What Causes Low Platelet Count In Blood?

I am sending details of Suma Thomas ,Female, 31 mother of 2 baby younger one 8 months old suffering from low platelets count and she is working in Kuwait as nurse.

When she was suffering from Bleeding on the inside of the mouth, such as from the cheeks ,gums and red spot in the skin they consult the doctor (Kuwait ministry hospital Farvania )and checked the blood then it was found very low platelets count almost zero and immediately she had taken the below mentioned medicine
immunoglobuline 1gm/body wt

injection metheyil prednisolon 1 gm/ 3 days

tablet prednisolon 45 mg od

Then platelet count gradually goes to 150000 and they relieved from the hospital after one week she had the above mentioned problem and checked the platelet count it was 3000, again she undergoes the above mentioned treatment and platelet count rise to 124000 after two days ,today 22/8/11 it reduce to 60000 and they did the attached test and they couldn't diagnose the problem and they refereed to other hospital what shold we do...