The fructose tolerance test in patients with chronic kidney disease and metabolic syndrome in comparison to healthy controls.
BACKGROUND
Fructose acutely raises serum uric acid in normal subjects, but the effect in subjects with metabolic syndrome or subjects with chronic kidney disease is unknown. The aim of the study was to evaluate changes in serum uric acid during the fructose tolerance test in patients with chronic kidney disease, metabolic syndrome with comparison to healthy controls.


METHODS
Studies were performed in 36 subjects with obesity (body mass index >30) and metabolic syndrome, 14 patients with stage 3 chronic kidney disease, and 25 healthy volunteers. The fructose tolerance test was performed in each patient. The change in serum uric acid during the fructose challenge was correlated with baseline ambulatory blood pressure, serum uric acid, metabolic, and inflammatory markers, and target organ injury including carotid intima media thickness and renal resistive index (determined by Doppler).


RESULTS
Absolute serum uric acid values were highest in the chronic kidney disease group, followed by the metabolic syndrome and then healthy controls. Similar increases in serum uric acid in response to the fructose tolerance test was observed in all three groups, but the greatest percent rise was observed in healthy controls compared to the other two groups. No significant association was shown between the relative rise in uric acid and clinical or inflammatory parameters associated with kidney disease (albuminuria, eGFR) or metabolic syndrome.


CONCLUSIONS
Subjects with chronic kidney disease and metabolic syndrome have higher absolute uric acid values following a fructose tolerance test, but show a relatively smaller percent increase in serum uric acid. Changes in serum uric acid during the fructose tolerance test did not correlate with changes in metabolic parameters, inflammatory mediators or with target organ injury. These studies suggest that acute changes in serum uric acid in response to fructose do not predict the metabolic phenotype or presence of inflammatory mediators in subjects with obesity, metabolic syndrome or chronic kidney disease.


BACKGROUND
The study was registered in ClinicalTrials.gov. Identifier : NCT01332526. www.register.clinicaltrials.gov/01332526.
Department of Nephrology, Hypertension and Internal Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. rafdon@o2.pl.
Rafał
R
Donderski
Department of Nephrology, Hypertension and Internal Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. ilonamis@wp.pl.
Ilona
I
Miśkowiec-Wiśniewska
Department of Nephrology, Hypertension and Internal Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. markkret@neostrada.pl.
Marek
M
Kretowicz
Department of Nephrology, Hypertension and Internal Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. magdalena.grajewska@wp.pl.
Magdalena
M
Grajewska
Department of Nephrology, Hypertension and Internal Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. synowie2@o2.pl.
Jacek
J
Manitius
Department of Diabetology and Endocrinology, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. amikam@wp.pl.
Anna
A
Kamińska
Department of Diabetology and Endocrinology, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. junik@cm.umk.pl.
Roman
R
Junik
Department of Laboratory Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. asiapollak@wp.pl.
Joanna
J
Siódmiak
Department of Laboratory Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. diag.ka@wp.pl.
Anna
A
Stefańska
Department of Laboratory Medicine, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. odes@cm.umk.pl.
Grażyna
G
Odrowąż-Sypniewska
Institute of Public Nursing, Collegium Medicum, Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland. agnieszkapluta@poczta.onet.pl.
Agnieszka
A
Pluta
Division of Renal Diseases and Hypertension, University of Colorado Denver, Denver, CO, USA. Miguel.lanaspagarcia@ucdenver.edu.
Miguel
M
Lanaspa
Division of Renal Diseases and Hypertension, University of Colorado Denver, Denver, CO, USA. Richard.Johnson@ucdenver.edu.
Richard J
RJ
Johnson
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D018450:Disease Progression; D005260:Female; D005632:Fructose / Q000008:administration & dosage* / Q000097:blood; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000175:diagnosis*; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000175:diagnosis*; D012016:Reference Values; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000175:diagnosis*; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014527:Uric Acid / Q000097:blood*
D014527:Uric Acid; D005632:Fructose