Gout is a common form of inflammatory arthritis, characterized by sudden, severe attacks of joint pain. These attacks often include redness, swelling, and warmth in the affected joint, most commonly the big toe. Gout can also affect other joints like the ankles, knees, wrists, and fingers. Several other conditions are frequently mistaken for gout.
Conditions Affecting Joints
Several forms of arthritis or joint issues can mimic the acute, painful inflammation seen in gout. Pseudogout is caused by the deposition of calcium pyrophosphate crystals, rather than the uric acid crystals responsible for gout. While symptoms are similar, pseudogout often affects larger joints such as the knee or wrist, rarely the big toe. A pseudogout flare can last days, weeks, or even months if untreated.
Septic arthritis, a serious joint infection, also presents with rapid, severe pain, swelling, and redness, often accompanied by fever. This condition requires immediate medical attention due to the risk of joint damage. Septic arthritis typically affects one joint, most often the knee, hips, or ankles, and can be a complication of gout.
An acute flare-up of rheumatoid arthritis (RA) can also be confused with gout. While RA typically involves chronic, symmetrical inflammation in multiple joints, a sudden exacerbation can cause intense pain and swelling in a single joint. Osteoarthritis (OA), a degenerative joint disease, can have acute inflammatory flares. Although OA pain is usually more gradual, a flare can cause significant pain and swelling in a joint, though generally less severe or sudden than a gout attack.
Conditions Affecting Skin and Soft Tissues
Issues primarily affecting the skin or soft tissues around a joint can be mistaken for gout due to localized redness, swelling, and pain. Cellulitis, a bacterial skin infection, causes the skin to become red, swollen, tender, and warm. This infection can occur near a joint, leading to confusion with gout. Unlike gout, cellulitis requires antibiotic treatment.
Bursitis involves inflammation of a bursa, a small fluid-filled sac that cushions bones, tendons, and muscles near joints. When a bursa becomes inflamed, it can cause localized pain, swelling, and redness, particularly in areas like the elbow (olecranon bursitis) or knee (prepatellar bursitis). Although bursitis can mimic gout, it is an inflammation of the cushioning sac, not the joint itself.
Tendonitis, inflammation of a tendon, can also cause localized pain and swelling. Tendons are the connective tissues that attach muscles to bones. While tendonitis typically results in pain and soreness around the affected joint, the widespread redness seen in gout is often less pronounced.
Distinguishing Features and Medical Diagnosis
Distinguishing gout from its mimickers involves noting specific symptom characteristics. Gout attacks are typically sudden, excruciatingly painful, and make the affected joint hot, swollen, and tender to touch, often in the big toe. Other conditions, like pseudogout, more frequently affect larger joints, while cellulitis shows skin infection extending beyond the joint.
A definitive medical diagnosis is crucial for effective treatment. Doctors typically begin with a detailed medical history and a physical examination of the affected joint. Joint fluid analysis is considered the most accurate way to diagnose gout and pseudogout. This involves drawing fluid from the painful joint and examining it under a microscope for specific crystals: uric acid crystals for gout or calcium pyrophosphate crystals for pseudogout.
Blood tests may also be ordered, including checking uric acid levels, though high levels do not always indicate gout, and normal levels do not rule it out. Inflammatory markers like C-reactive protein (CRP) can also be assessed. Imaging techniques like X-rays, ultrasound, and dual-energy computed tomography (DECT) can provide additional information. Ultrasound can detect urate crystals and specific signs like the “double contour sign,” while DECT can visualize crystal deposits. Accurate diagnosis is essential to ensure the correct treatment and prevent potential complications.