This page on gout and pseudo gout was last reviewed or updated on 29 August 2010.
Pseudo gout and gout are not the same, but at first glance may seem so. Gout is characterised by deposits of monosodium urate crystals (MSU). Pseudo gout is caused by crystals made from calcium pyrophosphate dihydrate. Hence it's sometimes called CPPD disease, or to spell it out just once, calcium pyrophosphate dihydrate deposition disease. Pseudo gout may also be called chondrocalcinosis, but only in med-tech literature.
Pseudo gout misspellings: sudo gout, psudo gout, psuedo gout.
Pseudo gout symptoms are also inflamed and painful joints. Both gout and pseudo gout may be accompanied by a fever. Gout and pseudo gout triggers that are alike are joint injuries, and perhaps transplants. They have similar names probably because of the pain, inflammation and joint stiffness both cause. Their similarity may cause confusion in the correct diagnosis of both gout and pseudo gout.
But there are significant differences. Pseudo gout crystals are made from a different substance to the MSU gout crystals, and they can usually be viewed on an X-ray machine whereas gout's MSU crystals cannot. (Although bones and joints damaged by gout can be).
For gout to be completely accurately diagnosed, the crystals need to be identified as MSU gout crystals using a special polarising (polarizing) microscope to examine removed synovial joint fluid. This method has not changed since the mid 19th century. No one has discovered a better one.
Gout crystals are needle shaped, but pseudo gout crystals are mainly rhomboid shaped. It takes some training and practice to tell the difference between the two types under a polarising (polarizing) microscope.
And it gets complicated when, as sometimes happens, deposited crystals in the synovial joint fluid are both gout and pseudo gout types. Pseudo gout is much more likely to develop in men and women equally, and who are over 65 years old. And worsen as they age.
Gout is likely to start in men between 40 and 60, and in women after the menopause, (although it too may worsen as patients age). MSU gout crystals are largely made from uric acid, whereas pseudo gout crystals are made from calcium pyrophosphate dihydrate.
Gout and pseudo gout attacks too have a difference in their nature. Gout attacks usually develop quickly, often during the night, and reach maximum swelling within 12-24 hours. Pseudo gout attacks usually build up over a number of days and are normally less severe than gout attacks.
Gout's immediate cause is that uric acid forms crystals, whereas pseudo gout's cause is unknown. Gout frequently starts in the joints of one of the big toes, whereas pseudo gout may start in the knees but not usually the big toe joint.
Gout may be cured by lowering uric acid levels, or by the action of alkalizing agents. Or by another action of baking soda (bicarbonate of soda) apart from its effect as an alkalising (alkalizing) agent. And by natural remedies. Its cure involves dissolving crystals. Pseudo gout can be treated successfully, but not cured.
Gout's major long term causes i.e. abnormalities of purine metabolism, excessive purine intake and uric acid levels, insulin resistance and kidney disease, are not suspected to be pseudo gout's causes. Theories for pseudo gout causes include: osteoarthritis; cartilage injuries causing the release of calcium crystals into the joint; excessive iron for genetic reasons; an under active thyroid gland; and excessive blood (serum) calcium. These are all different to gout's long term causes.
PSEUDO GOUT TREATMENT
Pseudo gout is treated with NSAIDs, colchicine and sometimes, in severe cases, corticosteroids, just like gout. It may also be treated by joint aspiration (aka arthrocentesis) surgery to remove its crystals-saturated fluid, from the affected joint(s). These treatments usually work to relieve pain and inflammation but pseudo gout attacks can return, and over the longer term cause joint degeneration in serious cases, just like gout.
Obviously, pseudo gout does not require uric acid lowering meds like allopurinol, probencid or febuxostat (generic names) since uric acid has not caused it.
Unlike gout, tophi do not develop. Return attacks are usually treated successfully. However, in the end, surgery may be required to replace the affected joint(s) of pseudo gout.
If you've read around this site you'll know there's much you can do to prevent gout, which always involves lowering uric acid. With pseudo gout, this is not the case.
If you get both, your doctor will probably recommend dealing with gout first, since it can be dealt with more easily, it causes more pain, and because gout causes tophi, whereas pseudo gout does not. Tophi, in the end, and this takes years without successful treatment, can destroy bones, joints, tendons and cartilage.