Pseudogout is a form of arthritis that most often affects the knees, but can affect other joints. There are more than 200,000 cases of pseudogout in the United States every year. Pseudogout is sometimes called chondrocalcinosis or calcium pyrophosphate dihydrate deposition disease, or CPP.
Definition & Facts
Pseudogout gets its name because of its similarity to gout. Its name means "false gout." It is a collection of crystals in the joints, as is gout. However, in gout, the crystals are comprised of uric acid, and in pseudogout, the crystals are comprised of calcium pyrophosphate.
Also, gout usually affects the big toe and pseudogout more often affects the knee, although either of these conditions can affect any joint. Untreated pseudogout can result in joint degeneration, which can lead to permanent physical disability.
Symptoms & Complaints
There are often acute attacks which can last days or even weeks. During an attack, joints may be swollen, warm, and extremely painful. These attacks can come on very suddenly, causing the patient to think an injury has occurred.
The pain can be quite severe, possibly feeling like the joints are on fire. There are also some cases where the patient does not feel any pain at all until the condition is quite advanced.
Fever may occur. The patient may have trouble using the joint. Attacks are similar to gout attacks, but usually less severe. Very rarely, crystals may form in the soft tissues surrounding the joints, causing hard lumps.
The main cause of pseudogout is the presence of calcium pyrophosphate dihydrate crystals in the fluid surrounding the joints. The crystals develop in the cartilage, then move to the joint lining or fluid and can cause inflammation.
Nearly half of all people have these crystals by the age of 85, but most of them never develop the symptoms of pseudogout. There may be a genetic predisposition towards developing these types of crystals.
Severe illness, joint trauma, kidney dialysis, or surgery can cause one to develop pseudogout. Other risk factors include old age, a family history of pseudogout, excessive calcium in the blood, excessive iron in the blood, low magnesium levels in the blood, amyloidosis, an underactive thyroid gland, and an overactive parathyroid gland (hyperparathyroidism). Attacks can be precipitated by dehydration.
Diagnosis & Tests
When making a diagnosis, it is important to distinguish between pseudogout and other conditions that may cause similar symptoms. The symptoms are almost identical to gout and are very similar to other forms of arthritis.
X-rays or ultrasounds are usually the first step in making a diagnosis. The affected area is X-rayed to see if there are crystals in the fluid surrounding the joints. Usually a sample of fluid is taken from the joint so that the crystals can be analyzed, since gout and pseudogout symptoms are very similar, but the crystals that cause them are made of different materials.
A special microscope with polarized light is used to distinguish the calcium pyrophosphate dihydrate crystals of pseudogout from the uric acid crystals of gout.
Blood tests are also done to determine an underlying problem such as low magnesium levels in the blood, hypercalcaemia (too much calcium in the blood), hemochromatosis (too much iron in the blood), hypothyroidism, or hyperparathyroidism.
Treatment & Therapy
Pseudogout cannot be cured, because there is no treatment that can completely rid the body of the calcium pyrophosphate dihydrate crystals. The main goal of treatment is to reduce pain, swelling, and inflammation and to improve mobility of the joint.
The first line of treatment is usually to take nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen. These drugs can reduce pain and inflammation and are usually well tolerated, although they can irritate the digestive tract. They are available over-the-counter. If the attack is severe, a prescription-strength nonsteroidal anti-inflammatory drug such as indomethacin may be prescribed.
Corticosteroids are sometimes prescribed as well, although they can have side effects such as increased appetite, mood swings, ulcers, acne, and others. These side effects can usually be reduced by lowering the dosage.
Another drug that is sometimes used is a low dose of colchicine, a common treatment for gout. This medicine can reduce swelling and inflammation and can provide some relief, although it is not a pain reliever. Side effects can include diarrhea, vomiting, cramping, and abdominal pain.
Non-drug therapies include RICE (medicine) (rest, ice, compression, elevation) and physical therapy. A temporary splint may be used to reduce movement of the joint. Fluid can be removed from the joint to relieve the pressure and remove some of the crystals. This procedure would be followed by an injection of a corticosteroid to reduce inflammation.
The prognosis for pseudogout is usually very good. Once the inflammation is relieved, the pain and mobility of the joint should return to normal in a few days or weeks, unless it has been severely damaged. If the joints are badly damaged, surgery may be needed to replace or repair them. Patients may go months or even years between attacks, and have no symptoms at all.
Prevention & Prophylaxis
A daily low dose of colchicine may be prescribed to prevent the inflammation that may lead to a painful attack. Avoiding foods that promote inflammation, such as sugars, may be helpful, although there is no specific diet to prevent pseudogout. Drinking lots of water to stay properly hydrated may help mitigate the risk of having pseudogout.