Mercury and other heavy metals may trigger an autoimmune reaction. Mercury is taken up by the cells of articular tissues.
The differential diagnosis is mercury poisoning in a person with pre-existing autoimmune disease.
Clinical features:
(1) The patient has a polyarthritis, often resembling rheumatoid arthritis, often with myositis.
(2) Other signs of mercury poisoning (renal disease, neuropathy, cognitive impairment, hypertension) may be dismissed in the elderly as signs of aging.
Laboratory findings:
(1) elevated mercury
Suggestive features:
(1) atypical course for an autoimmune disease
(2) poor response to appropriate therapy
(3) occurrence in a child or young adult
(4) improvement after treatment of the mercury poisoning
(5) acute onset
Findings suggestive of concurrent diseases:
(1) presence of autoimmune disease prior to mercury exposure
Reasons for a delay in diagnosis:
(1) absence of a known exposure to mercury
(2) not considering the diagnosis
(3) other symptoms of mercury poisoning minor, discounted or not observed
