What is pseudogout? My twin brother was just diagnosed with this, so I'm wondering if I'm next. What should I watch out for?

Pseudogout means false gout. Like gout, pseudogout is a form of rheumatoid arthritis. It has a similar clinical presentation as gout (red, swollen, painful joints), but the underlying causes are different.

In the case of gout, the body produces too much uric acid (a condition called hyperuricemia). Hyperuricemia causes urate crystals to form and get dumped in the bloodstream. The crystals of monosodium urate (MSU) or uric acid are then deposited on the articular cartilage of joints, tendons and nearby tissues.

People with gout experience painful attacks of arthritis when these crystal deposits build up forming pockets of crystals or nodules called tophi (singular form: tophus). The body sets up an inflammatory response to these crystals. The big toe is affected most often, but other joints can become swollen and painful.

Like gout, pseudogout causes sudden, severe pain in a joint, triggered by crystals in the joint lining. But the type of crystals involved are different between these two conditions. Pseudogout occurs when calcium pyrophosphate dihydrate (CPPD) crystals are deposited in the connective tissues. Gout tends to primarily affect the big toe. Pseudogout usually affects the large joints such as the hips and knees.