Physical exercise, fasting glucose, and renal hyperfiltration in the general population: the Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6).
OBJECTIVE
Abnormally elevated GFR, or hyperfiltration, is a proposed mechanism for kidney injury in diabetes, prediabetes, and obesity. This study investigated whether lack of physical exercise is associated with hyperfiltration and whether exercise modifies the positive association between fasting glucose and measured GFR.


METHODS
The Renal Iohexol Clearance Survey in Tromsø 6 measured GFR as single-sample plasma iohexol clearance in 1506 members of the general population (age 50-62 years) without diabetes, cardiovascular disease, or kidney disease. Leisure-time physical exercise was assessed by a self-administered questionnaire. Hyperfiltration was defined as GFR above the 90th percentile after adjustment for sex, age, weight, height, and use of renin-angiotensin system inhibitors.


RESULTS
High-intensity exercise was associated with lower adjusted odds of hyperfiltration in men (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.28-0.80) but not in women (OR, 1.02; 95% CI, 0.60-1.72). In both sexes, high-intensity exercise modified the association between fasting glucose and GFR. A fasting glucose level 1 mmol/L higher was associated with a GFR that was 7.3 (95% CI, 4.0-10.6) and 6.2 (95% CI, 3.4-9.0) ml/min per 1.73 m(2) higher in men and women who never exercised or exercised with low intensity. There was no association between fasting glucose and GFR in men and women who exercised with high intensity (interaction, P<0.001).


CONCLUSIONS
High-intensity exercise was associated with lower odds of hyperfiltration in men and modified the association between glucose and GFR of both sexes in a population without diabetes.
Section of Nephrology, University Hospital of North Norway, Tromsø, Norway. melsom@unn.no
Toralf
T
Melsom
Ulla Dorte
UD
Mathisen
Britt-Ann Winther
BA
Eilertsen
Ole C
OC
Ingebretsen
Trond
T
Jenssen
Inger
I
Njølstad
Marit D
MD
Solbu
Ingrid
I
Toft
Bjørn O
BO
Eriksen
D001786:Blood Glucose / Q000032:analysis*; D015444:Exercise; D005215:Fasting / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007472:Iohexol / Q000493:pharmacokinetics*; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged
D001786:Blood Glucose; D007472:Iohexol