dexamethasone suppression tests-are normal. A theory has arisen that the clinical signs of occult hyperadrenocorticism are due to excess adrenal secretion of sex hormones rather than cortisol. The authors believe that the role of sex hormones has not been proven. The article reviews the evidence both for and against the importance of sex hormones in creating occult hyperadrenocorticism.