LAUSR

Abstract Introduction Tongue diagnosis is a convenient and non-invasive method for examining the functional condition of the body. The presence of teeth marks (TMs) on the tongue surface indicates a swollen tongue and decreased resilience of the tongue surface. The aim of this study was to investigate whether teeth mark level (TML), a novel TM indicator, is useful for determining deficiency patterns (DPs) in patients with chronic fatigue (CF). Methods In total, 152 participants with CF were recruited. They were classified by two Korean medicine doctors (KMDs) into the following groups: qi deficiency (n = 45), blood deficiency (n = 37), yin deficiency (n = 36), and yang deficiency (n = 34). All the participants’ tongue images were obtained with a computerized tongue image analysis system after the diagnostic process. To objectively measure TMs, we calculated TMLs from the tongue images. Results Differences in the TMLs among the DPs were analyzed with multiple linear regression analysis. The TMLs of the clay-tongue models showed a close relationship with the number and depth of the TMs (r = 0.99 and 0.98, respectively). The TMLs showed different trends according to the DPs (P  Conclusions The close relationship between TML and the DPs suggests that TML has the potential to be used in clinics as a supplementary means to differentiate among syndromes in CF and to evaluate therapeutic effects and prognosis in CF. Trial registration: CRIS no. KCT0001199.