Cushing Syndrome

Maybe Not So Uncommon of an Endocrine Disease

Federica Guaraldi, MD; Roberto Salvatori, MD


J Am Board Fam Med. 2012;25(2):199-208. 

In This Article

The Increasing Prevalence of Cushing Syndrome

There is little epidemiologic information about the incidence and prevalence of CS. It is traditionally estimated to affect 10 to 15 people per million population each year in the United States, which is the reason the Office of Rare Diseases of the National Institutes of Health (NIH) lists it as a "rare disease."[4] Studies conducted in Italy, Spain, and Denmark reported that the annual incidence ranges from 0.7 to 2.4 per million population each year.[5–7] Although the prevalence in the general population is reported to be a fraction of a percent, recent studies have suggested a much higher prevalence among high-risk patient populations, such as patients with diabetes mellitus (particularly if poorly controlled), hypertension, and early-onset osteoporosis (particularly if with fractures).[8–11] A study that screened 294 patients with type 2 diabetes mellitus and 189 age-, sex-, and BMI-matched controls by their ability to suppress cortisol determined that the prevalence of subclinical hypercortisolism was higher in diabetic individuals than in controls (9.4% vs 2.1%, respectively).[10] Interestingly, the patients' hypercortisolism was primarily from an adrenal origin. Two hundred patients with poorly controlled diabetes mellitus (HbA1C >8%) were screened for hypercortisolism and 5.5% were diagnosed with CS, mostly of adrenal origin.[9] In a study of patients with osteoporosis without clinically overt hypercortisolism, 4.8% of patients (11 of 219) had subclinical hypercortisolism and the prevalence was 10.8% if they also had a vertebral fracture.[11] Finally, among 1020 hypertensive patients, 21 (2.1%) had increased levels of cortisol.[12] These reports will need to be confirmed by larger studies in different regions of the world, and they certainly are affected by the entry selection criteria, but they provide a rationale to consider screening for CS even in patients who do not show all the signs of hypercortisolism. These results as a whole lead us to suspect that the real incidence of CS is higher than commonly believed. Nevertheless, the issue of increased screening is controversial, as exemplified in a recent review that argued the drawbacks of screening (cost, acceptability, and unnecessary procedures) may outweigh the benefits.[13]


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