Background: The study of the involvement of fructose in the pathogenesis of cardiometabolic disease requires accurate and precise measurements of serum and urinary fructose. The aim of the present study was to develop and validate such a method by Ultra Performance Liquid Chromatography–tandem Mass Spectrometry (UPLC-MS/MS).

Methods: Fructose concentration in serum and 24-hour urine collection was quantified using a UPLC-MS/MS method. Serum fructose was determined in healthy individuals (n=3) after a 15-gram oral fructose load. Twenty-four hours urinary fructose concentrations were determined in individuals consuming low (median: 1.4 g/day [interquartile range: 0.9-2.0]; n=10), normal (median: 31 g/day [23-49]; n=15) and high (median: 70 g/day [55-84]; n=16) amounts of fructose.

Results: Quantitative analysis of fructose in serum and urine was successfully achieved with inter- and intra-assay variations of ~5%, linear calibration curves (r²>0.99) over the physiological range and recoveries in serum and urine of ~92%. Fasting serum fructose levels (5.7±0.6 µmol/L) increased 60 minutes after a 15-gram oral fructose load (to 150.3±41.7 µmol/L) and returned to normal after 180 minutes (8.4±0.6 µmol/L). Twenty-four hours urinary fructose concentration was significantly lower in low fructose consumers when compared to normal and high fructose consumers (median: 36.1 µmol/day [interquartile range: 26.4-64.2], 142.3 µmol/day [98.8-203.0], and 238.9 µmol/day [127.1-366.1], p = 0.004 and p < 0.001, respectively).

Conclusion: Fructose concentrations can be measured accurately and precisely with this newly developed UPLC-MS/MS method, which can be applied in clinical studies.