My doctor has suggested taking hydrochlorothiazide for blood pressure. It's a diuretic. With the new guidelines for what constitutes high blood pressure my latest reading of 140/90 is considered high. Past readings have been around 135/85. My concern is that taking a diuretic will result in my blood being thicker and my hematocrit, which usually tests at the top of the normal range, will become an issue. Admittedly, I really don't understand how this med works. Do I have anything to be concerned about?