Testing Testing usually includes CT or MRI Tests for suspected infections (eg, complete blood count [CBC], blood cultures, chest x-ray, urinalysis) Evaluation for hypoxia (pulse oximetry or arterial blood gases) Measurement of electrolytes, blood urea nitrogen (BUN), creatinine, plasma glucose, and blood levels of any medications suspected to be having toxic effects A urine drug screen If the diagnosis is unclear, further testing may include liver function tests; measurement of serum calcium and albumin, thyroid-stimulating hormone (TSH), vitamin B12, erythrocyte sedimentation rate (ESR) and / or C-reactive protein (CRP), and antinuclear antibody (ANA); and a test for syphilis (eg, rapid plasma reagin [RPR] or Venereal Disease Research Laboratory [VDRL] test).