Unusual Increased β-Globulins in an Elderly Patient

A 90-year-old man who had a history of transurethral prostate resection for benign prostatic hyperplasia was admitted for left hip pain. A hip radiography examination revealed a large osteolytic lesion in the left greater trochanter, and a bone scintigraphy evaluation showed increased activity in the same area. Because of the patient's history, metastasis from prostate carcinoma was suspected, and bone biopsies were performed the same week. Ten days later, the patient was hospitalized in the emergency department after a fall that fractured the femoral neck. At admission, plasma sodium, chloride, and potassium concentrations were all within their respective reference intervals. The plasma concentration of total protein was 5.0 g/dL (50 g/L) [reference interval, 6.0–8.0 g/dL (60–80 g/L)], and that of albumin was 1.5 g/dL (15 g/L) [reference interval, 3.0–4.5 g/dL (30–45 g/L)]. The albumin-corrected calcium concentration was 10.8 mg/dL (2.69 mmol/L) [reference interval, 9.0–10.6 mg/dL (2.25–2.65 mmol/L)]. Hematology tests showed mild normocytic (mean corpuscular volume, 95.1 fL; reference interval, 80–97 fL]), aregenerative [reticulocyte count, 54 × 103/μL (54 × 109/L); reference interval, 25–80 × 103/μL (25–80 × 109/L)] anemia, with a low hemoglobin concentration [9.9 g/dL (99 g/L); reference interval, 13.0–17.0 g/dL (130–170 g/L)] and leukopenia [2.5 × 103/μL (2.5 × 109/L); reference interval, 4.0–10.0 × 103/μL (4.0–10.0 × 109/L)]. The plasma creatinine value was 1.1 mg/dL (97 μmol/L) [reference interval, 0.71–1.20 mg/dL (62–106 μmol/L)], and the urea nitrogen concentration was 35.0 mg/dL (12.5 mmol/L) [reference interval, 7.8–19.6 mg/dL (2.8–7.0 mmol/L)]. The urine protein value was 540 mg/24 h (reference interval, 0–150 mg/24 h). Urine protein electrophoresis (UPEP)4 showed the presence of an unusual spike in the β region (Fig. 1A). We measured an increased urine concentration of free κ light chain …