Gout And Crystal Arthritis
Introduction
Gout is an inflammatory joint disease where uric acid crystals get depositied into the joint fluid and around the joint capsule.
Gout is actually only one of the manifestations of a faulty uric acid metabolism. Kidney stones are another manifestation. Apart from uric acid crystal disease there are other crystal-induced diseases such as pseudogout, which is produced by precipitation of another crystalized salt, calcium pyrophosphate dihydrate (CPPD). The other name for pseudogout therefore is CPPD crystal deposit disease.
Gout
Introduction:
Not everybody can handle uric acid in their system as well as the person next door. Uric acid is one of the breakdown products of meat. We are all born with slightly different enzyme patterns. However, the person that cannot break down purines as well will end up with too much uric acid in the system until it reaches a critical point of solubility where it preciptates as uric acid crystals.
When uric acid levels exceed 7.0 mg/dL (or 0.41 mmol/L) in plasma, a critical point is reached where monosodium urate crystals, which under the microscope look like micro-needles, will be spontaneously deposited in tissue with a lack of blood supply such as tendons, joints, ligaments or cooler tissues such as ear lobes. This point can also be reached in patients who have leukemia, lymphomas, hemolytic anemias or other cancers where purines are overproduced because of rapid cell division. Some children are born with an enzyme defect, which leads to uric acid kidney stones, severe gout and kidney damage at a young age. Most cases of gout though are in adults and are often associated with an overindulgence of meals containing large helpings of meat in combination with consumption of alcohol. This might be part of the explanation why males are much more commonly affected by gout then females (ratio of 20:1).
Pseudogout
(calcium pyrophosphate dihydrate crystal deposit disease or CPPD crystal disease)
Introduction
The clinical course is very similar to gout, except that the symptoms are not as acute as with gout. It appears that CPPD crystals are a byproduct of degenerative or metabolic tissue changes.
This explains why pseudogout is often associated with other rheumatological diseases such as calcific rotator cuff tendinitis, calcific bursitis, degenerative arthritis and gout. There are also associations with metabolic diseases such as hypothyroidism, hemochromatosis, hyperparathyroidism and amyloidosis (Ref. 2). CCPD crystal disease is a disease of persons older than 60 years of age.
Signs and symptoms:
Pseudogout presents as an acute attack similar to gout, affecting mainly the knee, wrist or shoulder. The diagnosis is often more difficult than that of gout as the CPPD crystals are not as concentrated in the synovial fluid. However, with centrifugation and a lab that specializes in its detection the diagnosis is now easier to make.
Treatment of pseudogout:
The acute joint pain responds very well to colchicine therapy. Antiinflammatories such as NSAIDs or Cox-2 inhibitors will help very well for arthritis of joints and for calcific tendinitis or bursitis cases affected by pseudogout. Maintenance therapy on low dose colchicine can be used longterm, but must be balanced by the physician and patient against the toxic side-effects on the bone marrow and kidneys. Occasionally there is a patient where all therapies fail and severe joint destruction results.
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