Insufficiency of the lung yin

Clinical manifestations : Unproductive cough, cough with a small amount of sticky sputum, or cough with blood tinged sputum ; dryness of the mouth and throat, afternoon fever, malar flush, night sweating, heat sensations in the palms and soles, a red tongue with a small amount of coating and a thready, rapid pulse.

Etiology and pathology : This syndrome is often due to a prolonged cough which consumes the lung yin ; to overstrain and stress ; or to invasion of exogenous pathogenic dryness which causes insufficiency of the lung yin and, further, the production of deficiency type heat in the interior. Consumption of yin deprives the lung of moisture and allows upward disturbance of the lung qi, the result being cough with a small amount of sputum, dryness of the mouth and throat. Injury of the lung vessels by cough produces blood tinged sputum. Deficiency of yin leads to hyperactivity of fire, resulting in afternoon fever, malar flush, night sweating and heat sensations in the palms and soles. A red tongue with a small amount of coating, and a thready rapid pulse are both signs of heat due to deficiency of yin.