GOUT IN THE HAND
Gout is classified as a crystalline arthropathy, which means that the problem is a deposition of crystals. In this case, the culprit is sodium urate crystals. The crystals are deposited in the joint lining and joint fluid secondary to raised uric acid levels (hyperuricaemia) in the blood. There are many causes for raised uric acid levels: The normal process of breaking down blood cells is a cascade of multiple enzymes and a deficiency in any of these enzymes can precipitate the increase of some of these products. In gout, there is an increase of uric acid that cannot be reduced to a chemical structure that can be excreted by the urine.
This disease usually affects middle-aged men (40-60 years). The common presentation is a painful big toe (called a podagra) causing significant pain that can bring life to a standstill, literally. The disease can also affect the hand and the presentation is usually a painful red and swollen joint. The onset is sudden and usually very intense. Most gout sufferers have multiple flare ups. In acute disease, the joints become swollen with masses called “tophi”. Surgical excision of these masses reveals a toothpaste-like white material.
The diagnosis is usually made by a combination of the clinical picture and the demonstration of raised uric acid levels in the blood. Joints can be aspirated and the crystals can be seen under polarised microscopes where they exhibit a negative birefringence.
The management of gout is usually with anti-inflammatories. Colchicine is a common drug that is used to suppress the inflammation acutely. Furthermore, it is more important to prevent the raised uric acid levels by diet control, lifestyle modification and certain drugs (Probenecid or Zyloprim).
One of the differential diagnoses of a painful wrist in middle aged men, is Pseudogout.
Pseudogout presents very similarly to gout, with swelling and redness of especially the wrist. The key difference is that the uric acid level (which is raised in gout) is normal. In pseudogout, the precipitating culprit is calcium-pyrophosphate. This precipitates as crystals (rod shaped birefringent) in the cartilage of the wrist, especially on the ulnar sided TFCC (triangular fibro cartilage complex).
The diagnosis is often made by arthroscopical biopsies when infection is suspected. Treatment is conservative with anti-inflammatories and rest.