Pseudogout is an arthritis caused by calcium pyrophosphate crystals. It commonly occurs in older adults, often affecting the knee. The symptoms closely resemble gout, but patients do not have high uric acid levels in the blood.

What causes pseudogout?

This disease results from the deposition of calcium pyrophosphate crystals within the joint, especially in articular cartilage. When these crystals shed into the synovial fluid, they trigger acute inflammation. Risk factors for pseudogout include the following:

 

1. Age: Most common in adults over 60 and the strongest risk factor.
2. Endocrine and metabolic disorders, such as hyperparathyroidism, iron overload, magnesium deficiency, hypothyroidism, and hypercalcemia.
3. Joint injury or prior joint surgery.
4. Genetics.
5. Osteoarthritis: pseudogout is frequently found alongside osteoarthritis.

What are the symptoms of pseudogout?

Pseudogout can present in several ways. The most common patterns include:

 

1. Acute arthritis

– Sudden, severe joint pain with swelling, redness, warmth, and tenderness; limited range of motion. Symptoms develop rapidly within 1–2 days and can flare and subside like gout.
– Commonly affected joints: knee, wrist, hip, shoulder, ankle.

2. Other presentations

– Chronic polyarthritis (multiple joints).
– Incidental detection of cartilage calcification without symptoms.
– Chronic joint pain resembling osteoarthritis, or coexistence with osteoarthritis that accelerates joint degeneration.

 

How is pseudogout different from gout?

Pseudogout

 

• Crystal type: calcium pyrophosphate.
• Common joints: knee, wrist, shoulder, ankle.
• Risk factors: older age; endocrine and metabolic diseases.
• Targeted therapy: no crystal-dissolving medication.

Gout

 

• Crystal type: uric acid (monosodium urate).
• Common joints: first metatarsophalangeal joint of the big toe; ankle.
• Risk factors: hyperuricemia, high-purine diet, alcohol use, obesity.
• Targeted therapy: urate-lowering medications.

 

How is pseudogout diagnosed?

1. History and physical examination: acute joint pain, especially in older adults; examination for signs of joint inflammation.
2. Synovial fluid analysis: the most important diagnostic test. A needle is used to aspirate synovial fluid for polarized light microscopy to identify calcium pyrophosphate crystals, which are rhomboid in shape and show weakly positive birefringence (blue when aligned parallel).
3. X-ray: may reveal calcification in articular cartilage (chondrocalcinosis), often in the knee, wrist, hip, and pelvis.
4. Blood tests: to look for associated causes such as iron studies, parathyroid hormone, thyroid hormone, calcium, phosphate, and magnesium.

 

How is pseudogout treated?

The goals of treating pseudogout are to reduce inflammation and relieve acute pain, and to prevent recurrent flares over the long term.

 

1. Acute phase

• Rest the affected joint; cold compresses can help reduce pain and swelling.
• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen.
• Corticosteroids: if symptoms are severe or NSAIDs are contraindicated, the clinician may inject intra-articular steroids or prescribe a short oral course.
• Colchicine: can be used to treat pseudogout to reduce inflammation and help prevent recurrences.

2. Long-term management and flare prevention

• There is currently no medication that dissolves calcium pyrophosphate crystals.
• Low-dose colchicine to prevent frequent recurrences.
• Manage underlying risk factors, such as thyroid disease.
• Maintain a healthy body weight; physical therapy to preserve joint mobility.