A 43-year-old woman presented to the emergency department with confusion and gingival bleeding. She did not have a prior medical history and did not use any medications.
A few days earlier, she complained of flu-like symptoms. Her husband had noticed that for the past 24 hours she was somewhat confused and before arriving at the emergency department she had one episode of generalized tonic-clonic seizure.
Her temperature was 37 °C, heart rate 123 bpm, blood pressure 126/76 mm/hg, respiratory rate 26 breaths per minute, and oxygen saturation 96 % while breathing room air. The patient was disoriented in time, place and person, but showed no focal neurological signs. There was coagulated blood in the nostrils and oral cavity, and petechiae on the lower extremities. Examination of heart, lungs and abdomen was normal and there was no blood on the rectal digital examination.
The initial laboratory results showed a WBC of 8300/mm3 (N 4-10 000) with a normal differential count, Haemoglobin 5.3 g/dL (N 12-14), MCV 90 fL (N 80-100), reticulocytes of 200 000/mm3, and a platelet count of 21,000/mm3 (N 150 -400 000 /mm3). There were normal coagulation tests (PT 11 sec (N 11-12.5), aPTT 29 sec (N 25-36), fibrinogen 150 mg/dL (N 130-330). Serum electrolytes and renal function were normal. Liver tests showed elevated LDH and bilirubin levels 3.2 mg/dL (N <1.2), mostly indirect/free, AST and ALT were normal. C-reactive protein: 6 mg/L (N < 5 mg/L)
A Covid test and Beta-HCG test were negative.
What is the most appropriate first step for this patient?