Nerve growth factor levels in urine could prove a useful biomarker for interstitial cystitis/painful bladder syndrome and neurogenic overactive bladder.
A study from the University of Pittsburgh School of Medicine in collaboration with the William Beaumont Hospital in Royal Oak, MI, presented at the AUA annual meeting in Chicago looked at NGF levels in the urine of 72 patients with various urologic conditions: neurogenic OAB (13 patients), idiopathic OAB (17), IC/PBS (eight), prostate cancer (seven), history of prostate cancer status post-robotic prostatectomy (six), active bladder cancer (four), and nephrolithiasis (four).
NGF levels were measured by the enzyme-linked immunosorbent assay (ELISA) Emax ImmunoAssay System (Promega, Madison, WI) and normalized to the patient's urine creatinine (Cr) level. Mean levels of NGF/Cr in IC/PBS (31.24 pg/mg) and neurogenic OAB patients (23.02 pg/mg) were significantly higher than in controls (0.0 pg/mg; p=.004 and p=.006, respectively). NGF/Cr mean levels in patients with nephrolithiasis (19.46 pg/mg) approached significance compared with controls (0.0 pg/mg; p=.06).
"NGF, a signaling protein produced by bladder smooth muscle and urothelium, affects bladder afferent fibers," said first author Bruce L. Jacobs, MD, a urology resident at the University of Pittsburgh working with Pradeep Tyagi, PhD, of William Beaumont Hospital, and colleagues. Thus, it may be no surprise that the conditions with elevated levels are those in which urinary tract sensitivity or pain are prominent.
It's not yet clear how NGF measurements might be used.
"Potentially, clinicians could follow treatment response," Dr. Jacobs told Urology Times. "Urine NGF levels may be a biomarker to help better guide us in the evaluation and treatment of lower urinary tract symptoms."