Pseudogout (Calcium Pyrophosphate Crystal Deposition)

**Pseudogout** results from the deposition of calcium pyrophosphate dihydrate (CPPD) crystals in joint cartilage and synovial fluid. When these crystals shed into the joint space, they trigger an intense inflammatory response causing severe pain and swelling. The condition gets its name from the similarity to true [gout](/condition/gout) — but with crystals of a different composition. **Key Differences from True Gout:** | Feature | Pseudogout | True Gout | |---------|-----------|----------| | Crystal type | Calcium pyrophosphate dihydrate (CPPD) | Monosodium urate | | Crystal shape | Rhomboid, weakly positive birefringence | Needle-shaped, strongly negative birefringence | | Most affected joint | Knee | First MTP (big toe) | | Sex distribution | Equal | More men | | Onset speed | Sudden but slower than gout | Very rapid (hours) | | Age | Older (>60 typical) | Any age, especially 40-60 | | Triggers | Often spontaneous | Diet, alcohol, stress | | Underlying disease | Sometimes (metabolic) | Usually hyperuricemia | | Treatment | Anti-inflammatories | Anti-inflammatories + uric acid control | | Long-term medication | Limited options | Allopurinol, febuxostat | **Four Clinical Presentations:** **1. Asymptomatic CPPD (Most Common):** - Crystals present on imaging (chondrocalcinosis) - No symptoms - Very common in older adults (50%+ over 85) - May progress to symptomatic disease **2. Acute Pseudogout Attack:** - Sudden severe pain - Joint swelling, warmth, redness - Most commonly knee (50%+) - Single joint usually affected - Resembles true gout but slower onset **3. Chronic CPPD Arthropathy:** - Resembles osteoarthritis pattern - Affects unusual joints (wrist, shoulder, ankle) - Insidious progression over years - Multiple joints **4. Pseudo-Rheumatoid Presentation (5%):** - Multiple joints affected symmetrically - Morning stiffness - Can be mistaken for rheumatoid arthritis - Negative rheumatoid factor (typically) **Triggers for Acute Attacks:** - **Surgery** (especially knee, hip surgery) - **Trauma** - **Severe medical illness** - **Joint aspiration** - **Bisphosphonate administration** (paradoxically) - **Often spontaneous** without identifiable trigger **Associated Medical Conditions:** Pseudogout is associated with several systemic conditions in younger or atypical patients: - **Hyperparathyroidism** - **Hemochromatosis** (iron overload) - **Hypothyroidism** - **Hypomagnesemia** - **Wilson's disease** - **Alkaptonuria** - **Familial chondrocalcinosis** (genetic forms) When pseudogout occurs in younger adults (<55) or at unusual joints, screening for these underlying conditions is recommended.

## Root Causes **Pseudogout results from CPPD crystal deposition in joints, with multiple contributing factors:** **Primary Mechanism:** - Calcium pyrophosphate dihydrate crystals form in joint cartilage - Crystals shed into joint space - Trigger intense inflammatory response - Inflammation causes acute symptoms **Age-Related Factors (Most Common):** - **Aging cartilage** more susceptible to crystal formation - **Metabolic changes** with age affecting calcium/pyrophosphate balance - **Cumulative cartilage damage** - **Most cases are age-related** with no identifiable underlying disease - Strongly age-correlated — rare under 50 **Underlying Medical Conditions (Especially in Younger Patients <55):** *Hyperparathyroidism:* - Elevated parathyroid hormone affects calcium metabolism - Screening with PTH and calcium recommended *Hemochromatosis:* - Iron overload affects cartilage - Iron studies (ferritin, transferrin saturation) recommended *Hypothyroidism:* - Affects cartilage metabolism - TSH screening *Hypomagnesemia:* - Low magnesium associated with crystal formation - Often from medications or chronic illness *Other Rare Causes:* - Wilson's disease (copper accumulation) - Alkaptonuria (homogentisic acid) - Familial chondrocalcinosis (genetic) **Risk Factors:** *Strong Risk Factors:* - **Age >60** (most important factor) - **Previous joint trauma or surgery** - **Osteoarthritis** of the affected joint - **Underlying metabolic disease** (in younger patients) *Triggers for Acute Attacks:* - **Surgery** (especially knee, hip surgery) - **Trauma to the joint** - **Severe medical illness** (infection, MI) - **Hospitalization** - **Joint aspiration** itself - **Bisphosphonate administration** (paradoxical effect) - **Often no identifiable trigger** *Family History:* - Genetic forms exist - Some families show clustering - Genetic testing not routinely performed **Why Older Adults Are at Higher Risk:** - Accumulated cartilage damage - Metabolic changes - More medications and procedures - More underlying conditions - More likely to undergo joint surgery - More likely to experience triggers (illness, hospitalization)

