Background Gout is a metabolic disorder of purine metabolism with primary manifestations of acute and chronic arthritis and tophus formation. Asymptomatic gout is defined as tophus formation without any clinical symptoms of arthritis. Detection of asymptomatic gout may be important, as it can cause bone erosions and joint destruction. Reduced kidney function is an important risk factor for gout1. The prevalence of hyperuricemia and gout increases with decreasing estimated glomerular filtration rate (eGFR) independent of other risk factors for gout1. Dual Energy CT (DECT) and ultrasound (US) are novel radiological techniques to detect monosodium urate (MSU) crystals.
Objectives The aim of this study was to assess the prevalence of asymptomatic gout in patients with chronic kidney disease (CKD) stages 4 or 5, this is an eGFR <30mL/min/1.73m2.
Methods Patients with CKD stages 4 or 5 were recruited from a nephrology outpatient clinic in a university hospital. Exclusion criteria were a history of arthritis or gout, the use of urate lowering drugs and the use of more than 7.5 mg prednisone/day. The joints of the feet, ankles and knees were examined with US and DECT. The OMERACT criteria for gout lesions on US were used: tophi, MSU deposits and double contour sign2. A DECT was scored positive if at least one tophus was present3.
Results Twenty-five patients were included. Patients were recruited from a population of 387 patients with CKD stages 4 or 5, 208 were excluded because they did not meet the in-/exclusion criteria, 58 were not treated at the outpatient clinic anymore at time of inclusion and the rest declined participation. The mean (SD) age of the participants was 65 (12), 18 were man and the mean (SD) duration of CKD was 5.3 (3.8) years.
Twelve out of 25 patients (48%) had any sign of gout on DECT or US, nine patients (36%) had MSU depositions, four (16%) had a tophus, seven (28%) had a double contour sign and three patients (13%) had a positive DECT. Patients with MSU depositions were older (73 vs. 60 years, p=0.007). Gout signs were far more common in the high uric acid group, this is an uric acid of 0.42 or higher (table 1), although this did not reached a statistical significance.
Conclusions Our study shows a high prevalence of gout in patients with CKD. To our knowledge this is the first study that assessed the prevalence of asymptomatic gout in patients with CKD stages 4 or 5. Radiological signs of gout were more frequently found in patients with higher uric acid. The relevance of these findings needs further research.
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Disclosure of Interest None declared