What's wrong with half moon marks?

Half moon mark refers to a white half-moon shape at the lower part of the nail, which accounts for about one-fifth of the nail. We normally call it a healthy circle, which represents the performance of full blood essence and exuberant qi and blood of the human body. Ordinary healthy people show it on the thumb, index finger, middle finger, ring finger, little finger, etc., especially the half moon mark of the thumb. However, when a person's half-moon mark decreases, accompanied by the pale and brittle claw armor, this time is to consider the blood deficiency in the body, insufficient blood, unable to nourish the body's viscera and meridians. If the half-moon mark is less accompanied by cold hands, it is considered that it is caused by yang deficiency, unable to warm the extremities. If the half-moon mark becomes blurred, reduced or even disappeared, it is necessary to consider the body's blood essence deficiency, or the function of the spleen and stomach declines, or it may be caused by lack of sleep.