What are the causes and treatment options for hyperuricemia (elevated uric acid levels) in a patient with potential underlying health conditions such as kidney disease, diabetes, or obesity?

Causes of Hyperuricemia

Primary Mechanisms

Hyperuricemia results from two fundamental mechanisms: impaired renal excretion of uric acid (the dominant cause) or excessive uric acid production, with the former accounting for the majority of cases. 1

Decreased Renal Excretion (Most Common)

• Impaired renal excretion is the dominant cause of hyperuricemia, occurring when the kidneys fail to adequately eliminate uric acid despite normal production rates. 1
• Genetic factors involving uric acid transporters, particularly URAT1 (urate transporter 1), play a critical role in idiopathic hyperuricemia by affecting renal urate handling. 1
• Uromodulin (UMOD) mutations cause familial juvenile hyperuricemic nephropathy, characterized by early-onset hyperuricemia and progressive renal failure. 1
• Chronic kidney disease of any etiology reduces uric acid clearance, creating a bidirectional relationship where hyperuricemia both results from and contributes to CKD progression. 2, 3

Increased Uric Acid Production (Overproduction)

• Uric acid overproduction occurs through increased purine biosynthesis, accelerated purine metabolism, or excessive dietary purine intake. 4
• Screen specifically for overproduction in patients with gout onset before age 25 or those with a history of kidney stones using 24-hour urine collection; values >1000 mg/day define overproduction. 5, 6, 4
• Rapid cell turnover in hematologic malignancies (acute and chronic leukemia, polycythemia vera, multiple myeloma) releases massive quantities of intracellular nucleic acids that are catabolized to uric acid. 4, 7
• Tumor lysis syndrome following chemotherapy causes acute, life-threatening uric acid overproduction from rapid cancer cell destruction. 8, 4

Secondary Causes Requiring Systematic Evaluation

Medications (Eliminate When Non-Essential)

• Thiazide and loop diuretics elevate serum urate by reducing renal excretion and should be discontinued when non-essential. 8, 5, 6, 4
• Niacin and calcineurin inhibitors similarly elevate serum urate and warrant discontinuation if medically appropriate. 5, 6, 4
• Low-dose aspirin (≤325 mg daily) modestly elevates serum urate but should not be discontinued for cardiovascular prophylaxis. 4

Dietary and Lifestyle Factors

• High-fructose corn syrup consumption increases uric acid synthesis, with 1 gram of fructose per kilogram of body weight raising serum uric acid by 1-2 mg/dL within 2 hours. 4
• Alcohol intake, particularly beer and spirits, increases uric acid production and reduces renal excretion with a dose-response relationship for gout flares. 5, 6, 4
• Purine-rich meats (red meat, organ meats) and seafood contribute to hyperuricemia through dietary purine load. 5, 6

Comorbid Conditions

• Heart failure patients develop hyperuricemia from loop diuretic use and renal dysfunction, with hyperuricemia conferring poor prognosis in this population. 8
• Chronic cyanotic heart disease causes abnormal urate clearance from reduced glomerular filtration rate and increased red blood cell turnover, occasionally leading to symptomatic gout. 8
• Diabetes, metabolic syndrome, obesity, and hypertension frequently coexist with hyperuricemia through mechanisms involving insulin resistance, mitochondrial oxidative stress, and impaired nitric oxide bioavailability. 2, 9, 3, 10
• Visceral fat accumulation due to overnutrition affects uric acid metabolism independent of genetic predisposition. 2

Clinical Approach to Identifying the Cause

Mandatory Initial Assessment

• Calculate estimated glomerular filtration rate (eGFR) to assess renal function, as this determines both the cause and management approach. 6
• Review and eliminate all non-essential medications that elevate serum urate, including thiazide and loop diuretics, niacin, and calcineurin inhibitors. 5, 6
• Screen for cardiovascular disease, heart failure, stroke, peripheral arterial disease, diabetes, obesity, hyperlipidemia, and hypertension. 6

Specific Testing for Overproduction

• Obtain 24-hour urine uric acid collection in patients with gout onset before age 25 or history of kidney stones to distinguish overproducers (>1000 mg/day) from underexcretors. 5, 6, 4
• This distinction is therapeutically critical: do not use uricosuric drugs in overproducers, as increasing urinary uric acid excretion will precipitate nephrolithiasis and renal damage. 4

Specialist Referral Indications

• Consider rheumatology referral for unclear etiology of hyperuricemia, refractory symptoms despite appropriate therapy, difficulty reaching target uric acid levels, or multiple adverse events from urate-lowering therapy. 5, 6

Pathophysiologic Consequences

• Hyperuricemia causes inflammasome activation, decreased nitric oxide bioavailability, and oxidative stress through both uric acid crystals and xanthine oxidoreductase-mediated reactive oxygen species. 2
• These mechanisms contribute to hypertension, chronic kidney disease, atherosclerotic cardiovascular disease, metabolic syndrome, and type 2 diabetes development. 2, 9, 3
• Hyperuricemia is a predictive factor for developing hypertension, coronary artery disease, left ventricular hypertrophy, atrial fibrillation, myocardial infarction, stroke, and heart failure. 9