What is pseudogout

Pseudogout is a type of arthritis caused by the deposition of calcium pyrophosphate crystals in cartilage and the tissue around the joint (often referred to as calcium pyrophosphate deposition disease). Pseudogout causes painful swelling (inflammation) in one or more of your joints. It can lead to joint damage if left untreated.

As the name suggests, pseudogout is not true gout, but often causes symptoms that closely resemble those of gout. However, gout typically affects the joint in the big toe. Pseudogout usually affects larger joints, such as your knees. Also, pseudogout is caused by the build up of calcium pyrophosphate dihydrate crystals in your joints, while gout is caused by a build up of uric acid.

Pseudogout commonly occurs in elderly women – patients are over 50. However, pseudogout can occur in men as well. There is no preference in terms of ethnicity. The incidence of pseudogout rises with age, and is rare before 30 years. A family history of pseudogout increases risk, as do prior joint injury or surgery, hyperparathyroidism and hemochromatosis.

The calcium pyrophosphate crystal deposits of pseudogout affect about 3% of people in their 60s and as many as 50% of people in their 90s. The release of the calcium pyrophosphate crystals into the joint fluid can attract white blood cells, leading to a painful attack. Attacks of acute (short-lasting) arthritis can occur after injury to the joint, after surgery, or without a clear reason.

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.

There is no way to predict the course of pseudogout in a particular person.

• In some recurrent acute attacks may be the norm with apparent normality between attacks.
• Other patients may progress and develop significant joint damage with impairment of function.

Crystals deposit in the cartilage (the tissue that cushions inside joints) and can damage the cartilage. The crystals also can cause inflammation that leads to joint pain, warmth and swelling.

In most cases, it is not clear why the crystals form, although crystal deposits clearly increase with age. Because the condition sometimes runs in families, genes likely play a role. Experts do not know how to prevent these crystals. If pseudogout is due to some other medical problem, treatment of that condition may sometimes prevent pseudogout from getting worse.

Pseudogout may be divided into a number of categories:

1. Sporadic – no apparent predisposing factors
2. Hereditary – there is a family history of the disease, symptoms tend to manifest earlier
3. Secondary – linked to a history of joint injury or certain metabolic conditions such as hyperparathyroidism, hemochromatosis, diabetes and hypothyroidism.

Figure 1. Pseudogout crystals

Pseudogout prognosis (outlook)

Prognosis is good for acute episodes of pseudogout, which usually improve over a period of 10 days or so. Currently it is not known how to prevent or reverse joint damage caused by chronic disease.

Some patients may progress and develop significant joint damage with impairment of function.

Treatment may offer symptomatic relief, however, there is unfortunately no treatment for arresting the progress of the disease.

Pseudogout vs Gout

Gout and pseudogout are two types of arthritis that result in sore joints. With these types of arthritis, crystals form in the joint, causing irritation that is sometimes also present in the tendons near the joint. Joints can become swollen, painful, and red.

Gout happens when uric acid builds up in your body. Uric acid comes from the breakdown of substances called purines. Purines are in your body’s tissues and in foods, such as liver, dried beans and peas, and anchovies. Normally, uric acid dissolves in the blood. It passes through the kidneys and out of the body in urine. But sometimes uric acid can build up and form needle-like crystals. When they form in your joints, it is very painful. The crystals can also cause kidney stones.

Crystals form when people make too much, or do not get rid of, uric acid. Genetics are the main factor in determining uric acid levels. However, some medicines can cause changes in uric acid levels, including medicine for high blood pressure, diuretics (water pills), some blood thinners, and a medicine called cyclosporine, which is used for patients who have had a transplanted organ. Eating meat, seafood, and alcohol can also raise uric acid levels. In addition, obesity, insulin resistance, high cholesterol, heart disease, hypothyroidism and kidney disease can be associated with with this type of arthritis. Episodes of this condition have been noted after injury or surgery, sometimes involving infection or the use of contrast for x-rays. Physical fitness seems to help with prevention.

Often, gout first attacks your big toe. It can also attack ankles, heels, knees, wrists, fingers, and elbows. At first, gout attacks usually get better in days. Eventually, attacks last longer and happen more often. In pseudogout (calcium pyrophosphate deposition disease), larger joints such as the knee or wrist are more commonly involved.

