Gout or Pseudogout? 

Gout and “pseudogout” — known formally as calcium pyrophosphate dihydrate crystal deposition disease (CPPD) — have such similar symptoms that it usually takes a microscope to know for sure what you’ve got. 
Each of these painful forms of arthritis is caused by a different type of crystal in the joints, and remedies differ. 
“The big difference is that gout is a treatable disease. If it can be diagnosed and treated properly, gout can go away completely,” says rheumtologist Alan Baer, MD, professor of medicine and director of the rheumatology clinic at Johns Hopkins Medicine. 

Symptoms 
Gout: Abrupt onset of a red, hot, swollen, painful joint, most often in big toe, but less frequently in the foot, ankle, knee, wrist, elbow or finger; usually confined to just one joint in early disease. 
CPPD: Abrupt onset of a red, hot, swollen, painful joint, most often knee, wrist or ankle; sometimes in spinal ligaments, causing neck pain; may affect one or more joints. 

Causes 
Gout: High uric acid levels cause monosodium urate crystals to form in and around the joint, resulting in inflammation and joint damage. 
CPPD: CPPD crystals build up in cartilage, triggering inflammation and pain. Age and genes are risk factors. Other conditions may play a role. 

Diagnosis 
Gout: Medical history, physical exam, blood tests, joint fluid aspiration and analysis, X-ray, ultrasound, CT scan. 
CPPD: Same, except CT scan is not done. 

Treatment 
Gout: For acute attack/flare: NSAIDs, corticosteroids, colchicine. For disease management: Dietary changes and uric-acid lowering drugs to prevent attacks. 
CPPD: For acute attack/flare: NSAIDs, corticosteroids, colchicine.