Hypertensive Patients referring to our center will undergo a systematic diagnostic workup aimed at finding the cause(s) of their high blood pressure. Information prospective and retrospectively obtained will be analyzed while guaranteeing anonymity.

The Investigators will retrospectively enroll consecutive patients attending the outpatient clinic of the Specialized Hypertension Center at the Department of Medicine of the University of Padua from January 1 st 2017 to January 31 st 2023. The data obtained from the review of clinical chart and findings from biochemical and radiological examinations will be recorded in a secured database and will be analyzed in an anonymized and aggregated form.

Per Investigators' practice, during the first visit, patients attending our Referral Center undergo a complete clinical evaluation entailing extensive medical history and supine and standing office blood pressure measurement, ECG and are offered a screening for secondary hypertension. To this end, patients are usually switched to treatment with a long-acting calcium-channel blocker, mostly verapamil slow-release and/or doxazosin, for at least 6 weeks beforebiochemical testing.

From 2020, based on the results of the "Effects of Mineralocorticoid and AT1 Receptor Antagonism on the Aldosterone-Renin Ratio in Primary Aldosteronism" (EMIRA), 13 those with difficult-to-control hypertension and/or hypokalemia also received a mineralocorticoid receptor antagonist (MRA). As per institutional rules, at the Investigators' University Hospital all the patients are requested to sign a written consent for the processing of their data in an anonymized way for educational and research purpose. All the patients will receive exhaustive information about the need of screening for secondary hypertension, which entailed good clinical practice.

Biochemical data that will be recorded include serum Na + , K + , and ionized Ca 2+ levels, plasma active renin concentration (DRC), aldosterone concentration (PAC), used to compute the aldosterone-renin ratio (ARR), 24h urine Na + , K + , and Ca 2+ excretion, metanephrine and normetanephrine excretion in acidified urines, serum parathyroid hormone, thyroid-stimulating hormone, and free triiodothyronine and free thyroxine. The Investigators will also record data from renal Doppler ultrasonography, sleep questionnaires for sleep apnoea, sleep fragmentation, and daytime sleepiness, when performed. In patients who underwent second level imaging tests, e.g. abdomen MRI, CT or angio-CT and subtyping by adrenal vein sampling (AVS) or full poly-somnography, data from these additional tests will be registered.

Inclusion Criteria:

• age ≥18 and >/= 85 years

Exclusion Criteria:

• absence of a complete diagnostic work-up due to poor overall clinical conditions or lack of a clear benefit from it
• unwillingness or failure to complete the full diagnostic work-up and/or to attend the outpatient clinic follow-up visits after the first evaluation

Hypertensive patients refering to our center