Background: Strenuous exercise may trigger acute complications, such as exertional rhabdomyolysis and gastrointestinal complaint. As less is known about the potential renal impairment after long distance running, we assessed creatinine and neutrophil gelatinase associated lipocalin (NGAL) in serum (sNGAL) and urine (uNGAL) before and after an ultramarathon.
Methods: The study population consisted of 16 trained male athletes who ran a 60 km ultramarathon. Blood and spot urine samples were collected 20 min before and immediately after the run. Creatinine was assessed by Jaffe assay on Beckman Coulter AU5800 and renal function was expressed as estimated glomerular filtration rate (eGFR) by MDRD formula. NGAL was measured by fully-automated immunoassay NGAL Test™ on AU 5800.
Results: Serum and urinary creatinine increased significantly by 38% and 78%, respectively. The eGFR contextually decreased by 31%. sNGAL, uNGAL and uNGAL/creatinine ratio increased by 1.6-fold, 7.7-fold and 2.9-fold. In six of 16 athletes (38%), the acute post-exercise increase of serum creatinine met the criteria of acute kidney injury. No significant relationship was found between pre-exercise, post-exercise values and post-exercise variation of sNGAL, uNGAL and uNGAL/creatinine ratio. A significant correlation was found between pre- and post-exercise changes of serum creatinine and sNGAL, but not with either uNGAL or uNGAL/creatinine ratio.
Conclusions: The acute variations of serum creatinine and uNGAL attest that renal impairment is likely to develop after long distance running. The uNGAL seems more independent from creatinine variation and extra-renal sources, and thereby more reliable for monitoring the renal involvement in these types of kidney impairment.