Difficulty 24 states: When the Qi of the three Yin and three Yang meridians of the hands and feet is exhausted, what are the clinical manifestations? Can one determine the prognosis (auspicious or inauspicious) from them? The answer is: When the Qi of the Foot Shaoyin Meridian (Kidney Meridian of Foot-Shaoyin) is exhausted, the bones become withered. The Foot Shaoyin Meridian corresponds to winter; its Qi sinks and circulates internally to warm the bone marrow. Therefore, if the bone marrow is not warmed, the muscles will fail to adhere to the bones, and the flesh and bones will lose their intimate connection. Consequently, the muscles will become flaccid and retract. Due to this retraction, the teeth appear elongated and withered, and the hair loses its luster. This indicates that the Qi of the bones has perished first. The condition will worsen on Wu days and death will occur on Ji days.
Ding stated: The Foot Shaoyin Meridian is the Kidney Meridian, which belongs to Water and prospers in Winter. It nourishes the bone marrow internally and manifests its splendor externally in the hair. When its Qi is exhausted, the gum line recedes making the teeth appear long, the bones wither, and the hair loses its luster. Thus, the condition worsens on Wu days and death occurs on Ji days. This describes the physical signs of exhaustion of the Foot Shaoyin Meridian.
Yang stated: The Foot Shaoyin Meridian is the Kidney Meridian. The Kidney governs Winter, hence it is called the Winter Pulse. The Kidney governs the internal nourishment of the bone marrow, hence it is said to sink and circulate to warm the bone marrow.