What should be checked for gout?

If redness, swelling and pain occur in the joints and are relieved after rest, it is mostly considered to be gouty arthritis. Therefore, you can go to the hospital for comprehensive examinations such as blood uric acid and urate tests, imaging and ultrasound to determine whether you have gout. Drink more water in normal times, try to control your weight and don't be too fat.

1. Serum uric acid measurement

Hyperuricemia is defined as a blood uric acid level of more than 7 mg/dl for men and more than 6 mg/dl for women.

2. Urine uric acid determination

After 5 days of a low-purine diet, 24-hour urine uric acid excretion > 600 mg indicates excessive uric acid production (accounting for about 10%); < 300 mg indicates reduced uric acid excretion (accounting for about 90%). Under normal dietary conditions, 24-hour uric acid excretion is divided into 800 mg. Exceeding the above level means increased uric acid production. This examination is more necessary for patients with a family history of gout, younger age, significantly elevated blood uric acid levels, and kidney stones. Through testing, the biochemical typing of hyperuricemia can be preliminarily determined, which helps in selecting uric acid-lowering drugs and determining the nature of urinary stones.

3. Urate test

Polarized light microscopy reveals negatively birefringent needle- or rod-shaped monosodium urate crystals. During the acute attack phase, it can be seen inside and outside the white blood cells in the synovial fluid of the joints; it can also be seen in the aspirate of tophi; during the interval between attacks, it can also be seen in the synovial fluid of the affected joints.

4. Imaging examination

During the acute attack period, only asymmetric soft tissue swelling around the affected joints is seen; some atypical radiological changes may occur during the intervals between repeated attacks; during the chronic tophi lesion period, monosodium urate crystal deposition may cause bone destruction under the articular cartilage, resulting in eccentric round or oval cystic changes, and even worm-like or perforated defects with clear boundaries. The adjacent bone cortex may bulge or tilt like a bone spur. In severe cases, the articular surface can be destroyed, causing joint subluxation or dislocation, or even pathological fractures; the cartilage can also be destroyed, resulting in interarticular narrowing and secondary degenerative changes and local osteoporosis.

5. Ultrasound examination

Ultrasound examination of the affected joints can reveal joint effusion, synovial hyperplasia, articular cartilage and bone destruction, tophi and calcium deposits in the soft tissues within or around the joints. The presence of scattered strong echo spots in the renal medulla, especially in the pyramidal papillae under ultrasound indicates urate nephropathy. Uric acid urinary stones that are not visible under X-rays may also be detected.

6. Other laboratory tests

Urate nephropathy may have poor urine protein concentrating function, urine specific gravity below 1.008, and may eventually progress to azotemia and uremia.