what causes low blood platelets? my friend is a male 70 years old. he says he is being treated for a deep lung infection. he said the antibiotics did not cure the problem. he said he had to go in a couple times a week for treatments. he said it would take about 6 weeks. i am not a doctor, but i have never heard of this type of treatment for a lung infection. he said last night he started feeling sick and went in to the hospital this morning for a blood transfusion because his blood platelets were low. he has lost 40 to 50 pounds in last 3 months. all of his friends suspect cancer, but he says its only an infection. ???