A 75-year-old male who was recently diagnosed with multiple myeloma presented to the urgent care clinic with worsening swelling of legs, scrotum, and penis. Because of external pressure of the urethra (from the swelling), the patient experienced difficulty voiding urine. Radiology imaging showed multiple lytic lesions in the skull, ribs, and iliac bone. The patient had been treated with standard chemotherapy (cyclophosamide, bortezomib, and dexamethasone). The patient denied having local pain, fever, shortness of breath, headache, or diarrhea. He had a history of colorectal cancer and received chemotherapy, but had no evidence of colorectal cancer. Renal ultrasound and Doppler of the lower extremity was unremarkable for deep venous thrombosis.
The patient's renal profile was suggestive of acute kidney injury (see chemistry and hematology results in Table 1). Magnesium, ammonia, potassium, carbon dioxide, chloride, calcium, bilirubin, alkaline phosphatase, aspartate transferase, alanine transferase, and anion gap were all within normal range.
The possible causes for acute kidney injury include myeloma or hypoperfusion of kidney as a result of …