Miscellaneous metabolic diseases.

Musculoskeletal manifestations are commonly observed in metabolic disorders. Here we review the recent literature on several metabolic arthropathies. Hemochromatosis should be suspected in patients with the sign of the "iron salute". Screening for this disorder by routine measurement of transferrin saturation appears to be a cost-effective procedure in white men aged 30 years or older. In dialysis arthropathy, radiologic lesions of the hand joints increased in size and frequency with the duration of dialysis. However, destructive arthropathy of the fingers is not necessarily related to amyloid deposition. In patients with dialysis-related beta 2-microglobulin amyloid deposition, renal transplantation improved clinical rheumatologic manifestations but did not prevent progression of destructive arthropathies nor dissolution of amyloid deposits. In ochronotic arthropathy, spinal changes may resemble those seen in ankylosing spondylitis and can lead to cord compression. The presence of brownish-blackish rods in the synovial fluid is an unusual but useful diagnostic tool. Metabolic factors are likely to play a role in the pathogenesis of diffuse idiopathic skeletal hyperostosis, and recent studies have demonstrated elevated insulin and growth hormone but normal insulin-like growth factor-1 levels in these patients. Other metabolites that may play a role in this condition include retinoids and bone morphogenetic protein-2.