Intra-tubular amyloidosis

A 52-year-old man with a past medical history of asthma, well-controlled diabetes and hypertension was referred to our hospital for acute renal failure. The patient reported a 2-month history of fatigue and arthralgia involving his shoulders, elbows, wrists, metacarpophalangeal joints as well as his knees and ankles. Six weeks before admission, he started naproxen 400 mg twice daily without improvement. Subsequently he was evaluated by a local rheumatologist who suspected rheumatoid arthritis and started him on prednisone 30 mg daily. A month later, his laboratories revealed an elevated serum creatinine (12.3 mg/dl, 1087 mu mol/ l) and potassium (7.9mEq/l). His serum creatinine was 1.8 mg/dl (159.1 mu mol/l) 6 weeks earlier and 1.3mg/dl 7 years earlier (Figure 1). The hyperkalemia was treated with intravenous insulin and dextrose, and he was admitted to our hospital for further management. He denied fever, chills, weight loss, shortness of breath, lower extremity edema, and did not have any uremic symptoms (no nausea, vomiting, hiccups, or itching). He had normal urine output and no dysuria or hematuria. He had hypertension that was diagnosed 13 years earlier and based on records it was well controlled (< 135/85) on enalapril 10 mg daily. His diabetes was diagnosed 4 months earlier and treated with rosiglitazone 4 mg once daily. He had not been evaluated for retinopathy. He had no prior urine analysis to assess the presence of albuminuria. His other medications included fluticasone aerosol, albuterol/ipratropium puffs, acetaminophen two tablets at bedtime, and prednisone 30 mg daily. On physical exam his initial blood pressure was 162/70 with a heart rate of 102/min, regular. Orthostatic blood pressure was not checked. He was afebrile. His mucous membranes were moist. His cardiac exam was normal with no pericardial rub and jugular veins were flat. His lungs were clear and abdomen soft with no organomegaly. The skin was normal. His joint exam revealed synovitis in his elbows, wrists, metacarpophalangeal joints, knees, and ankles bilaterally. He had stiffness and decreased range of motion in his elbows, wrists, and ankles. His admission laboratories are shown in Table 1A and 1B.