Pseudogout

Overview

Pseudogout, also called calcium pyrophosphate deposition disease (CPPD), is a type of arthritis caused by the buildup of calcium pyrophosphate crystals in and around a joint. When these crystals shed into the joint space, they can trigger sudden, painful inflammation. The condition gets its name because its attacks closely resemble gout, although gout is caused by a different crystal (uric acid).

Pseudogout most often affects the knee but can also involve the wrists, shoulders, and other joints. It becomes more common with age. Attacks can come on quickly and be quite painful, but they are treatable, and the inflammation can be controlled with medication.

Symptoms

Symptoms typically appear as sudden attacks affecting one joint at a time:

• Sudden, intense pain in a joint, often the knee
• Swelling, warmth, and redness over the joint
• Tenderness that makes movement and weight-bearing difficult
• Attacks that last from several days to a couple of weeks

Between attacks, many people have no symptoms. Some develop a more chronic form that can resemble ongoing arthritis with persistent stiffness and aching. A hot, swollen, painful joint with fever should be evaluated promptly, as a joint infection must be ruled out.

Causes

Pseudogout occurs when calcium pyrophosphate crystals form in joint cartilage and then release into the joint:

• Crystal buildup with age: The tendency to form these crystals increases as people get older.
• Triggers: Attacks can be set off by joint injury, surgery, or serious illness.
• Underlying conditions: Certain metabolic and hormone disorders, such as overactive parathyroid glands, high iron, or low magnesium, are linked to crystal formation.

In many people, no specific underlying cause is found beyond age-related changes.

Risk Factors

• Older age
• Previous joint injury or joint surgery
• A family history of CPPD
• Metabolic conditions such as overactive parathyroid glands, excess iron (hemochromatosis), or low magnesium
• Existing osteoarthritis

Diagnosis

Diagnosis aims to confirm crystals and exclude other causes:

• Joint fluid analysis: Removing fluid from the joint and examining it under a microscope to find calcium pyrophosphate crystals and rule out infection or gout.
• Imaging: X-rays can show calcium deposits in the cartilage.
• Blood tests: Used to look for underlying metabolic conditions.

Treatment

Treatment focuses on relieving attacks and reducing inflammation. There is no medication that dissolves the crystals.

• Anti-inflammatory medicines: Nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and swelling during an attack.
• Colchicine: Can ease attacks and may be used to help prevent recurrent ones.
• Corticosteroids: Given by mouth or injected into the joint for severe attacks or when other drugs are not suitable.
• Joint drainage: Removing excess fluid can relieve pressure and confirm the diagnosis.
• Treating underlying conditions: Managing any associated metabolic disorder.

When to See a Doctor

See a doctor if you have sudden, severe joint pain and swelling, especially if it is new or recurrent. Seek prompt medical care for a hot, red, swollen, very painful joint, particularly if you also have a fever, because a joint infection (septic arthritis) is a medical emergency that can look similar to pseudogout and requires urgent treatment to protect the joint.

Related Topics

Frequently Asked Questions

References

1. Mayo Clinic. Pseudogout — Symptoms and causes.
2. MedlinePlus, U.S. National Library of Medicine. Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease.
3. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Gout and Pseudogout.
4. American College of Rheumatology. Calcium Pyrophosphate Deposition (CPPD).