Uric acid deposition in tissues occurs when serum uric acid exceeds which threshold in mg/dL?

• A. >3
• B. >6.8
• C. >9
• D. >12

Answer: (B)

Uric acid has limited solubility in physiological fluids, so crystals form once it becomes supersaturated. At body temperature and normal blood pH, the solubility limit of monosodium urate is about 6.8 mg/dL. When serum urate rises above this threshold, crystals can precipitate in joints and soft tissues, leading to deposition and gout/inflammatory arthritis. Values well below 6.8 mg/dL stay dissolved, while higher levels indicate hyperuricemia, with deposition risk increasing as you approach and exceed the solubility limit.