A 9-year old girl presented with new onset type-1 diabetes, diabetic ketoacidosis, cerebral edema, multifocal vasogenic brain lesions and lower limbs peripheral paresis. In addition, this child developed polydipsia and polyuria one week before admission to the hospital.

Laboratory tests disclosed an initial blood-glucose level of 1136 mg/dl and acidosis (pH 7.1; BE-25.9).

What other diagnostic tests should be recommended for this patient?