Our hypothesis was that OSA’s recurrent hemodynamic events on the kidney—resembling renal ischemia-reperfusion injury [23,24]—would result in elevated urinary NGAL levels before any detectable increase in serum creatinine, as is observed in both experimental [25,26] and clinical [27–29] models of kidney ischemia-reperfusion injury. This evidence concerns the gene LCN2 and obstructive sleep apnea syndrome.