Analyzing cortisol levels in hair close to the scalp may be a reliable diagnostic method for Cushing's syndrome.
Cushing's syndrome is a condition that occurs as a result of exposure to high levels of cortisol for an extended period. Elevated cortisol levels can be triggered as a side effect of corticosteroid medications that are used to treat inflammatory diseases, such as lupus, asthma, and rheumatoid arthritis.
Excessive cortisol levels can also be caused when a tumor develops inside one of the body's glands, such as the pituitary or adrenal glands, although this is less common. The adrenal glands produce cortisol. Cortisol helps control blood pressure and heart function and regulates blood sugar levels and the immune system.
Cushing's syndrome is relatively rare and diagnosing the condition is both difficult and time-consuming. If the condition is not treated and diagnosed early, it can be fatal.
Regular methods of diagnosis require several urine, blood, and saliva tests to be taken over 24 hours to measure for cortisol. Additionally, brain imaging tests and tissue samples from sinuses at the base of the skull may be analyzed. These examination methods can be challenging to conduct and inconclusive.
Hair analysis results compared with standard biochemical testing
As a solution, previous research has explored analysis of hair cortisol as a means to diagnose people with Cushing's syndrome. However, prior studies have not compared the levels of cortisol in standard blood and urine tests to cortisol in hair to validate hair analysis as a reliable diagnostic method.
National Institutes of Health (NIH) investigators examined the reliability of measuring hair cortisol levels to diagnose Cushing's syndrome by correlating data from hair analysis with data from standard biochemical testing.
Dr. Mihail Zilbermint, an endocrinologist at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), was the senior author of the study, and the results were published in Endocrine: International Journal of Basic and Clinical Endocrinology.
The team enrolled 30 participants with Cushing's syndrome and six patients who did not have the condition.
Compared with studies that look at more common disorders, the number of participants was small. Due to the rarity of the condition, it is difficult to recruit a large number of people. Nevertheless, the researchers say that this study is the largest of its kind to compare hair cortisol levels with diagnostic tests in people with Cushing's syndrome.
Hair samples close to the scalp, 3 centimeters in length, were taken from study participants. The hair was then divided into 1-centimeter segments and labeled with which section was closest, middle, and furthest from the scalp. Each segment was analyzed for cortisol and compared with laboratory testing.
Hair cortisol levels closely correlated with cortisol levels in urine, blood
Study findings showed that the cortisol levels in hair samples closely correlated with cortisol levels detected using standard techniques for diagnosing Cushing's syndrome.
Hair segments that were closest to the scalp contained the most cortisol. Compared with cortisol levels observed in the hair segment furthest from the scalp, the cortisol levels of the hair closest to the scalp more accurately matched with urine and blood cortisol results from tests conducted at night.
For most of the population, cortisol levels fall at night. However, people with Cushing's syndrome have elevated nighttime cortisol levels.
"Our results are encouraging. 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."
Dr. Zilbermint and colleagues note that further studies are needed to confirm their findings. The findings support further investigation into using 1 centimeter of hair closest to the scalp, and hair cortisol in general, as an initial or supportive diagnostic test for Cushing's syndrome, the authors conclude.