ABSTRACT
Objective To investigate clinical characteristics and renal uric acid excretion in early-onset gout patients.Methods Consecutive inpatients with primary gout were recruited between 2013 and 2017.The patients with gout onset younger than 30 were defined as early-onset group while the others were enrolled as control group.Clinical characteristics and uric acid (UA) indicators were compared between two groups.Results Among 202 recruited patients,the early-onset group included 36 patients (17.8％).Compared with control group,the early-onset group presented more patients with obesity [13 patients (36.1％) vs.22 patients (13.3％),P＜0.05],significantly higher serum UA level [(634± 124)μmol/L vs.(527± 169).μmol/L] and glomerular load of UA[(7.2±2.8)mg· min-1 · 1.73m-2 vs.(4.4±2.2)mg· min-1 · 1.73m-2] and estimated glomerular filtration rate (GFR) [(83±21)ml· min-1 · 1.73m-2 vs.(67±21)ml· min-1 · 1.73m-2] (all P＜ 0.05),lower fractional excretion of UA [4.4％ (3.4％,6.1％) vs.7.2％ (5.2％,9.6％),P＜0.05],whereas 24h urinary UA excretion was comparable [(2 788±882)l,μmol/1.73m2 vs.(2 645±1 140)μmol/1.73m2,P=0.274].Subgroup analysis of patients without chronic kidney disease showed significantly lower fractional excretion of UA in the early-onset group [4.5％(3.3％,6.1％) vs.6.7％ (5.1％,8.7％),P＜0.05].Logistic regression analysis showed that obesity (OR=3.25) and fractional excretion of UA less than 7％ (OR=9.01,all P＜0.05) were risk factors of gout early onset.Conclusion The gout patients with early-onset younger than 30 present high serum and glomerular load of uric acid which might be due to obesity and relative under-excretion of renal uric acid.