-
Hyperuricemia:
- biochemical hallmark of gout is hyperuricemia, but not by itself diagnostic for gout;
- risk of gout increases with the degree and duration of hyperuricemia;
- more than 95% of pts w/ gout have primary hyperuricemia;
- these pts exhibit overproduction of endogenous urate regardless of dietary intake;
- pts w/ primary gout also have defect excreting urate;
- note that the presence hyperuricemia in a patient with arthritis does not necessarily establish the dx of gout;
- w/ serum urate concentrations of 9.0 mg per deciliter (540 µmol / lit), incidence of acute gout is only about 5 % / year;
-
Leukocytosis:
- there may be a left shift of immature PMNs & elevated
sed rate;
-
Synovial Fluid:
- synovial fluid leukocyte counts may approach counts seen in
septic arthritis;
- viscosity of synovial fluid is < that seen in septic or inflammatory arthritis;
-
crystals:
-
crystal examination of synovial fluid:
- needle-like intracellular & extracellular monosodium urate crystals are seen under compensated polarized light microscopy;
- crystals are brightly birefringent and have negative elongation
- dx is made by observing negatively birefringent, needle-shaped MSU crystals engulfed by PMNs;
-
Urine Analysis:
- note that the excretion rate of urate in these patients is usually within the normal range'
- references:
- Gutman AB, Yu TF. Renal function in gout. Am J Med 1957;23:600-22.
- Simkin PA. Uric acid excretion in patients with gout. Arthritis Rheum 1979;22:98-9.
