Medical Case Details:
You are called by the surgical intern to see a 68 year old man in the surgical ICU because of new onset azotemia. He has a history of smoking, hypertension, osteoarthritis, and peripheral vascular disease, and was admitted three days earlier for unstable angina. His pain was refractory to maximal medical therapy. So, he underwent cardiac cath and subsequently three vessel coronary bypass grafting 48 hours before your call from the intern. His postoperative course was complicated by a non-ST segment elevation myocardial infarction (NSTEMI) but was otherwise unremarkable until yesterday when his urine output began to diminish (total of 150 cc over 24 hours), and his serum creatinine was noted to be 3.5 mg/dl (previous creatinine was 1.2 on admission). The patient is intubated and can give no history. Medications include Furosemide, Lisinopril, intravenous Nitroglycerin, Ibuprofen, and perioperative Cefazolin.
PE reveals an intubated alert man in no acute distress. T 97.3, P 96, R 12, BP 110/66. SKIN - no rash or lesions noted, normal turgor. LN - none palpable. No jugular venous distension. HEENT - conjunctivae are benign, fundi reveal grade 2 arteriosclerotic hypertensive changes, oropharynx is intubated and poorly visualized. CHEST - clear on the ventilator, sternotomy incision looks normal, COR - RRR with distant heart sounds, no murmurs or rubs. ABD - soft non-tender, without organomegaly, no flank tenderness, bowel sounds are diminished. G/R - Foley catheter in place, rectal normal, heme negative. NEURO - nonfocal. EXT - saphenous vein harvest site benign, no edema.
LABS Na 133, K 4.5, Cl 100, HCO3 20, BUN 49, Cr 3.5, glu 132, Hb 13.6, Hct 40.2, WBC 8.6, plts 400K UA: clear/1.015/no protein, glucose or ketones/sediment reveals occasional hyaline casts, moderately pigmented granular casts, and many renal epithelial cells. There are a few RBC and rare WBC. EKG: NSR 90/nl axis and intervals, inverted T waves are noted in the anterior leads. CXR - normal heart size, no CHF or infiltrates noted.
Will you consider doing a renal biopsy in this case? If yes, why? If no, why?