RESPONSE TO THE COLD PRESSOR TEST IN NORMOTENSIVE AND HYPERTENSIVE PATIENTS

The response to the cold pressor test (CPT) was studied in 49 normotensive (NT) and 73 patients with essential sustained hypertension (HT). Patients were classified as responders when they increased their systolic pressure (SBP) by at least 16 mm Hg or their diastolic blood pressure (DBP) by at least 12 mm Hg. Forty-seven out of seventy-three (64%) increased their mean blood pressure (MBP) by 18.6 +/- 1.4 mm Hg (mean +/- SEM) in response to CPT. In NT subjects 23 out of 49 (47%) were responders (MBP = 16.3 +/- 1.3 mm Hg). In NT, but not in HT, patients, a negative relationship was observed between MBP changes during CPT and age (P < .001) or basal DBP (P < .01). There was no relationship between blood pressure response and the presence of a family history of hypertension. A positive correlation was found in HT patients between basal levels of active renin (AR) in the upright position and MBP changes during CPT (P < .001). Mean plasma AR was 24.2 +/- 3.5 pg/mL in nonresponders v 37.5 +/- 2.9 pg/mL in responders (P < .001). In HT, but not in NT, patients, blood pressure changes were associated with a simultaneous increase in HR (P < .01 between DELTA-MBP and DELTA-HR). These results suggest that blood pressure elevation during CPT is a very common reaction in young normotensive subjects especially in those that have the lowest mean blood pressure. Therefore it is unlikely that CPT may be used as a predictor test of future hypertension in this population. Additionally, in hypertensive patients the blood pressure elevation during CPT reflects an age-independent sympathetic overactivity.