Laboratory studies Synovial fluid: 12 浙医二院
12 浙医二院 Laboratory Studies Synovial fluid:
The sensitivity of a synovial fluid analysis for crystals is 84%, with a specificity of 100%. If gout remains a clinical consideration after negative analysis findings, the procedure can be repeated in another joint or with a subsequent flare Crystals may be absent very early in a flare. t. Strongly negative birefringent双折 射的, needle-shaped crystals diagnostic gout obtained from an acutely inflamed oint Gout. Needles of urate on polarizing microscopy偏光显微术 浙医二院
13 浙医二院 Gout. Needles of urate on polarizing microscopy偏光显微术 Gout. Strongly negative birefringent双折 射的, needle-shaped crystals diagnostic of gout obtained from an acutely inflamed joint The sensitivity of a synovial fluid analysis for crystals is 84%, with a specificity of 100%.If gout remains a clinical consideration after negative analysis findings, the procedure can be repeated in another joint or with a subsequent flare. Crystals may be absent very early in a flare
Laboratory studies Serum uric acid This is the most misused test in the diagnosis of gout. T he presence of hyperuricemia in the absence of sympto ms Is no of gout. In addition, as many as %o of patients with symptoms due to gout may have mal serum uric acid levels at the time of their attack 少only D/o of patients with hyperuricemia develop gout. Gout is diagnosed based on the discovery of als in the synovial fluid or soft tissues. o Asymptomatic hyperuricemia should generally not be tr eated. The correlates with risk or developing gout. The -year risk for developing gout is approximately 0. 6% if the level is less than 7. 9 mg/d %o if 8-8.9 mg/dL, and if higher than 14 浙医二院
14 浙医二院 Laboratory Studies Serum uric acid This is the most misused test in the diagnosis of gout. T he presence of hyperuricemia in the absence of sympto ms is not diagnostic of gout. In addition, as many as 10 % of patients with symptoms due to gout may have nor mal serum uric acid levels at the time of their attack.--- only 5-20% of patients with hyperuricemia develop gout. Gout is diagnosed based on the discovery of urate cryst als in the synovial fluid or soft tissues. Asymptomatic hyperuricemia should generally not be tr eated. The level of serum uric acid correlates with risk f or developing gout. The 5-year risk for developing gout is approximately 0.6% if the level is less than 7.9 mg/d L, 1% if 8-8.9 mg/dL, and 22% if higher than 9 mg/dL
Laboratory studies Uric acid in 24-hour urine sample d in 24 hours on a regular diet, these patient ci If patients excrete more than of uric a (approximately 10%o of patients with gout) requi re allopurinol instead of probenecid to reduce ur ic acid levels In patients in whom probenecid is contraindicate ed(eg, those with a history of enal insufficiency 15 浙医二院
15 浙医二院 Laboratory Studies Uric acid in 24-hour urine sample If patients excrete more than 800 mg of uric aci d in 24 hours on a regular diet, these patients (approximately 10% of patients with gout) requi re allopurinol instead of probenecid to reduce ur ic acid levels. In patients in whom probenecid is contraindicat ed (eg, those with a history of renal stones or r enal insufficiency)