31-year-old female, with a history of controlled SLE, presents to your office with a 2 week history of headache, weakness, dizziness, and nausea. She also reports a new rash on her legs that is non-pruritic. She denies any recent illnesses, sick contacts, vomiting, abdominal pain, cough, or shortness of breath. She has been taking hydroxychlorquine for her SLE and has had little complications from this disease.
BP-131/72, HR-116, RR-15, O2-100%, T-101.2 F
General – Mild distress
Neck – Supple, no LAD
Pulmonary – CTA without adventitial breath sounds
CV – Tachycardic without M/G/R
Abdomen – S/NT/ND
PV – 2+ throughout
Neurologic – 5/5 strength throughout, 2+ reflexes throughout
Psychiatric – A&Ox3
What is the most likely diagnosis?
What other laboratory tests can be helpful in making the diagnosis?