How to track your uric acid over time

Uric acid shows up on a lot of routine blood work, usually unremarked, until someone has a gout attack. Then it becomes a number with a target, checked every few weeks while a medication is adjusted and then for years after. It is a test where the trend is the whole point. A single value drawn during a flare can be normal, and a value inside the lab’s range can still be above the target your clinician is aiming for.

What uric acid measures

Uric acid is a waste product. Your body makes it when it breaks down purines, which come from your own cells as they turn over and from some foods and drinks, as MedlinePlus explains. In the blood it is mostly present as urate, and the two names are used for the same test.

Most of it leaves through the kidneys. A National Kidney Foundation workshop report puts the split at about two thirds through the kidneys and one third through the gut. That is why kidney function, and many drugs that act on the kidney, move the number.

The level matters because urate can crystallize. The 2020 American College of Rheumatology gout guideline uses 6.8 mg/dL as the line for hyperuricemia, and Schlesinger and colleagues call 6.8 mg/dL the saturation level for urate. Above it, crystals can form in and around joints, which is what causes gout. Many people with a high level never have an attack.

There is also a 24-hour urine uric acid test, used mainly when kidney stones are the question. This post is about the blood test.

The numbers on the report

In the United States, uric acid is reported in mg/dL. Much of the world uses µmol/L. The MSD Manual SI converter gives the factor as 59.5:

µmol/L = mg/dL × 59.48

Guidelines often round these. The European targets below are written as 360 and 300 µmol/L. If any of your results are in µmol/L, convert them before you chart them, or the line will jump about sixtyfold at the switch. The lab unit converter has the factor for uric acid and other common tests.

Ranges differ by sex

Men run higher than women on average, so labs usually print separate ranges. In the U.S. national survey analyzed by Zhu, Pandya, and Choi, the average was 6.14 mg/dL in men and 4.87 mg/dL in women. That study defined hyperuricemia as above 7.0 mg/dL in men and above 5.7 mg/dL in women, and found it in about 21 percent of each.

The range printed on your report describes typical people. It is not a gout target. A man with gout and a uric acid of 6.9 can see no flag on the report and still be well above where treatment is aiming.

Targets in gout

For people with gout who take urate-lowering medication, the targets are lower than most lab ranges:

The ACR strongly recommends a “treat-to-target” approach: adjusting the dose based on repeated urate results until the level is below 6, and keeping it there. The 2016 EULAR recommendations use the same target, with a lower one for people with severe gout.

High uric acid without gout

A high result with no gout attacks and no tophi is called asymptomatic hyperuricemia. The ACR conditionally recommends against starting urate-lowering medication for it. In the trials it reviewed, gout developed in under 1 percent of people on treatment and 5 percent on placebo over three years, so 24 people would need to be treated for three years to prevent one case. For most people with a high uric acid and no symptoms, the result is something to watch, not to treat.

How often it is tested

Uric acid has no screening schedule. It is often on a metabolic panel, and it is ordered for a reason when gout or kidney stones come up. During treatment, it is checked often:

• Starting medication. The ACR recommends starting allopurinol at 100 mg a day or less, and lower with kidney disease, or febuxostat at 40 mg a day or less, and then raising the dose until the target is reached.
• Adjusting the dose. The guideline says titration should take weeks to months, not years, and that uric acid should be checked after each dose change. The ACR’s earlier 2012 guideline described raising the dose every 2 to 5 weeks.
• At target. The ACR strongly recommends continuing treatment to keep uric acid below 6, which means periodic checks for as long as you take it.

That produces a distinctive history: a cluster of results a few weeks apart, stepping down with each dose increase, then a flatter line with longer gaps.

Results drawn during a flare

A uric acid drawn during a gout attack can be misleading. In a study of 339 people with acute gout, 14 percent had a uric acid of 6 mg/dL or lower at the time of the attack, and 32 percent were at 8 or below. The authors’ conclusion was blunt: a normal level at the time does not rule out gout.

So a result drawn on the day of a flare is a poor baseline. If your history has one, mark it as a flare result and look to the draws before and after it for your usual level.

Starting medication can itself trigger flares at first. The ACR strongly recommends an anti-inflammatory medication, such as colchicine, for at least 3 to 6 months after starting. If an attack happens during that time, it does not mean the drug failed. Check the uric acid trend before deciding anything.

What counts as a real change

Unlike many tests, uric acid is fairly steady from week to week in healthy people. The European Biological Variation Study, which sampled 91 adults weekly for 10 weeks, found within-person variation of about 8 percent: 7.7 percent in men and 9.2 percent in women. By the usual rule of thumb (about 2.8 times that figure, before adding any lab measurement error), two results need to differ by roughly 23 percent before the change is likely to be real.

In practice:

• A 6.4 followed by 6.0 is within the noise. Even though the second one crosses the target line, nothing has necessarily changed.
• A 7.8 followed by 5.6 after a dose increase is a real move. That is a drop of more than a quarter, in the direction you expected.
• Several results below target in a row are what treat-to-target is after. One result just under 6 is a start.

