1) Observing general appearances:

In traditional Chinese medicine, this is known as observing "Shen." Shen is the combined appearance of color and luster, but it is difficult to describe in ordinary terms, as it is a mixture of obscure color and blurred luster.

In modem physics, a weak visible light with a wave length of 3800-4200 angstrom (equal to the wave length of blue light) can be irradiated from the body's surface. The brightness of this light is related to the age, sex, physique, and physiological condition of the individual. This is a specific phenomenon showing the body's functional condition. This weak visible light irradiated from the body is similar to Shen described in traditional Chinese medicine, and it may be the scientific explanation for Shen.

In normal people, the hand and foot are bright and moist. The bightness of the skin should be gentle and viable to indicate the richness of essence and blood, and the fullness of spirit and energy described as Deshen (obtaining Shen) in traditional Chinese medicine.

If the hand and foot skin is dull, dry or haggard due to a reduction of luster and moisture, it is called "Shishen" (loss of Shen) in traditional Chinese medicine. This indicates the worsening of diseases, with a poor prognosis and difficult to cure.

If the hand and foot are dark, lusterless, and appear covered with a layer like dark frost, this indicates a reduction of immunity and a high susceptibility to viral influenza, high fever, nephritis, leukemia, tumor or rheumatic fever.

If the dull appearance and reduction of luster occurs in only a localized area of the hand and foot, this indicates the dysfunction of the organ related to this area, producing a serious disease in that organ and a poor prognosis.

The luster of the hand and foot may change with temperature, climate, or emotional and physiological conditions. However, these changes are usually only present in small areas and are of short duration. Therefore, it is important to determine changed general appearances of the hand and foot over a long period of time for correct clinical diagnosis.

In addition, a change in the luster of the hand and foot can also show the development of a disease. As the hand and foot gradually turn brighter and more lusterous and moist, the disease is subsiding to a certain extent and the health of the patient is gradually improved; but as the hand and foot turn gradually darker and less lusterous and dry, the disease is apparently gaining by degrees. This should draw the attention of the practitioner for timely and adequate treatment.