This is a non-interventional study to assess the prevalence of endogenous hypercortisolism (eHC) in patients with resistant hypertension (rHTN) and will enroll approximately 1000 patients at approximately 45 sites in the United States (US).

Each patient will have an initial visit for screening. After eligibility is confirmed, a limited exam will be performed and demographic and medical history will be collected. Non-fasting labs and a urine collection will also be done. A second visit will be a fasting blood draw at 8 AM after taking 1 mg of dexamethasone the night before at 11 PM. Cortisol level and study labs will also be collected.

After the lab results are obtained, a third visit will be scheduled only for patients with eHC and will include a non-fasting blood draw at 8 AM and scheduling of a non-contrast CT scan.

This is a non-interventional study enrolling approximately 1000 patients at approximately 45 sites in the (US) and will assess the prevalence of eHC in patients with rHTN.

For the purpose of this study, eHC is defined by post-dexamethasone suppression test (DST) cortisol > 1.8 μg/dL with serum dexamethasone levels ≥ 140 μg/dL in a population meeting the inclusion and exclusion criteria for this study.

rHTN is defined by the American Heart Association as 1) systolic blood pressure (SBP) above target (≥ 130 mmHg for purposes of this study) despite concurrent use of 3 or more antihypertensive medications from different classes including a diuretic at their maximally tolerated doses or 2) at target or above target SBP requiring concurrent use of 4 or more antihypertensive medications from different classes.

Each patient will have an initial visit for screening. After written informed consent and eligibility is confirmed including a urine pregnancy test (if applicable), blood pressure, weight, height and waist circumference will be checked, and medical history will be obtained. Non-fasting labs such as plasma renin activity, aldosterone, N-terminal-pro brain natriuretic peptide, complete blood count, high sensitivity C-reactive protein, hemoglobin A1c, and comprehensive metabolic panel will be collected. A urine test will also be performed for albumin to creatinine ratio.

A second visit will be at 8 AM (± 1 hour) the morning after taking 1 mg of dexamethasone at 11 PM the night before. The blood draw must be in the fasted state and will include cortisol level, lipid panel, adrenocorticotropic hormone (ACTH), and fasting glucose. Dexamethasone level will be checked automatically for any cortisol >1.8 μg/dL (eHC).

After the DST results are obtained, a third visit will be scheduled only for patients with eHC and will include a non-fasting 8 AM blood draw for ACTH and cortisol and scheduling of a non- contrast adrenal CT scan.

Inclusion Criteria:

• Each patient must meet all of the following criteria to be enrolled in the study:
• Signed and dated Institutional Review Board (IRB)-approved informed consent form (ICF) prior to any study-specific screening procedures.
• Male/female patients must be 18 years or older at the time of signing the informed consent.
• Meet either of the following criteria:
• Has rHTN, defined by the American Heart Association as BP above target (systolic ≥ 130 mmHg for purposes of this study) despite concurrent use of 3 or more antihypertensive medications from different classes at their maximally tolerated doses, and 1 of these agents is a diuretic.
• Or, has rHTN, defined by the American Heart Association as SBP at target or above target requiring concurrent use of 4 or more antihypertensive medications of different classes.

Exclusion Criteria:

• Patients who meet any of the following criteria will not be permitted entry to the study:

• White coat hypertension, ie, elevated BP in the office only, as determined by the Investigator.

• Non-adherence to BP medications, as determined by the Investigator.

• Systemic glucocorticoid medications exposure (excluding inhalers or topical) within 3 months of screening. For temporary exposures to oral glucocorticoids the Medical Monitor may be consulted to determine eligibility.

• Has an historical estimated glomerular filtration rate (eGFR) < 30.

• Has severe untreated sleep apnea as determined by the Investigator.

• Has excessive alcohol consumption (eg, > 14 units/week for male, > 7 units/week for female) as determined by the Investigator.

• Has severe acute psychiatric, medical, or surgical illness, as determined by the Investigator.

• Is a woman who is pregnant or lactating. For women of childbearing potential, a urine pregnancy test must be negative before doing the DST. A woman of childbearing potential includes women < 50 years old, women whose surgical sterilization was performed < 6 months ago, and women who have had a menstrual period in the last 12 months.

• Is a woman who is on oral contraceptive pills (OCPs). Women on OCPs may be screened but must be willing and able to stop OCPs for at least 6 weeks prior to screening assessments. OCPs can be resumed immediately after the blood draw for the DST.

• Has history of congenital adrenal hyperplasia.

• Has had the diagnosis of Cushing syndrome and/or has used or plans to use any of the following treatments for Cushing syndrome:

  • Mifepristone, metyrapone, osilodrostat, ketoconazole, fluconazole, aminoglutethimide, etomidate, octreotide, lanreotide, pasireotide, longacting octreotide or pasireotide.

• Is unable to take dexamethasone due to a history of hypersensitivity or severe reaction to dexamethasone.

• Is a staff member working directly on the study or is a family member of someone working directly on the study, including any of the Sponsor's employees, the Investigator or the site staff.

Office-based care and university clinics in the United States.

Upon study completion, results will be presented at relevant scientific congresses and published in a peer-reviewed journal.