Cortisol levels in hair correlated strongly with standard tests
by Jeff Minerd
Contributing Writer, MedPage Today
Analyzing the levels of cortisol in hair may aid in the diagnosis of Cushing syndrome, perhaps one day replacing invasive blood tests, scientists said.
Cortisol levels in the proximal ends of hair samples taken from patients with the syndrome correlated strongly with blood tests (R=0.4; P=0.03) and urine tests (R=0.5; P=0.005) for cortisol, reported Mihail Zilbermint, MD, of the National Institute of Child Health and Human Development in Bethesda, Md., and colleagues.
“The diagnosis of Cushing syndrome is often challenging and inconclusive, despite numerous tests used for the detection of hypercortisolemia and its origin, and is associated with high morbidity and high risk for mortality, if undiagnosed and untreated,” Zilbermint and colleagues wrote online in Endocrine: International Journal of Basic and Clinical Endocrinology.
“As a potential solution to the limitations of these tests, hair cortisol has been increasingly studied as an additional means to diagnose patients with Cushing Syndrome. Much like hemoglobin A1C is a longitudinal marker of blood glucose levels, hair cortisol can be a measure of the body’s glucocorticoid levels over the previous several weeks to months.”
“Our results are encouraging,” Zilbermint said in a statement. “We are hopeful that hair analysis may ultimately prove useful as a less-invasive screening test for Cushing syndrome or in helping to confirm the diagnosis.”
The study included 30 patients with Cushing syndrome and six control individuals without the disease. The participants’ average age was 26, and 75% were female and 75% were Caucasian.
The investigators took 3 cm-long hair samples from all patients, analyzed the proximal, medial, and distal segments of the samples for cortisol, and compared the results with results of standard blood and urine tests. Cortisol levels were highest in the proximal segments and correlated best with the standard tests, the investigators reported.
“We found that proximal hair cortisol directly correlates with late night serum cortisol and UFC [urinary free cortisol] in patients with and without Cushing syndrome. The most proximal 1 cm of hair was the best section of hair for stratifying the two groups of patients in our cohort.
“These findings support further research on the use of this modality in the workup for Cushing syndrome.”
Regarding the study’s limitations, the team pointed to the small control group of only six patients. Another limitation is that more than half of the participants (58%) were younger than age 18, and pubertal status on cortisol metabolism may be a factor in hair cortisol measurement.
“However, our study’s strengths are that it is the largest sample so far to analyze segmental hair cortisol in Cushing syndrome, and that it is the largest study to compare hair cortisol to any biochemical test for hypercortisolemia in patients with Cushing syndrome,” Zilbermint and colleagues said. “Our study also included a large cohort of Cushing Disease patients, which has been under-represented in prior studies on hair cortisol.”
The study was funded by the National Institutes of Health. Zilbermint and colleagues reported having no relevant financial relationships with industry.
Filed under: Cushing's, Diagnostic Testing | Tagged: 24-hour urinary free cortisol, blood tests, cortisol, Cushing's Syndrome, hair, Morbidity, mortality, National Institute of Child Health and Human Development, NIH, salivary cortisol, UFC | 2 Comments »