The uric acid test in the blood is a test of the amount of uric acid to help diagnose gout, monitor the treatment of gout, and people who have received chemotherapy or radiation.
What is uric acid?
Uric acid is a chemical compound which is a waste substance caused by the consumption of food that contains purine. Foods that are high in purines include red beef, pork, lamb, poultry, and animal offal, etc.
However, whenever the body produces too much uric acid or has too little uric acid removed from the body (decreased excretion), the level of uric acid in the blood will increase. As a result, it causes pain in the joints and bones, also known as gout.
Normal values of uric acid in the blood:
Men: 4.0 – 8.5 mg/dL
Women: 2.7 – 7.3 mg/dL
Children: 2.5 – 5.5 mg/dL
The critical value is more than 12 mg/dL.
Reasons why the uric value is higher than the normal value:
- excessive consumption of foods high in purines;
- The body’s production of uric acid increases on its own.
- The kidneys excrete less uric acid in the urine than usual.
- From various risk factors such as alcohol consumption, high blood pressure, etc.
- Diabetes, hyperlipidaemia
- The use of drugs to treat some diseases.
- Genetics (a family member has had gout before).
- Gender, with males being more at risk. Women usually start after menopause.
Reasons for lower uric acid values:
- Wilson’s disease is a genetic disorder that causes the body to store excessive amounts of copper, leading to kidney toxicity. This toxicity disrupts the normal function of the kidneys, causing them to release biochemical substances, including uric acid, uncontrollably into the urine. Consequently, this results in abnormally low levels of uric acid in the blood.
- Fanconi syndrome is a condition characterized by defective kidney function, often due to genetic causes. It can also result from the use of certain medications that damage the kidneys. This condition impairs the kidneys’ ability to reabsorb vital substances, such as amino acids and phosphate, leading to their excretion in the urine. As a result, uric acid levels in the blood drop abnormally low.
- Hormonal imbalances can inhibit the proper release of water by the kidneys, causing water retention (oedema). This dilution of blood reduces its concentration, including the levels of uric acid.
- Dietary habits can also lead to low uric acid levels. For instance, adopting a vegetarian or low-purine diet to intentionally reduce uric acid intake can cause blood uric acid levels to drop below normal.
- Medications can sometimes lower blood uric acid levels as a side effect. Examples include:
- Clofibrate, used to reduce blood lipids.
- Oestrogen replacement therapy in postmenopausal women.
- Warfarin, used to prevent or treat blood clots.
- Glucose-based solutions administered to patients unable to consume food orally.
Reasons for Higher-Than-Normal Uric Acid Levels
These can be categorized into two cases:
Case 1: Normal Kidney Function with Excessive Uric Acid Production
When the kidneys are functioning well but there is an abnormally high production of uric acid in the bloodstream, the uric acid levels in the blood can become elevated.
Possible causes include excessive consumption of purine-rich foods.
- Foods high in purines that should be limited or avoided are:
- Red meats: Beef, buffalo meat, pork, lamb, venison, etc.
- Animal offal: Especially liver.
- Seafood: Shellfish, crab, shrimp, mackerel, sardines, trout, herring, and caviar (both fresh and canned).
- Yeast-based foods and beverages: Beer, wine, marmite, and bread.
- Mushrooms.
- Vegetables: Cauliflower, acacia, citrus, neem flower, cactus tops, vegetable tops, and asparagus.
- Nuts: Various types.
Foods with Low Purine Content
- Foods with low purine levels that are recommended for regular consumption include:
- Grains and starches: Rice, corn, oats, flour.
- Protein sources: Eggs, tofu, skim milk, yogurt, butter.
- Snacks and beverages: Chocolate, tea, coffee.
- Vegetables: Those that are not young shoots (e.g., mature vegetables), cauliflower.
- Fruits: All kinds of fresh fruits.
- Cereals: Various types.
Causes of High Uric Acid Levels
- Abnormal purine production in the body:
- Purine compounds are essential components of DNA, making up about half of its structure.
- Extremely high uric acid levels in the blood, despite normal kidney function, may indicate cancer metastasis or conditions such as bone marrow cancer, multiple myeloma, or leukaemia.
- Haemolysis:
- The breakdown of red blood cells (haemolysis) releases nucleic acids into the bloodstream. These are converted into uric acid, leading to elevated blood uric acid levels.
- Muscle breakdown (rhabdomyolysis):
- Muscle breakdown releases substances, including uric acid, into the bloodstream.
- This can occur due to causes such as:
- Statin use: Cholesterol-lowering medications may cause muscle breakdown as a side effect.
- The substances released, including uric acid, are toxic to the kidneys, further exacerbating the problem.
- Lead poisoning:
- Prolonged exposure to lead can result in kidney and liver damage, contributing to increased uric acid levels.
- Other causes:
- Obesity.
- Psoriasis.
- High triglycerides (hypertriglyceridemia).
Case 2: Kidney Problems Despite Avoiding High-Purine Foods
Even when a person avoids foods high in purines, kidney problems can result in elevated uric acid levels in the blood.
- Chronic kidney disease (CKD):
- In CKD, the kidneys are less efficient at excreting waste products, including uric acid. This leads to the accumulation of uric acid in the bloodstream, resulting in higher-than-normal levels.
- As the body progresses toward kidney failure, the renal tubules (kidney filtering structures) lose their ability to filter waste into urine effectively.
- The buildup of waste products, including uric acid, in the blood may serve as an indicator of kidney dysfunction.
- May be caused by kidney stones (Nephrolithiasis):
This refers to stones that obstruct the flow of urine within the kidney itself or stones that block the passage of urine from the kidney to the bladder. When urine cannot flow smoothly, it significantly impacts the kidney’s ability to excrete waste properly. As a result, waste products, including uric acid, accumulate and reach high levels in the blood. Abnormally high uric acid levels in the blood may indicate the presence of kidney stones.
- Alcohol consumption:
- Alcohol accelerates liver activity, sending waste products, including uric acid, into the bloodstream.
- This process can overwhelm the renal tubules, reducing their efficiency and causing an abnormal increase in blood uric acid levels.
- Diabetic acidosis or starvation acidosis:
- In diabetic acidosis, excess sugar from diabetes, and in starvation acidosis, excess ketones from fasting, can block the kidney tubules.
- This blockage results in reduced excretion of uric acid, leading to higher levels in the bloodstream.
- Hypothyroidism (underactive thyroid):
- The thyroid gland regulates metabolism. When its activity is reduced, metabolism slows down, which can result in:
- Weight gain.
- Various metabolic disorders.
- A slowed metabolism may increase uric acid levels in the bloodstream, contributing to hyperuricemia (elevated uric acid levels).
- The thyroid gland regulates metabolism. When its activity is reduced, metabolism slows down, which can result in:
- This is especially important for pregnant women.
- It may be caused by receiving certain medications. Certain medications can cause blood uric acid levels to be higher than normal, such as aspirin, cyclosporin, thiazide, Levodopa, Ethambutol, nicotinic acid, vitamin C, alcohol, etc.
- Other causes such as obesity, hypertension, thyrotoxicity, dehydration, etc.
