Diagnosing Cushing’s syndrome can take 24 hours of complicated and repeated analysis of blood and urine, brain imaging, and tissue samples from sinuses. But that may soon be in the past: National Institutes of Health (NIH) researchers have found that measuring cortisol levels in hair samples can do the same job faster.
Patients with Cushing’s syndrome have a high level of cortisol, perhaps from a tumor of the pituitary or adrenal glands, or as a side effect from medications. In the study, 36 participants—30 with Cushing’s syndrome, six without—provided hair samples divided into three equal segments. The researchers found that the segments closest to the scalp had the most cortisol (96.6 ± 267.7 pg/mg for Cushing’s syndrome patients versus 14.1 ± 9.2 pg/mg in control patients). Those segments’ cortisol content correlated most closely with the majority of the initial biochemical tests, including in blood taken at night (when cortisol levels normally drop).
The study was small; Cushing’s syndrome is rare, and it’s hard to recruit large numbers of patients. Still, the researchers believe it is the largest of its kind to compare hair cortisol levels to diagnostic tests in Cushing’s patients. “Our results are encouraging,” said Mihail Zilbermint, MD, the study’s senior author and an endocrinologist at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development. “We are hopeful that hair analysis may ultimately prove useful as a less-invasive screening test for Cushing’s syndrome or in helping to confirm the diagnosis.” The authors suggest the test is also a convenient alternative with the “unique ability” for retrospective evaluation of hypercortisolemia over months.