To verify a new diagnostic method in traditional Chinese medicine (TCM), we evaluated the function of meridians using thermal sensitivity measurement (TSM), and conducted a comparative study between nephropathy patients and healthy individuals. We also evaluated whether TSM is useful for diagnosing nephropathy. The subjects included nephropathy patients (n = 203) and healthy individuals (n = 826). Heat detection times were measured at the well points on both the left and right sides of the twelve meridians. Multivariate analysis was conducted, with the presence or absence of nephropathy as the objective variable and the heat detection times of each meridian as the explanatory variable. The meridians identified as important for diagnosing nephropathy included the pericardium meridian, the triple energizer (sanjiao) meridian, small intestine meridian, liver meridian, bladder meridian, and kidney meridian. A diagnostic method combining age and the heat detection times of these meridians achieved sensitivity and specificity of over 80%. This method intuitively and quantitatively reflects the sub-heat and sub-cold states of each meridian, and is expected to enrich the diagnostic methods in traditional Chinese and Oriental medicine.