A 38 year old woman presents to the ER with 1 week of fevers and malaise. Serum creatinine 1 year ago was 54 micromol/L. 2 days ago when measured in a walk in clinic it was 97 micromol/L. In the ER, her blood pressure is 160/104 mm Hg and serum creatinine is 173 micromol/L. Urinalysis reveals 3+ protein and 3 + blood. Her microscopy shows red blood cells and red blood cell casts.
What would be in your differential diagnosis? What tests would you order at this point?