With RA, small joints are mostly affected in an inflammatory, destructive manner. This is not observed in IH. Rheumatoid factor, cyclic citrullinated peptide antibodies and antinuclear antibodies are usually negative in IH. Palindromic rheumatism. Like IH, palindromic rheumatism (PR) is also characterised by relapsing, short-episodes of sudden onset arthritis with no recognisable trigger. However, unlike PR, IH affects the knee almost exclusively and there is a predictable periodic, regularity of attacks, with laboratory tests during attacks being generally unremarkable. PR is also more likely to be associated with development of rheumatoid arthritis. Familial Mediterranean Fever. For some patients with FMF, episodes of knee or joint inflammation may be the only presenting symptom during an acute inflammatory episode. The MEFV gene mutations associated with FMF have been implicated in the pathogenesis of both palindromic rheumatism and IH. Other conditions for consideration (or exclusion) are other periodic arthropathies, crystal arthopathy, prepatellar bursitis (housemaids knee), pigmented villonodular synovitis, trauma and infectious causes. Treatment
No treatment has been found to be routinely effective. NSAIDs and COX-2 inhibitors are not generally helpful other than for general pain relief. They do not seem to help reduce effusions or prevent their occurrence. Low-dose colchicine (and some other ‘anti-rheumatic’ therapies e.g. hydroxychloroquine) have been used with some success. (Use of methotrexate and intramuscular gold have not been reported in the literature).
Mutations in the ASS gene reduce the activity of the enzyme, which disrupts the urea cycle and prevents the body from processing nitrogen effectively. Excess nitrogen, in the form of ammonia, and other byproducts of the urea cycle, accumulate in the bloodstream, leading to the characteristic features of type I citrullinemia. Type II
The symptoms of type II citrullinemia (Online Mendelian Inheritance in Man (OMIM): 605814 and Online Mendelian Inheritance in Man (OMIM): 603471) usually appear during adulthood and mainly affect the central nervous system. Characteristic features include confusion, abnormal behaviors (such as aggression, irritability, and hyperactivity), seizures, and coma. Specific investigation like decrease citrulline level , increase ammonium ion . These symptoms can be life-threatening, and are known to be triggered by certain medications, infections, and alcohol intake in people with this type.Type II citrullinemia may also develop in people who had a liver disorder called neonatal cholestasis during infancy. This condition blocks the flow of bile and prevents the body from processing certain nutrients properly. In many cases, the  symptoms resolve within a year. Years or even decades later, however, some of these people develop the characteristic features of adult type II citrullinemia.Type II citrullinemia is primarily found in the Japanese population, where it occurs in an estimated one in 100,000 to 230,000 individuals. Type II has also been reported in people from East Asian and Middle Eastern populations. Mutations in the SLC25A13 gene are responsible for type II citrullinemia.