Blood pressure at high altitude

Dear Ask The Doctor: I am a 56 y/o M. with a hx of hypertension. At home in the desert, the hypertension is controlled with a dose of 20mg lisinopril daily. When I travel to an alpine area above 5000ft the medication no longer works. My blood pressure soars. Why is that?

Dear Doug: The effects of altitude on blood pressure are variable. There is usually initial hypertension, followed by gradual normalization. After years of residence at high altitude blood pressure may actually be lower than that observed among residents at sea level. If you have hypertension at low altitude, your blood pressure may tend to be higher for the first two weeks at altitude, sometimes longer. If your blood pressure becomes too high, your medications may need to be increased, and then decreased when you return to low altitude. Most visitors travelling to high altitude have a slight increase in blood pressure (and heart rate) that is of no concern, while some have a slight decrease and a few individuals have an abnormally high blood pressure response. This is due mostly to elevated stress hormones (adrenaline and noradrenaline) in the blood due to the stress of low blood oxygen at higher altitudes. Patients with diagnosed hypertension more often have an even higher blood pressure response at altitude, and occasionally, the blood pressure may become dangerously high. Mild to moderate hypertension (high blood pressure) is usually asymptomatic. Severe hypertension may cause headache, visual disturbances, nausea, vomiting and confusion. If you develop any of the above symptoms at high altitude, I would recommend seeking urgent medical advice