 [ Symptoms ] i have a sinus infection and on antibodics but i have this constant dry cough what can i do about the coughing [ Disease ] this was an estimation of course since the amount a blood that an adult human can be variable blood counts like a hemoglobin or hematocrit can determine to some degree the level of anemia by giving blood one unit at a time and watching the response to those tests a medical provider can estimate blood loss based on how much blood it takes to return those number to normal again just like adding oil to a car and checking the dipstick