What are the results of the uric acid laboratory tests (Uric Acid Labs)?

From the Guidelines

Uric acid labs should be ordered when evaluating for gout, kidney stones, or monitoring treatment for hyperuricemia, with a target uric acid level below 6.0 mg/dL for gout management. The normal range for serum uric acid is typically 3.5-7.2 mg/dL for men and 2.6-6.0 mg/dL for women, though reference ranges may vary slightly between laboratories 1. When testing, patients should fast for at least 8 hours beforehand and avoid alcohol for 24 hours, as these can affect results. Certain medications like diuretics, aspirin, and niacin can elevate uric acid levels, so medication history should be considered when interpreting results. For gout management, regular monitoring every 2-4 weeks is recommended when initiating urate-lowering therapy like allopurinol (starting at 100mg daily and titrating up) or febuxostat (40-80mg daily) 1. Elevated uric acid occurs when the body either produces too much uric acid or the kidneys cannot effectively excrete it, leading to crystal deposition in joints causing gout, or formation of kidney stones. In patients with recurrent gout attacks or kidney stones, 24-hour urine collection for uric acid may help determine if the hyperuricemia is due to overproduction or underexcretion, which guides treatment decisions 1.

Some key points to consider when ordering uric acid labs include:

• The patient's medical history, including any medications that may affect uric acid levels
• The patient's symptoms, such as joint pain or kidney stones
• The need for regular monitoring when initiating urate-lowering therapy
• The importance of maintaining a target uric acid level below 6.0 mg/dL for gout management

It's also important to note that the American College of Physicians recommends using synovial fluid analysis when clinical judgment indicates that diagnostic testing is necessary in patients with possible acute gout 1. Additionally, the European League Against Rheumatism recommends maintaining the serum uric acid below the saturation point for monosodium urate (360 mmol/l or 6 mg/dl) to promote crystal dissolution and prevent crystal formation 1.

From the FDA Drug Label

The upper limit of normal is about 7 mg/dL for men and postmenopausal women and 6 mg/dL for premenopausal women. Normal serum urate levels are usually achieved in 1 to 3 weeks The correct dosage and schedule for maintaining the serum uric acid within the normal range is best determined by using the serum uric acid as an index.

The target serum uric acid level is 6 mg/dL or less.

• Normal serum urate levels are usually achieved in 1 to 3 weeks.
• The upper limit of normal is about 7 mg/dL for men and postmenopausal women and 6 mg/dL for premenopausal women 2.
• The correct dosage and schedule for maintaining the serum uric acid within the normal range is best determined by using the serum uric acid as an index 2.

From the Research

Uric Acid Labs

• Uric acid labs are used to measure the level of uric acid in the blood, which is an important indicator of gout and hyperuricemia 3, 4, 5, 6, 7
• The normal range for uric acid in the blood is typically considered to be between 3.5 and 7.2 mg/dL for men and between 2.6 and 6.0 mg/dL for women 3, 4
• Elevated uric acid levels can indicate gout, hyperuricemia, or other conditions such as kidney disease or certain types of cancer 6, 7

Treatment of Hyperuricemia

• Allopurinol and febuxostat are two commonly used medications for the treatment of hyperuricemia and gout 3, 4, 5, 6, 7
• Febuxostat has been shown to be more effective than allopurinol in lowering serum urate levels in some studies 3, 4
• However, other studies have found that allopurinol and febuxostat have similar efficacy in achieving target serum urate levels 5

Renal Outcomes

• Patients with chronic kidney disease (CKD) are more likely to develop hyperuricemia and gout, and require careful management of uric acid levels 6
• Febuxostat may be more renoprotective than allopurinol in patients with both hyperuricemia and CKD, although more studies are needed to confirm this finding 6

Laboratory Measurements

• Serum urate concentration is typically measured using a laboratory test, and is an important indicator of gout and hyperuricemia 3, 4, 5, 6, 7
• Other laboratory measurements, such as creatinine and estimated glomerular filtration rate (eGFR), may also be used to monitor kidney function in patients with hyperuricemia and CKD 6