Gout laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
A definitive diagnosis of gout is made from light microscopy of the fluid aspirated from the joint. The fluid demonstrates intracellular negatively bi-refringent monosodium urate crystals and polymorphonuclear leukocytes in the synovial fluid. Although hyperuricemia is a common feature of gout, a high uric acid level does not necessarily mean a person will develop gout.
Laboratory Findings
While synovial fluid analysis remains the central pillar of diagnostic work up for all patients with new-onset acute monoarthritis, other laboratory investigations contribute to assist the diagnosis of gout, and in assessing comorbid conditions which affect gout.
| Sensitivity | Specificity | |
|---|---|---|
| > 5.88 mg/dl[1] | 95% | 53% |
| ≥ 6 mg/dl[2] | 86% | ? |
| ≥ 8 mg/dl[2] | 68% | ? |
Serum uric acid concentrations[3]
- Uric acid level is only useful to assist with clinical diagnosis of gout in symptomatic individuals as hyperuricemia alone is not sufficient.
- It is less significant in diagnosing gout, especially during an acute attack when urate excretion through the kidneys is often increased.
- The levels are important during urate lowering therapy when the goal is to maintain a target urate level.
Blood tests:
- Acute phase reactants, such as C-reactive protein, are usually increased during a flare—concentrations can be higher than 100 mg/L.[4]
- Complete blood counts showing neutrophil leukocytosis can also be present depicting degree of systemic inflammation.[5]
Renal function tests
- Renal function tests are recommended when prescribing and monitoring drugs used for urate lowering therapy.
References
- ↑ 1.0 1.1 Janssens HJ, Fransen J, van de Lisdonk EH, van Riel PL, van Weel C, Janssen M (2010). "A diagnostic rule for acute gouty arthritis in primary care without joint fluid analysis". Arch Intern Med. 170 (13): 1120–6. doi:10.1001/archinternmed.2010.196. PMID 20625017.
- ↑ 2.0 2.1 2.2 Schlesinger N, Norquist JM, Watson DJ (2009). "Serum urate during acute gout". J. Rheumatol. 36 (6): 1287–9. doi:10.3899/jrheum.080938. PMID 19369457. Unknown parameter
|month=ignored (help) - ↑ Brauer GW, Prior IA (October 1978). "A prospective study of gout in New Zealand Maoris". Ann. Rheum. Dis. 37 (5): 466–72. PMC 1000277. PMID 718280.
- ↑ Roseff R, Wohlgethan JR, Sipe JD, Canoso JJ (October 1987). "The acute phase response in gout". J. Rheumatol. 14 (5): 974–7. PMID 2448456.
- ↑ Dalbeth N, Merriman TR, Stamp LK (October 2016). "Gout". Lancet. 388 (10055): 2039–2052. doi:10.1016/S0140-6736(16)00346-9. PMID 27112094.