PSEUDOGOUT

I. Pathophysiology/epidemiology

1. Intra-articular calcium pyrophosphate dihydrate crystal deposition
2. More common than gout in geriatric pts; occurs in 33% of pts over 75yo

II. Clinical features

1. Morning stiffness & fatigue occur
2. Acute flares are accompanied by fever
3. Flares are precipitated by stress: surgery, trauma, severe illness
4. 20% have elevated serum levels of uric acid
5. 5% have monosodium urate crystals in synovial fluid along with calcium pyrophosphate
6. Associated with: hyperparathyroidism, hemochromatosis, hypothyroidism, gout, hemosiderosis, and possibly DM & Wilson's disease
7. Types of attack

1. Type A: acute attack; 1-2 joints, often knee
2. Type B: "pseudorheumatoid": am stiffness, synovial thickening, pitting edema, decreased ROM; 10% have weak pos. RF
3. Types C/D: "pseudo-osteoarthritis": knees, wrists, MCP's, hips, spine, shoulder, elbows, ankles. Type C has inflammation, type D none.
4. Type E: "Lanthanic" (asymptomatic): CPPD deposition without sx; see chondrocalcinosis on XR
5. Type F: "pseudoneuropathic": extensive destruction of joint (us. knee) with Charcot-joint-type appearance but nl neuro exam. Pretty rare.

III. Lab findings

1. Elevated ESR
2. Nl CBC & serum chemistries
3. Usually nl RF; ANA
4. Joint aspiration shows blood-tinged fluid, rhomboid crystals with polarized phase contrast microscopy, WBC >20k & 90% PMNs
5. XR often shows chondrocalcinosis (punctate & linear calcifictions of cartilage); calcific deposits in tendons & bursae; subchondral cysts, bone & cartilage fragmentation & asymmetric osteophytes.

IV. Treatment

1. Treat any underlying disorder (see above)
2. NSAIDS are mainstay
3. Colchicine or intra-articular steroids with acute attacks
4. Dietary modification is not helpful