Unrecognized secondary causes of hypertension in patients with hypertensive urgency/emergency: prevalence and co-prevalence.

BACKGROUND

Hypertensive urgency/emergency occurs frequently, yet no prospective data on common secondary causes, including sleep apnea (SA), renal artery stenosis (RAS), and hyperaldosteronism, are available.

METHODS

Patients presenting to the emergency room for over 1 year with systolic blood pressure > or =180 mmHg and/or diastolic blood pressure > or =100 mmHg and typical symptoms were included. RAS was diagnosed by direct duplex/Doppler ultrasound of the renal artery, resistance index, and imaging. The aldosterone/renin ratio (ARR) was determined from morning blood samples taken with the patients supine after > or =2 h of rest. A positive ARR (>50) was followed by saline infusion to exclude primary hyperaldosteronism. SA was evaluated by nasal breathing flow screening; when positive [apnea/hypopnea index (AHI) >5/h], complete polysomnography was performed.

RESULTS

Of 161 patients (age, 66.0 +/- 13.1 years; BMI, 28.6 +/- 5.1 kg), 131 had previously identified hypertension (duration, 12.7 +/- 11.5 years; 1.9 +/- 1.5 antihypertensive medications). SA was found in 114 (70.8%) patients [18% mild (AHI: 5-15/h), 26.8% moderate (15.1-30/h), and 24.2% severe (>30/h)]. Aldosterone levels exceeded 160 pg/ml in 22 of 23 patients with hyperaldosteronism; 4 had primary and 12 had secondary hyperaldosteronism. Thirteen (8.1%) patients had RAS. Three secondary causes were found in 1 patient (0.6%), > or =2 in 25 (15.5%), and > or =1 in 124 patients (77.0%). Of 150 detected secondary causes, only 5 were recognized previously.

CONCLUSIONS

Secondary causes of hypertension are common and predominantly unrecognized in patients with hypertensive urgency/emergency. Co-prevalence of secondary causes occurs in about 15% and should be considered before therapeutic intervention.