High uric acid in a blood test: what it means, gout risk and next steps

Lab Tests Online UK explains that uric acid is produced by the breakdown of purines, nitrogen-containing compounds found in the body in substances such as DNA and RNA. Purines also enter the circulation from some foods and drinks, including alcoholic drinks such as beer and wine. Most uric acid is removed by the kidneys and passed in urine, with the remainder leaving in the stool.

Versus Arthritis uses the term urate and notes that, on any day, about three-quarters of the urate in the body comes from the breakdown of purines produced within the body, with only about a quarter from food and drink. If the body makes too much, or the kidneys cannot get rid of enough, the level rises.

Lab Tests Online UK says higher than normal blood uric acid is called hyperuricaemia and may be caused by over-production or by the kidneys being unable to clear enough, and that the doctor needs to investigate further to find the cause. Over-production can be seen with some cancers and cancer treatment (chemotherapy) because of cell death, or rarely from an inherited tendency. Reduced excretion can be seen with chronic kidney disease, toxaemia of pregnancy and alcoholism.

The NHS lists factors that raise the chance of gout, which are also factors that raise urate: being overweight, drinking alcohol, the menopause, medicines such as diuretics and some blood pressure medicines (ACE inhibitors), high cholesterol, high blood pressure, kidney problems, osteoarthritis and diabetes, and having had surgery or an injury. It adds that gout is more common in men, especially as they get older.

Versus Arthritis describes gout as a painful form of arthritis caused by uric acid crystals that form in and around the joints, occurring in people who have high levels of urate in their blood. The NHS says the main symptoms are sudden severe pain in a joint, usually the big toe, with hot, swollen, red skin over the joint, and that an attack usually lasts 1 to 2 weeks if left untreated.

The result needs careful interpretation. Lab Tests Online UK stresses that serum levels should only be considered with other clinical features of gout since on its own a level does not confirm or exclude the diagnosis; many patients with hyperuricaemia do not develop gout, while levels can be normal during an acute attack. That is why a GP may repeat the test between attacks, and why the NHS says that, if the test is unclear, a rheumatologist may arrange joint fluid sampling or a scan.

Lab Tests Online UK says that uric acid can form crystals or kidney stones that damage the kidneys and that urine uric acid may be requested when someone has recurrent kidney stones or has gout and needs monitoring for stone formation. The NHS lists kidney stones among the complications of long-term untreated gout. Reduced kidney function can also itself raise uric acid, so the two are often looked at together.

A high uric acid on a routine test in someone with no joint symptoms is common. Lab Tests Online UK notes that there has been discussion among doctors about the exact limits of a normal result, that the range seen in healthy people is wide and that levels vary from day to day, so several tests over time may be requested. A GP will usually look for contributing factors such as medicines, kidney function, alcohol, weight and blood pressure rather than starting treatment on the number alone.

The NHS lifestyle advice for preventing gout applies as sensible general advice: lose weight if overweight but avoid crash diets, eat a healthy diet, have some alcohol-free days each week and try not to drink more than 14 units a week, drink plenty of fluids to avoid dehydration, exercise regularly and quit smoking.

The NHS says that if you have frequent gout attacks or high levels of uric acid in your blood you may need to take uric acid-lowering medicine, and that it is important to take it regularly even when you no longer have symptoms. Versus Arthritis says most of the damage and complications of gout can be stopped by medication to lower urate levels and a healthy diet and lifestyle.

Lab Tests Online UK describes British Society for Rheumatology guidance, accredited by NICE, that aims initially to reduce and maintain serum urate at or below 300 micromol/L, and later, once the person is symptom free, at or below 360 micromol/L. These are treatment targets for people with gout, not thresholds for deciding that every high result needs medicine.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have a sudden painful, swollen joint that is getting worse and you also have a very high temperature, feel hot, cold or shivery, or feel sick or cannot eat, because these can mean infection in the joint that needs urgent medical help. A hot swollen joint should not be assumed to be gout.

Uric acid is a standard blood test in NHS gout assessment and monitoring. Home and private health-check uric acid results are usable, but they do not replace a clinical assessment, because a high level without symptoms has a different meaning from a level taken during an attack.