Always my RN suggests two readings of BP each time I run into her clinic. She takes the average of the two and puts in my record. She takes the reading 15 minutes apart after considerable sitting.
I found out that the normal BP reading should be less than 120 ( above one) and less than 80 ( below one) not any one of them. Since it is 150 / 100 for you, you might want to recheck. Hope it helps you.