question: my bp is very erratic; in the morning usually about 131/72 - but now in the evening is is 140/72.  The lower number hardly ever goes above 80.  I am female, age 69, 5'4 and weight 148.  I am very healthy. Is that prehypertension?  Do I need to take lisinopril?  When I take 1/2 of my husband's lisinopril, my bp goes way down for about a day and a half.  I take no medicine whatsoever.  Thank you