False Gout: Understanding Pseudogout, Causes, Symptoms, Diagnosis, and Treatment

What is False Gout?

False gout, medically known as pseudogout or Calcium Pyrophosphate Deposition (CPPD) disease, is a form of arthritis characterized by sudden, painful swelling in one or more joints, caused by the deposition of calcium pyrophosphate dihydrate crystals within the joint cartilage.

Understanding False Gout: An Overview

False gout, or pseudogout, is a crystalline arthropathy that mimics the symptoms of true gout but is caused by a different type of crystal. While true gout is associated with uric acid crystal deposits, false gout results from the accumulation of calcium pyrophosphate dihydrate (CPPD) crystals in the cartilage and synovial fluid of joints. These crystals can trigger an inflammatory response, leading to acute, painful episodes. The term "pseudogout" directly translates to "false gout" because of its striking resemblance to the more common condition.

Causes of False Gout

Unlike true gout, which is strongly linked to diet and purine metabolism, the exact cause of CPPD crystal formation and deposition in pseudogout is not fully understood. However, several factors are known to increase the risk:

• Aging: The prevalence of CPPD deposits increases significantly with age, suggesting a link to cartilage degeneration over time.
• Joint Trauma or Surgery: Injury to a joint can sometimes trigger CPPD crystal formation or release, leading to an acute attack.
• Genetic Predisposition: There appears to be a hereditary component in some cases, with certain families having a higher incidence of the condition.
• Metabolic Disorders: Pseudogout is often associated with other medical conditions, including:
  • Hypomagnesemia: Low levels of magnesium in the blood.
  • Hyperparathyroidism: Overactive parathyroid glands.
  • Hemochromatosis: Iron overload disorder.
  • Hypothyroidism: Underactive thyroid gland.
  • Gout: Interestingly, some individuals can have both CPPD and uric acid crystals.
  • Osteoarthritis: Degenerative joint disease is commonly seen alongside CPPD.

Symptoms of False Gout

An attack of false gout typically presents with acute and severe symptoms, often developing rapidly over hours:

• Intense Joint Pain: The hallmark symptom, often severe enough to be debilitating.
• Swelling: Significant accumulation of fluid around the affected joint.
• Redness: The skin over the joint may appear flushed or red due.
• Warmth: The affected joint feels hot to the touch.
• Tenderness: Even light pressure on the joint can cause extreme pain.
• Limited Range of Motion: Due to pain and swelling, movement of the joint becomes restricted.
• Fever: In some cases, a low-grade fever may accompany the joint inflammation.

Episodes can last for days or even weeks, varying in intensity. While acute attacks are common, some individuals may experience chronic pain and stiffness due to ongoing crystal deposition and inflammation, resembling osteoarthritis.

Joints Commonly Affected

While false gout can affect any joint, certain areas are more frequently involved:

• Knees: The most common site for pseudogout attacks, often presenting with significant swelling and pain.
• Wrists: Another frequent target, leading to difficulty with hand movements.
• Shoulders: Can cause severe pain and limit arm mobility.
• Ankles: Similar to knees, can cause significant pain and difficulty with weight-bearing.
• Elbows: Less common than knees or wrists, but can still be affected.
• Hips: Can lead to deep, aching pain and impaired walking.
• Spine: Though less common for acute attacks, CPPD can deposit in spinal ligaments, causing chronic pain and stiffness.

Unlike true gout, which famously targets the big toe, pseudogout rarely affects this joint.

Differentiating False Gout from True Gout

Given their similar presentation, distinguishing between false gout and true gout is crucial for appropriate treatment. Key differences include:

• Crystal Type:
  • False Gout: Caused by calcium pyrophosphate dihydrate (CPPD) crystals.
  • True Gout: Caused by monosodium urate (MSU) crystals (uric acid).
• Joint Predilection:
  • False Gout: Most commonly affects knees, wrists, shoulders, and other large joints.
  • True Gout: Most commonly affects the big toe (podagra), though it can affect other joints.
• Crystal Shape under Microscope:
  • False Gout: CPPD crystals are typically rhomboid-shaped (brick-like) and positively birefringent under polarized light microscopy.
  • True Gout: MSU crystals are typically needle-shaped and negatively birefringent.
• Associated Conditions:
  • False Gout: Often associated with aging, osteoarthritis, hyperparathyroidism, hypomagnesemia.
  • True Gout: Strongly associated with hyperuricemia (high uric acid levels), obesity, metabolic syndrome, kidney disease, certain medications, and diet high in purines.

