Inflammation. Reiter's syndrome is sometimes termed reactive arthritis. In susceptible individuals (often with marker called hla b27 in their blood), there is joint inflammation, as well as inflammation of the urethra and conjunctivitis. The reaction may be to a prior infection elsewhere in the body. Reiter's should be evaluated and treated by an ophthalmologist and rheumatologist.
Autoimmune condition. Reiter's syndrome or reactive arthritis is an autoimmune response to a triggering infection somewhere else in the body, often the gastrointestinal tract or the urinary tract. The symptoms are inflammation of a large joint or joints or the spine plus sometimes the eye, the skin, or the cervix, penis, or urethra. The cause is not always found but most cases respond to treatment.