My haematocrit level is low - 24% - and i have nausea, headaches and fatigue. i am 46yrs, female. should i be concerned?

Yes, worry, but...: Lab results usually are numbers, and numbers are just numbers, with little meaning unless a doctor takes in the whole picture of what's going on with the patient. Getting all the details around a set of numbers is helpful in making interpretations. One's primary care doctor can evaluate, but with a very low blood count coming with symptoms of anemia, one may need to be evaluated in the hospital.