DE-CT finds gout missed by traditional tests

The incidence of gout is on the rise in the western world, and this very painful and most common form of inflammatory arthritis is turning out to be more complicated than had been thought. The standard way to check for gout is by drawing fluid or tissue from an affected joint and looking for uric acid crystals, That usually works, but not always: In a new Mayo Clinic study (Bongartz T et al Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study Ann Rheum Dis. 2014. doi: 10.1136) it was found that dual-energy CT scans found gout in one-third of patients whose aspirates tested negative for the disease.

The study tested the usefulness of DE CT scans in finding uric acid crystals around joints across a spectrum of gout and found that CT scans worked particularly well in detecting gout in patients who had experienced several gout-like flares but whose previous needle aspirates came back negative. After CT scans found what appeared to be uric acid crystals, ultrasound-guided aspirates were taken in those areas and tested for urate crystals. “These were in part patients that had been falsely diagnosed with diseases like rheumatoid arthritis or labeled with a different type of inflammatory arthritis, resulting in a completely different and often not effective treatment approach,” says first author Tim Bongartz, M.D., “And there were patients who remained undiagnosed for several years with, for example, chronic elbow symptoms or Achilles tendon systems, where the CT scan then helped us to pick up uric acid deposits.” Gout is often thought of as a man’s disease and associated with sudden sharp, burning pain in the big toe. It’s true that until middle age, more men than women get gout, but after the menopause, women catch up in the statistics. And gout can hit more than the big toe: Other joints including parts of the feet, ankles, knees, fingers, wrists and elbows can also be affected.

An accurate and early gout diagnosis is crucial because gout patients are treated with different medication than people with other forms of inflammatory arthritis.