The balance between yin and yang (Physiological process)

                                                                                   Normal level

   +             －

The imbalance between yin and yang (Pathological changes)

Relative predomination of yin and yang (Excess of pathogenic factors leads to excess syndrome).

Relative predomination of yang (Excessive-heat syndrome marked by predomination of yang and non-deficiency of yin)

Predomination of yang impairs yin.

                                      Normal level

          +          －

                                     Normal level

   +         －

Clinical manifestation: fever accompanied by profuse sweating, thirst, reddish complexion, reddish tongue with yellowish coating, full and large or rapid pulse; or accompanied by dysphoria, insomnia, mania, dry feces, scanty brownish urine, etc.

Predomination of yang impairs yin. At the medium and advanced stages of disease, pathogenic yang gradually declines and the consumption of yin is more serious, leading to yin-deficiency syndromes.

Relative predomination of yin (Excessive-cold syndrome marked by predomination of yin, decline of body functions and retention of pathological substances in the course of disease)

Predomination of yin impairs yang.

                                      Normal level

        +            －

                                   Normal level

       +           －

Clinical manifestation: cold symptoms, such as chills, pale complexion, anhidrosis, preference to hot water, cold limbs, loose stool, clear urine, whitish tongue fur, deep and slow pulse, etc.

Predomination of yin impairs yang. At the medium and advanced stages of disease, pathogenic yin gradually declines and yang is more deficient, leading yang-deficiency syndromes.

Relative decline of yin and yang (Relative decline of yin and yang can lead to deficiency syndrome, that is, “loss of essence causes deficiency”.)

Relative decline of yang (Deficiency-cold syndrome)

Deficiency of yang affecting yin.

                                        Normal level

       +             －

                                  Normal level

       +            －

Clinical manifestation: aversion to cold, cold limbs, mental lassitude, poor appetite, loose stool, clear and profuse urine, and deep-slow-weak pulse, etc. Deficiency of yang can’t restrict yin, leading to interior exuberance of yin-cold or retention of water-dampness or interior blockage of blood stasis. Yang-deficiency syndrome mainly involves the spleen and the kidney.

Deficiency of yang affecting yin means that consumption of yang-qi involves yin-fluid and makes yin-fluid insufficient in production, leading to a morbid state marked mainly by deficiency of yang with the manifestation of deficiency of both yin and yang.

Relative decline of yin (Deficiency-heat syndrome)

Deficiency of yin affecting yang.

                                      Normal level  

          +           －

                                  Normal level

      +            －

Clinical manifestation: emaciation, low fever, feverish sensation in the five centers(palms, soles and chest), night sweating, dry mouth, dry feces, scanty urine, reddish tongue fur or no tongue fur, thin and rapid pulse, etc. Deficiency of yin can’t restrict yang and leads to endogenous heat and fire with the symptoms of irascibility and insomnia, etc. Yin-deficiency syndrome mainly involves the liver and the kidney.

The consumption of yin-fluid involves yang, and makes yang insufficient in production or exhausted, leading to deficiency of yin with the manifestation of deficiency of both yin and yang.