The invention provides a method of diagnosing
overactive bladder disorder (OAB), the method comprising: measuring the concentrations of one or more of
adenosine triphosphate (ATP),
acetylcholine (ACh),
nitric oxide (NO) and
interleukin 5 (IL-5) in a sample obtained from a subject; normalising the concentrations to the concentration of
creatinine (Cr) in the sample; range standardising the normalised concentrations and subject's age to the following values: Age to 120 years old; ATP / Cr to 0.000001; ACh / Cr to 0.1; NO to 20000; IL-5 / Cr to 100; wherein the likelihood of having OAB (pOAB)=1 / 1+e−x, where X=one or more of the following: (a) (−2.688±1.050)+5.472±2.098×subject's age+1.356±0.559×Gender (Female=1, Male=0)+(−7.998±40.273)×[IL-5 / Cr]; (b) (−2.141±0.966)+4.506±1.902×subject's age+1.034±0.519×Gender (Female=1, Male=0)+(−5294.063±9075.456)×[ACh / Cr]; (c) (−2.825±1.072)+5.964±2.167×subject's age+1.312±0.562×Gender (Female=1, Male=0)+17.790±58.762×[IL-5 / Cr]+(−9180.821±12700.057)×[ACh / Cr]; (d) (−2.993±1.197)+5.580±2.309×subject's age+1.724±0.719×Gender (Female=1, Male=0)+63.571±73.444×[IL-5 / Cr]+(−0908.523±13606.752)×[ACh / Cr]+(−566.991±636.589)×[ATP / Cr]; (e) (−3.090±1.200)+5.393±2.256×subject's age+1.797±0.717×Gender (Female=1, Male=0)+34.767±56.331×[IL-5 / Cr]+(−562.743±629.316)×[ATP / Cr]; or (f) (−2.650±1.067)+5.516±2.120×subject's age+1.389±0.583×Gender (Female=1, Male=0)+(−4.060±45.238)×[IL-5 / Cr]+(−1.456±6.833)×[NO / Cr]; and wherein a pOAB above a threshold indicates that the subject has a
high likelihood of having or developing OAB and a pOAB below a threshold indicates that the subject does not have OAB.