Pseudogout (SOO-doe-gout) is a form of arthritis characterized by sudden, painful swelling in one or more of your joints. These episodes can last for days or weeks. The most commonly affected joint is the knee.

Also called calcium pyrophosphate deposition disease or CPPD, the common term "pseudogout" was coined for the condition's similarity to gout. Crystal deposits within a joint cause both conditions, although the type of crystal differs for each condition.

It isn't clear why crystals form in your joints and cause pseudogout, but the risk increases with age. Treatments can help relieve pain and reduce inflammation.

Pseudogout most commonly affects the knees. Less often, wrists and ankles are involved. In many cases, there are no symptoms. However, during a pseudogout attack, the affected joints are usually:

• Swollen
• Warm
• Severely painful

When to see a doctor

Make an appointment with your doctor if you have sudden, intense joint pain and swelling.

Pseudogout has been linked to the presence of calcium pyrophosphate dihydrate crystals within the affected joint. These crystals become more numerous as people age, appearing in nearly half the population older than age 85. But most people who have these crystal deposits never develop pseudogout. It's not clear why some people have symptoms and others don't.

Factors that can increase your risk of pseudogout include:

• Older age. The risk of developing pseudogout increases with age.
• Joint trauma. Trauma to a joint, such as a serious injury or surgery, increases your risk of pseudogout in that joint.
• Genetic disorder. In some families, a predisposition for developing pseudogout is hereditary. These people tend to develop pseudogout at younger ages.
• Mineral imbalances. The risk of pseudogout is higher for people who have excessive calcium or iron in their blood or too little magnesium.
• Other medical conditions. Pseudogout has also been linked to an underactive thyroid gland or an overactive parathyroid gland.

The crystal deposits associated with pseudogout can also cause joint damage, which can mimic the signs and symptoms of osteoarthritis or rheumatoid arthritis.

Pseudogout signs and symptoms can mimic those of gout and other types of arthritis, so lab and imaging tests are usually necessary to confirm a diagnosis.

Lab tests

Blood tests can check for problems with your thyroid and parathyroid glands, as well as for a variety of mineral imbalances that have been linked to pseudogout. Your doctor may withdraw a sample of the fluid from your affected joint with a needle to test for the presence of crystals.

Imaging tests

X-rays of your affected joint often can reveal joint damage and crystal deposits in the joint's cartilage.

There's no cure for pseudogout, but a combination of treatments can help relieve pain and improve the joint's function.

Medications

If over-the-counter pain relievers aren't enough, your doctor may suggest:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). Prescription strength NSAIDs include naproxen (Anaprox, Naprosyn, others) and indomethacin (Indocin). NSAIDs can cause stomach bleeding and decreased kidney function, especially in older adults.
• Colchicine (Colcrys). Low-dose pills of this gout drug are also effective for pseudogout. If you have frequent episodes of pseudogout, your doctor may recommend that you take colchicine daily as a preventive measure.
• Corticosteroids. If you can't take NSAIDs or colchicine, your doctor may suggest taking corticosteroid pills, such as prednisone, to reduce inflammation and end the attack. Long-term use of corticosteroids can weaken bones and cause cataracts, diabetes and weight gain.

Joint drainage

To relieve pain and pressure in an affected joint, your doctor inserts a needle and removes some of the joint fluid, which helps remove some of the crystals from the joint. The doctor will then inject the joint with a numbing medication and a corticosteroid to decrease inflammation.

Home treatments may be useful during pseudogout flare-ups. Examples include:

• NSAIDs. Over-the-counter NSAIDs, such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve), often are helpful.
• Rest the joint. Try not to use the affected joint for a couple of days.
• Ice. Cold packs can help reduce the inflammation associated with flare-ups.

You'll probably first see your family doctor. After an initial examination, your doctor may refer you to a specialist in the diagnosis and treatment of arthritis and other inflammatory joint conditions (rheumatologist).

Here's some information to help you get ready for your appointment.

What you can do

Before your appointment, you may want to write a list of answers to the following questions:

• When did your symptoms begin?
• Have you had these symptoms before?
• Does any activity or position make your joint feel better or worse?
• Have you ever injured this joint?
• Do you have any other medical conditions?
• Has anyone in your family had joint problems?
• What medicines or supplements do you take regularly?

What to expect from your doctor

A doctor who sees you for symptoms common to pseudogout may ask a number of questions, such as:

• What are your symptoms?
• What part or parts of your body are affected?
• Do your symptoms come and go?
• How long do symptoms last?
• Have your symptoms worsened over time?
• Does anything seem to trigger your symptoms, such as certain foods or stress?
• Have you tried any treatments? Has anything helped?