A. Presence of characteristic urate crystals in the joint fluid, or

B. Presence of a tophus proven to contain urate crystals by chemical means or polarized light microscopy, or

C. Presence of six of the following clinical, laboratory, and radiographic phenomena:

1. More than one attack of acute arthritis.

2. Development of maximal inflammation within 1 day.

3. Attack of monarticular arthritis.

4. Observation of joint redness.

5. Pain or swelling in first metatarsophalangeal joint.

6. Unilateral attack involving first metatarsophalangeal joint.

7. Unilateral attack involving tarsal joint.

8. Suspected tophus.

9. Hyperuricemia.

10. Asymmetric swelling within a joint on x-ray.

11. Subcortical cysts without erosions on x-ray.

12. Negative culture of joint fluid for microorganisms during attack of joint inflammation.

Comparison of Gout and Pseudogout

	Gout	Pseudogout
Ratio of men to women	7:1	1:1.5
Age group affected	Men >40 years old Postmenopausal women	Elderly
Serum urate	Elevated	Normal
Joints involved	First metatarsophalangeal (MTP) joint, insteps, knees, wrists, fingers, olecranon bursae	Knees, wrists, ankles
Involvement of first MTP (podagra)	Common	Rare
Tophi	Present	Rare tophi-like deposits
Radiographic findings	Erosions with overhanging edges	Chondrocalcinosis
Crystals	Needle-shaped, strong negative birefringence	Rhomboid-shaped, weakly positive birefringence