You are more likely to get gout if you:

• Are a man
• Have family member with gout
• Are overweight
• Drink alcohol
• Eat too many foods rich in purines

Gout can be hard to diagnose. Your doctor may take a sample of fluid from an inflamed joint to look for crystals. You can treat gout with medicines.

Figure 2. Uric acid crystals (gout)

Pseudogout causes

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.

Risk factors for pseudogout

Factors that can increase your risk of pseudogout include:

• Older than 70 years of age. The risk of developing pseudogout increases with age.
• A history of pseudogout in your family.
• 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 (hypothyroidism) or an overactive parathyroid gland (hyperparathyroidism).
• Dehydration
• Hyperparathyroidism (causing increased calcium in the blood),
• Myxoedema, diabetes mellitus,
• Decreased phosphate,
• Any arthritis,
• Too much iron in your blood (called hemochromatosis),
• Hyperthyroidism,
• Low magnesium levels in the blood (hypomagnesemia)
• Too much calcium in your blood (hypercalcemia)
• Gout
• Osteoarthritis.

Pseudogout complication

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

How can I prevent pseudogout flare ups?

Treatment can relieve the symptoms of pseudogout and slow or prevent damage to your joints. Unfortunately, no treatment can get rid of the crystal deposits that cause pseudogout. Taking low doses of colchicine may help to reduce your risk of future attacks. Your doctor can talk to you about the risks and benefits of taking this medicine.

If another condition, such as a thyroid problem, caused your pseudogout, treating that condition may help to make the symptoms of pseudogout less severe.

Pseudogout symptoms

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.

Pseudogout diagnosis

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.

The diagnosis is made by viewing positively birefringent crystals in fluid taken from the affected joint under a microscope. Calcification of the cartilage made be seen on x-ray.

• Full blood count: – may show a raised white cell count
• Radiology: The crystals in pseudogout are usually only visible on an x-ray, may show linear calcification parallel to the articular surfaces (in articular cartilage which is normally radiolucent – chondrocalcinosis) (see Figure 3 below). Note: Uric acid (gout) does not show up on x-rays
• Serum calcium: normal.
• 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.
• If needed, fluid from the joint can be removed with a needle to confirm the diagnosis.

Calcium pyrophosphate crystals often are found in the cartilage and even synovial fluids of older people who have no symptoms. Many people who have these crystal deposits will never have acute gout-like attacks or chronic arthritis. These crystals also are often present in people with osteoarthritis or coincidentally in other types of arthritis such as gout or joint infections.

Figure 3. Pseudogout knee x-ray (arrows showing calcium deposits in soft tissues plus chondrocalcinosis of the knee meniscal cartilage)

Pseudogout treatment

There’s no cure for pseudogout, but a combination of treatments can help relieve pain and improve the joint’s function. Hence treatment is mainly symptomatic with:

• NSAIDs. (non-steroidal anti-inflammatory drugs)
• Colchicine may be used. (used to prevent or treat attacks of gout)
• Aspiration of the joint will often relieve pain; and
• If infection is excluded – a steroid injection into the joint will also help.

Treatment often consists of removing the fluid from the joint, corticosteroid injections and anti-inflammatory drugs to reduce pain and swelling. Currently there is no known way of removing the crystals already present in the joint and tissues.

Home remedies

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.

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.

People with poor kidney function, who have a history of stomach ulcers and/or who are on blood thinners often cannot take NSAIDs. For these patients, it may help to have your doctor drain the joint fluid and inject a corticosteroid into the affected joint. To try to prevent further attacks, low doses of colchicine (a medicine used more often for gout) or NSAIDs may prove effective.

Other medicines may help some patients during severe attacks of calcium pyrophosphate crystal arthritis or with the less common chronic inflammation that these crystals can cause. These drugs include hydroxychloroquine (Plaquenil), methotrexate (Rheumatrex, Trexall, Otrexup, Rasuvo), or an “interleukin 1 beta antagonist” that can decrease inflammation, such as the biologic medicine anakinra (Kineret). Anakinra is approved by the government for treatment of rheumatoid arthritis.

Surgery to repair and replace damaged joints is an option in severe cases.

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.