Volunteers are selected based upon the results of the screening procedures and lab tests, among the leading causes of rejection are lab results that show abnormalities in the blood or urine. Besides testing your blood for HIV and hepatitis, most clinics check if your blood has enough red cells (cells created by iron) and haemoglobin (the protein in red cells that contains iron) , and a normal number of white cells (cells that protect against infection and illness). If your blood is low in either red cells or haemoglobin, then this means you have an iron deficiency, and you might be anaemic.
This is usually resulting from a loss of blood. Naturally, many women become anaemic during their period. You can build up your iron stores by taking iron supplements whenever necessary, or by eating a lot of iron-rich foods. If your blood is low in white cells, then your immune system is weak, and you have a greater risk of contracting infections such as cold and flu. Also, exposure to viruses and bacteria may lead to an increase in your number of white cells which is necessary to fight an infection. Therefore, if too many white cells are present in your blood, this may indicate you already have an infection.
You can limit exposure to germs by washing your hands regularly, and you can keep up your resistance by getting adequate rest and by avoiding too much strenuous exercise. If you do get sick, drink plenty of water to flush out your system, which can help speed your recovery. Urine samples are routinely tested for drugs of abuse, alcohol, and common medications. They may also be tested for the presence of blood, sugar, and protein, any of which may be considered an indication of possible infection or disease. To improve the chances of all the test results being normal, you will want to eat a healthy balanced diet, avoid excessive drinking, and avoid using drugs or medications if at all possible.