High prevalence of secondary hypertension and insulin resistance in patients with refractory hypertension.

OBJECTIVE

To determine causes of treatment resistance in patients with refractory hypertension, and to estimate the prevalence of true resistant hypertension.

METHODS

We studied 50 consecutive patients referred with refractory hypertension after exclusion of hypokalemia and stenosis of the renal artery. Ambulatory blood pressure monitoring was performed in all patients to detect white-coat effect. The patients were hospitalized, antihypertensive drugs were withdrawn and a screening for secondary hypertension was performed. In addition, these patients, and a control group of essential hypertensives controlled with three antihypertensive drugs, underwent a OGTT with 75 g of glucose.

RESULTS

Primary normokalemic hyperaldosteronism was diagnosed in seven patients. Two patients had a pheochromocytoma and six had white-coat effect. The 35 remaining patients with true resistant hypertension shown significant differences in serum insulin and HOMA IR when compared with the control group.

CONCLUSIONS

These findings show that among normokalemic treatment-resistant hypertension, the presence of hyperaldosteronism and pheochromocytoma is quite high. Moreover, treatment resistance in hypertensive patients appears to be associated with insulin resistance.