Elevated D-dimer is associated with rheumatoid because rheumatoid arthritis is known to cause elevated D-dimer, but the latter is not a marker for diagnosing rheumatoid arthritis. Elevated D-dimer is often indicative of thrombosis and hypercoagulability of the blood, as it is a degradation product of fibrin. Therefore, in addition to rheumatoid diseases, thrombolytic therapy, kidney disease, cerebral infarction, tumors, and tissue necrosis can cause elevated D-dimer. There are many rheumatic and rheumatoid diseases, and rheumatoid generally refers to rheumatoid arthritis. The patient’s serum RF (rheumatoid factor) is positive, and the blood sedimentation rate (ESR) may be elevated, and the diagnosis needs to be combined with joint involvement, morning stiffness, and duration of symptoms, as well as other laboratory findings, etc. Elevated levels of D-dimer can be used as an adjunctive indicator of the active stage of rheumatoid arthritis.