Q: My daughter has been having very bad headaches for the last couple of weeks. We went to the doctor and blood work was done. The doctor said that her platelet level was 112 and four days later when blood work was done again, it was 92. What could be the cause for this? She is 19 and not pregnant, she has not been sick other than the bad headaches and has vomited during one headache. She does not do drugs and drinks rarely. Could this be an infection?

A:Platelets are a type of blood cells responsible for clotting of blood. Their normal number in blood is 150,000-400,000 per microlitre (mcl) of blood. A decrease in their number is called thrombocytopaenia. This may be caused by decreased production in the bone marrow or increased peripheral destruction. The usual cause is an immune-mediated destruction secondary to an infection or drug or some primary disease called idiopathic thrombocytopaenic purpura (ITP). Distinguishing ITP from other conditions is usually done clinically, paying careful attention to the onset of symptoms, family history, medication use, and recent illnesses. When thrombocytopaenia is severe (i.e. platelet count less than 20-30,000/mcl, a trial of immunosuppression is generally administered (prednisone or IV IgG). A rapid response (within a week) to these therapies helps confirm the diagnosis as ITP. Failure to respond should lead to further investigation of alternate causes.