A 60-year-old woman with a history of rheumatoid arthritis, smoking of 60 packs/year, chronic obstructive pulmonary disease, and treated hypertension underwent a screening colonoscopy and then felt poorly for a week. She saw her family physician, who referred her to the local hospital clinic, where they did the test listed in the table below. Laboratory results Test Results Reference Range Creatinine 3.7 mg/dL Women <1.2 mg/dL BUN 35 mg/dL 5-20 mg/dL Creatinine clearance 12.5 mL/min 75-115 mL/min C3 148 mg/dL 80-200 mg/dL C4 19 mg/dL 15-80 mg/dL Albumin 4.1 g/dL 3.5 – 5.0 g/dL Calcium 9 mg/dL 8-10 mg/dL Phosphorus 4.6 mg/dL 2.5 – 4.5 mg/dL Cryoglobulin screen negative Serum protein electrophoresis – polyclonal hypergammaglobulinemia with no monoclonal immunoglobulin spike identified. Urine protein electrophoresis – protein 15.9 mg/dL with normal immunofixation electrophoresis Urine sediment - no RBCs, 4 – 8 WBCs/hpf, granular and hyaline casts Her creatinine and BUN levels 2 weeks after the colonoscopy were 4.6 and 46 mg/dL, respectively; a baseline (from previous physician’s office testing) serum creatinine was 0.9 mg/dL. Laboratory results are show 1. What disease state is the most likely explanation for the patient’s laboratory results? 2. What is the significance of the polyclonal hypergammaglobulinemia with no monoclonal immunoglobulin spike identified on SPE? 3. Is the patient’s urine protein normal? 4. Describe the immunofixation electrophoresis method.