A 55-year-old man comes to the physician complaining of joint pain. He has had 2 years of intermittent and mild arthralgias of his hands, wrists, and shoulders at night. He recently developed pain in his wrists and hand pain with flexion mainly at the second and third metacarpophalangeal joints. He has no morning stiffness or warmth or redness around his joints. There is no history of fever, weight loss, or subcutaneous nodules. His medical problems include type 2 diabetes mellitus diagnosed 5 years ago and hypertension and hyperlipidemia diagnosed 3 years ago. Mild liver function abnormalities were detected and attributed to possible fatty liver 2 years ago. His medications include metformin, lisinopril, and rosuvastatin.
The patient's vital signs are within normal limits. BMI is 34 kg/m². There is swelling of the metacarpophalangeal joints bilaterally. He has no synovial swelling or abnormalities of his proximal and distal interphalangeal joints. There are no abnormalities of the wrists, shoulders, or hips.
X-rays of the hands and wrists reveal narrowing of the third, fourth, and fifth metacarpophalangeal joints with hook-shaped osteophytes at the metacarpal heads. Erythrocyte sedimentation rate is 15 mm/hr.
Which of the following would most likely show the cause of this patient's current symptoms?

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11ec193a_9928_85ba_853d_559b0acfcdc6_MD0002_00 11ec193a_9928_85bb_853d_bbdc80bfa6e6_MD0002_00 This patient's diabetes mellitus, atypical degenerative joint disease, and history of liver function abnormalities suggest likely hemochromatosis. Differentiating idiopathic primary osteoarthritis from secondary forms of osteoarthritis can be difficult. Secondary causes of osteoarthritis include trauma, underlying inflammatory arthritis, infection, calcium pyrophosphate deposition disease, and metabolic disorders (eg, hemochromatosis). Primary osteoarthritis of the hands most commonly involves the proximal and distal interphalangeal joints and the first metacarpophalangeal (MCP) joint. This patient's narrowing of the third, fourth, and fifth MCP joints and the findings of hook-shaped osteophytes strongly suggest hemachromatosis as the cause of the arthritis. Secondary osteoarthritis occurs in 40-60% of patients with hemochromatosis and can present with arthralgias, hand involvement (eg, wrist), and shoulder pain (see table). Screening this patient for hemochromatosis initially with serum transferrin saturation is the next appropriate step, as high levels correlate with arthritis. (Choice A) Rosuvastatin may cause mild liver abnormalities and myalgias in the proximal muscles but typically does not cause hand arthritis, as seen in this patient. (Choice B) HLA-B27 is linked to spondyloarthropathies (eg, ankylosing spondylitis, reactive arthritis, psoriatic arthritis). However, this patient does not have other clinical features (eg, back pain, inflammatory eye disease, enthesitis, sausage digits) seen in many spondyloarthropathies. (Choice C) Although hemochromatosis can sometimes mimic rheumatoid arthritis (RA), this patient does not have other clinical features (eg, morning stiffness, subcutaneous nodules) of RA. In addition, the low sedimentation rate makes this less likely. (Choice E) Chronic tophaceous gout typically results in bone erosions with characteristic thin "overhanging" edges. Educational objective: Hemochromatosis is a metabolic disorder often associated with secondary osteoarthritis. Patients usually have pain in the hands (especially the second and third MCP joints), hips, knees, and shoulders. Typical radiographic findings include chondrocalcinosis and hook-like osteophytes on the metacarpal heads. Elevated serum transferrin saturation correlates with the presence of joint disease. __________ References: Arthropathy of genetic hemochromatosis: a major and distinctive manifestation of the disease. (http://www.ncbi.nlm.nih.gov/pubmed/11247337) Musculoskeletal disease burden of hereditary hemochromatosis. (http://www.ncbi.nlm.nih.gov/pubmed/20722017)

A 55-Year-Old Man Comes to the Physician Complaining of Joint