Sumaiya,
Welcome to thalassemia patients and friends. It is best to keep the hemoglobin between 9 and 10. At each transfusion the patient should be given between 14-16cc/kg(body weight) of blood.
Could you also provide us with the age of the patient and the ferritin level? Maintaining a healthy hemoglobin, eating balanced nutritious meals, exercising and ensuring that a healthy snack is provided between meals is helpful in reaching a healthy weight. Weight gain is desirable if the individual is underweight.
Best wishes and once again welcome to the site!
Sharmin