Uric Acid

1️⃣ Hyperuricemia (↑ Uric Acid)

Defined as serum uric acid > 7 mg/dL in men.

A. Gout

• Deposition of monosodium urate crystals in joints
• Acute inflammatory arthritis
• Commonly affects the great toe (podagra)
• Chronic cases → tophi formation

B. Renal Disorders

• Uric acid kidney stones
• Acute uric acid nephropathy
• Chronic kidney disease (impaired excretion)

C. Hematological Disorders

Seen in conditions with high cell turnover:

• Leukemia
• Lymphoma
• Polycythemia
• Tumor lysis syndrome

D. Metabolic Syndrome & Cardiovascular Disease

Associated with:

• Hypertension
• Obesity
• Type 2 diabetes
• Increased cardiovascular risk

(Association; causality not fully established.)

E. Genetic Disorders

• Lesch-Nyhan syndrome (HGPRT deficiency)
• Increased purine synthesis → severe hyperuricemia

2️⃣ Hypouricemia (↓ Uric Acid)

Less common.

Causes include:

• Severe liver disease
• Fanconi syndrome
• SIADH
• Allopurinol therapy
• Xanthinuria

Mechanisms of Hyperuricemia

Overproduction

• High purine diet
• Malignancy
• Enzyme defects

Underexcretion (Most Common Cause)

• Renal impairment
• Diuretics
• Lead nephropathy