High Morning Cortisol & Cushing’s Disease: Is It Cushing’s? | Good Hormone Health
The answer is no for 3 reasons:
First of all, I did a study when I was at the NIH about 30 years ago showing that people with Cushing’s syndrome and those tested for Cushing’s syndrome and not having it, have similar morning cortisol [Friedman, T.C. and Yanovski, J.A. (1995) Morning Plasma Free Cortisol: Inability to Distinguish Patients with Mild Cushing Syndrome from Patients with Pseudo-Cushing States. J. Endocrinol. Invest. 18:696-701. PMID: 8719300].
Additionally, it is the nighttime cortisol that is important to test in Cushing syndrome, as people with Cushing syndrome have high nighttime cortisol while normal individuals have low nighttime cortisol. In other words, they lose their diurnal rhythm of cortisol, with normal people having a high morning cortisol and low nighttime cortisol and people with Cushing’s syndrome having similar morning values and higher night time values. Night time cortisol is now usually assessed with late-night salivary cortisols (LNSC), but can be assessed by blood cortisol measurement at an emergency room or hospital.
Impact of Oral Estrogens and Birth Control Pills
Thirdly. patients taking oral estrogens or birth control pills will have a high morning cortisol, but it does not mean they have Cushing’s. That is because oral estrogen and birth control pills raise the cortisol-binding globulin (CBG) which leads to high total cortisol, as it is bound to the cortisol- binding globulin. Transdermal preparations of estrogen (gels and patches) do not affect CBG. However, the free cortisol which the cortisol receptors in the body sees, is normal. Many patients come to see me with a high morning cortisol due to being on birth control pills, and I need to explain to them that it does not mean they have Cushing’s syndrome.
Contact Dr. Friedman to Learn More About Cushing’s Syndrome
If you would like more information, please do not hesitate to make an appointment or visit Dr. Friedman’s website at goodhormonehealth.com.