Diagnosis of False Gout

Accurate diagnosis of false gout typically involves a combination of clinical evaluation, imaging, and laboratory tests:

• Joint Fluid Analysis (Arthrocentesis): This is the gold standard for diagnosis. A sample of synovial fluid is aspirated from the affected joint and examined under a polarized light microscope. The presence of rhomboid-shaped, positively birefringent CPPD crystals confirms the diagnosis. This analysis also helps rule out bacterial infection (septic arthritis), which can present similarly.
• Imaging Studies:
  • X-rays: Can reveal chondrocalcinosis, which is calcification of the cartilage, appearing as fine white lines within the joint space. This finding is highly suggestive of CPPD deposition but does not confirm an acute attack.
  • Ultrasound: Can show crystal deposits in cartilage and synovial membrane, as well as joint effusions.
  • CT Scan: Can provide more detailed images of crystal deposits and joint damage.
• Blood Tests: While not diagnostic for false gout, blood tests may be performed to check for underlying conditions associated with CPPD, such as magnesium levels, parathyroid hormone levels, iron levels, and thyroid function. Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP) may be elevated during an acute attack, indicating inflammation.

Management and Treatment

Treatment for false gout primarily focuses on managing acute attacks and preventing future episodes. There is no cure for CPPD disease, as the crystals cannot be dissolved like uric acid crystals in true gout.

• Acute Attack Management:

  • Nonsteroidal Anti-inflammatory Drugs (NSAIDs): Medications like ibuprofen, naproxen, or indomethacin are often the first line of treatment to reduce pain and inflammation.
  • Corticosteroids: Oral corticosteroids (e.g., prednisone) or corticosteroid injections directly into the affected joint can provide rapid relief for severe attacks or when NSAIDs are contraindicated.
  • Colchicine: Can be used to reduce inflammation during an acute attack, similar to its use in true gout, or sometimes in low doses as a preventative measure.
  • Joint Aspiration: Removing excess fluid from the joint can help relieve pressure and pain.
  • Rest and Ice: Resting the affected joint and applying ice packs can help reduce swelling and discomfort.

• Long-Term Management:

  • Treating Underlying Conditions: Managing any associated metabolic disorders (e.g., hyperparathyroidism, hemochromatosis) may help reduce the frequency of attacks.
  • Physical Therapy: For chronic cases, physical therapy can help maintain joint function and mobility.
  • Pain Management: For persistent pain, other pain relief strategies may be necessary.

Prognosis and Long-Term Outlook

The prognosis for individuals with false gout varies. Acute attacks are typically self-limiting, resolving within days to weeks, but they can be very painful and debilitating. The long-term outlook depends on the frequency and severity of attacks, as well as the extent of crystal deposition and associated joint damage.

In some cases, chronic CPPD deposition can lead to persistent pain, joint stiffness, and degenerative changes that resemble osteoarthritis, sometimes referred to as "pseudogout arthropathy." While there is no way to dissolve the crystals, effective management of symptoms can significantly improve quality of life and preserve joint function.

When to Seek Medical Attention

It is important to seek medical attention if you experience:

• Sudden, severe joint pain and swelling, especially if accompanied by redness and warmth.
• Symptoms that do not improve with over-the-counter pain relievers.
• Recurrent episodes of joint inflammation.
• Fever along with joint pain, which could indicate an infection.

Early and accurate diagnosis is essential to differentiate false gout from other forms of arthritis, including true gout and septic arthritis, ensuring appropriate and timely treatment.