## Treatment Strategies **Pseudogout treatment has two components: acute attack management and prevention/chronic management. There is NO cure — focus is on symptom control.** ## Acute Attack Treatment **First-Line Options:** *NSAIDs:* - **Naproxen** 500 mg twice daily - **Indomethacin** 50 mg three times daily - **Ibuprofen** 800 mg three times daily - Effective in 5-7 days - Watch for contraindications (kidney disease, ulcers, cardiovascular disease) - Often limited by side effects in older adults *Colchicine:* - **0.6 mg twice daily** during acute attack - **Effective in many patients** - Limited by GI side effects - Reduce dose in kidney impairment - Can be combined with NSAIDs *Intra-articular Corticosteroid Injection:* - **Most effective for single-joint disease** - Triamcinolone or methylprednisolone - **Must rule out infection first** with joint aspiration and culture - Symptoms improve within 24-48 hours - Particularly useful in older patients with NSAID contraindications *Oral Corticosteroids:* - **Prednisone 30-50 mg daily**, tapered over 7-10 days - Useful when other options contraindicated - Multiple joint involvement - Effective and well-tolerated short-term **Adjunctive Measures:** - **Rest** the affected joint - **Ice application** 15-20 minutes - **Elevation** if applicable - **Acetaminophen** for breakthrough pain - **Cane or walker** if knee affected - **Avoid weight-bearing** as tolerated ## Chronic Management **For Patients with Frequent Attacks (>3 per year):** *Prophylactic Colchicine:* - **0.6 mg once or twice daily** - Reduces attack frequency - Generally well-tolerated long-term - Adjust for kidney function *Low-Dose NSAIDs:* - **Daily low-dose NSAID** if tolerated - Consider gastric protection - Monitor renal function *Hydroxychloroquine:* - **200-400 mg daily** for chronic CPPD arthropathy - Some evidence for prevention - Particularly useful in inflammatory pattern - Monitor for retinal toxicity *Methotrexate:* - **For refractory cases** - Pseudo-rheumatoid pattern - Standard rheumatology monitoring required **No Treatment Reduces Crystal Deposition:** - Unlike [gout](/condition/gout) where allopurinol/febuxostat lower uric acid - **No medication available** to dissolve CPPD crystals - **No medication prevents** CPPD formation - Treatment focuses on **inflammation control** ## Treat Underlying Conditions **For Younger Patients or Atypical Presentations:** *Hyperparathyroidism:* - Parathyroidectomy if indicated - Treatment may reduce attacks *Hemochromatosis:* - Phlebotomy therapy - Iron chelation if needed *Hypothyroidism:* - Thyroid hormone replacement - May improve symptoms *Hypomagnesemia:* - Magnesium repletion - Address underlying cause ## Surgery (Rare) **Joint Replacement:** - **End-stage CPPD arthropathy** with severe joint damage - Same as for [osteoarthritis](/condition/osteoarthritis) - Acute pseudogout common postoperatively (paradoxically) - Excellent outcomes for replacement surgery **Synovectomy:** - Rare option - May reduce attacks in select cases - Limited evidence ## Prevention Strategies **Lifestyle:** - **Stay active** within tolerance - **Maintain healthy weight** - **Avoid joint trauma** when possible - **Manage comorbid conditions** **Hydration:** - Adequate hydration generally recommended - No specific dietary restrictions (unlike gout) **Surgical/Procedural:** - Discuss CPPD history with surgeon - Postoperative pseudogout prophylaxis sometimes used - Consider colchicine perioperatively for high-risk patients ## Treatment Pearls **1. Rule Out Infection First** - Joint aspiration essential for new acute monoarthritis - Septic arthritis can coexist or mimic - Antibiotics urgent if infection present **2. Don't Confuse with True Gout** - Joint aspiration with polarized microscopy is definitive - Different crystals require different long-term approaches - Uric acid lowering doesn't help pseudogout **3. Postoperative Attacks Common** - Especially after knee/hip surgery - Consider prophylaxis in high-risk patients - Manage promptly when they occur **4. Limited Long-Term Options** - No disease-modifying therapy currently available - Focus on managing acute attacks - Address underlying conditions in atypical cases **5. Older Patients Often Have Comorbidities** - NSAID contraindications common - Corticosteroid injection often preferred - Multiple medications require careful management ## Prognosis **Acute Attacks:** - Most resolve completely with treatment - 1-2 weeks duration - Recurrence common in 30-50% **Chronic Disease:** - Progressive joint damage possible - Quality of life can be significantly affected - Joint replacement effective when needed **Survival:** - Pseudogout itself doesn't affect survival - Associated conditions may have implications - Joint disease impact on overall function affects elderly mortality indirectly