Because the test is fairly steady, an unexpected jump usually has a cause worth finding: a missed week of medication, a new diuretic, an illness, or a change in kidney function.

Things that move uric acid

• Alcohol, especially beer. In a national survey analysis, each daily serving of beer was linked to uric acid about 0.46 mg/dL higher, and each serving of liquor to about 0.29 mg/dL higher. Moderate wine drinking was not linked to a higher level. The ACR conditionally recommends limiting alcohol for people with gout.
• Fructose and purines. The ACR guideline notes that 1 gram of fructose per kilogram of body weight raises uric acid by 1 to 2 mg/dL within 2 hours, and it conditionally recommends limiting high-fructose corn syrup and purine intake. MedlinePlus lists red meat, organ meats, and some seafood, such as shellfish and anchovies, as purine-rich.
• Weight. The ACR conditionally recommends weight loss for people with gout who are overweight.
• Fasting and very low-carbohydrate diets. The NKF report notes that ketones and lactate in the blood can raise uric acid by competing with it in the kidney.
• Kidney function. As kidney function falls, less urate is cleared. The NKF report points out that even small changes in kidney function move uric acid, which is one reason studies linking the two are hard to interpret. Lowering urate does not seem to protect the kidneys, though. In the CKD-FIX trial, allopurinol did not slow the decline in eGFR compared with placebo. How to track your eGFR over time covers the kidney side.
• Diuretics. The ACR conditionally recommends switching from hydrochlorothiazide to another blood pressure drug when feasible for people with gout, because of its effect on uric acid.
• Low-dose aspirin. In a study of older adults, 75 mg a day caused a small but significant rise in uric acid, which shrank at higher doses. The ACR recommends against stopping low-dose aspirin for this reason if you take it for your heart.
• Losartan. It lowers uric acid modestly. The ACR conditionally recommends choosing it over other blood pressure drugs for people with gout when feasible.
• Fenofibrate. It also lowers uric acid, but the ACR conditionally recommends against switching to it for that purpose, because of its other risks.
• SGLT2 inhibitors. These diabetes and heart failure drugs lower uric acid. A meta-analysis of 55 trials found an average drop of about 34 µmol/L, or roughly 0.6 mg/dL, compared with placebo.
• Niacin can affect results, according to MedlinePlus.
• Urate-lowering drugs. Allopurinol and febuxostat lower uric acid, which is the point. A stretch of missed doses can show up on the next result.
• Cancer treatment. Rapid breakdown of tumor cells can raise uric acid sharply, which is why it is monitored during some chemotherapy. This is rare outside that setting.

Did the medication actually do anything? covers reading a before-and-after fairly when one of these starts or stops.

What to record with each result

For each uric acid, keep:

Uric acid appears under a few names: Uric Acid, Urate, and “Uric Acid, Serum”. Pick one and use it everywhere, or your history will split into short, separate lines.

Charting it

A few choices make a uric acid chart honest:

• Draw your target, not just the lab range. If you have gout and are on treatment, a line at 6 (or 5) tells you more than a lab range with a higher upper limit.
• Mark every dose change of allopurinol or febuxostat, and read the next result as the effect of that dose.
• Mark flares separately from routine draws, and do not treat a flare-day value as your baseline.
• Put eGFR or creatinine on the same timeline. A rise in uric acid that lines up with a fall in kidney function has a likely explanation.
• Space points by date. Monthly checks during titration and yearly checks later should not look evenly spaced.

How to track your lab results over time has the general method for any test.

Tracking uric acid in HealthViewer

HealthViewer is a lab results tracker that runs on your own computer. It imports uric acid from lab report PDFs, MyChart downloads, and direct connections to your health system. Results named Uric Acid, and uric acid sent by your health system under its standard code, file under one test. Results in µmol/L or mmol/L are converted so they share one chart with results in mg/dL, and the chart title shows the unit in use. A name like “Uric Acid, Serum” or “Urate” can arrive as a separate test. Combine them with Merge… in the Test Catalog to get one line.

In Trends, the Metabolic tag pulls together uric acid, A1c, glucose, magnesium, and phosphorus, and the Kidney tag has creatinine and eGFR. The overlay view puts uric acid and eGFR on one chart. Enter each allopurinol or febuxostat dose as its own period in Medications, and medication markers show every change on the uric acid chart. Set your target as a custom range in the Test Catalog, such as below 6 mg/dL, and the chart shades that band instead of the lab’s range.

Add a journal entry for each flare, with a tag such as “gout”, and turn on Show journal in Trends to see flares next to the results around them. The Medication Effect report gives a before-and-after table for a drug’s start date.

Everything stays in an encrypted file on your computer, with no account and no cloud service. Getting Started walks through the first import.

This post is general information, not medical advice. Talk to your clinician about your uric acid target and before starting or changing any treatment.