Uric acid

Uric acid is a natural waste product formed when the body breaks down purines from food.

What is uric acid?

Purines are found in animal organs, beef, and alcoholic beverages like beer and liquor. When these foods are consumed, purines are metabolized into uric acid.

Typically, uric acid dissolves in the blood and is then excreted through urine. However, several factors can lead to increased production or decreased excretion of uric acid, causing elevated levels in the blood (known as hyperuricemia). This forms urate crystals, which can deposit in the skin, joints, and kidneys, leading to various medical conditions.

Uric acid plays a crucial role in diagnosing and treating conditions like gout and kidney stones. Blood uric acid levels are also used to monitor uric acid concentrations in cancer patients undergoing chemotherapy or radiation therapy. It also helps track the risk of urate deposits in the kidneys and assess the potential for kidney failure.

What are normal uric acid levels?

To measure blood uric acid levels, patients need a uric acid quantification test. This requires fasting for 4-8 hours and abstaining from medications, supplements, stimulants, and alcoholic beverages.

Level 1: Blood uric acid levels < 6.5 mg/dl (< 380 μmol/liter) are considered normal and safe.

Level 2: Blood uric acid levels between 6.5-7.2 mg/dl (380-420 μmol/liter) are considered acceptable.

Levels 3 and 4: Blood uric acid levels of 7.2-8.2 mg/dl (420-480 μmol/liter) and 8.2-10 mg/dl (480-580 μmol/liter), respectively, may present some signs of acute gout attacks. The frequency of these attacks increases with higher uric acid levels.

Levels 5 and 6: Blood uric acid levels of 10-12 mg/dl (580-700 μmol/liter) and > 12 mg/dl (> 700 μmol/liter) are commonly seen in chronic gout, where tophi (urate crystal deposits) have formed under the skin.

Medical conditions related to high uric acid

Gout

When blood uric acid levels exceed saturation, it crystallizes into sharp urate crystals that deposit in joints and soft tissues. This accumulation triggers an acute inflammatory response, causing swelling, heat, redness, and severe pain in the affected joints, particularly the big toe. If left uncontrolled, this can lead to permanent joint damage and the formation of tophi under the skin.

Kidney disease

High uric acid causes kidney disease through two main mechanisms. First, it directly deposits urate crystals in the kidney tissue, causing inflammation and damage to the renal tubules, leading to chronic kidney disease or kidney failure. Second, it indirectly contributes to kidney stones formed from urate crystals. These stones can obstruct the urinary tract, causing fluid buildup and reduced kidney function.

Symptoms of kidney stones include severe back or flank pain, blood in the urine, and frequent urination. If not detected and treated early, kidney stones can block urine flow, cause infections, and even lead to long-term kidney problems.

See also What happens when uric acid is high?

Risk factors

: Male gender

: Family history of gout or kidney stones

: Obesity

: High blood pressure

: Diabetes

: Kidney disease

: Use of certain medications (diuretics, low-dose aspirin)

: Unhealthy diet

Preventing high uric acid

: A healthy diet, such as limiting purine-rich foods and eating plenty of vegetables and fruits.