The absence of a crescent moon on the fingernail is generally normal, but in a small number of patients the absence of a crescent moon on the fingernail may be abnormal, due to the presence of a disease that causes the disappearance of the crescent moon. In most patients, the absence of a crescent moon on the fingernail is normal. Fingernail crescent, also known as the nail half moon, is in the lower one-fifth of the nail, appeared in a white curved traces, it is not completely keratinized nails. In some patients, the nail bed is more backward, revealing the nail has been completely keratinized, you can not see the crescent moon; and the crescent moon is usually with the age of the gradual decrease or disappearance. Therefore, the absence of crescent on the nail is generally a normal phenomenon. However, a small number of patients with no crescent on the nail may belong to the disease situation. Due to skin diseases such as nail psoriasis, lichen planus or nail eczema, the boundary between the half-moon and the nail bed will become blurred, and the crescent may even disappear. In addition, systemic diseases such as renal failure and liver failure can result in the entire nail bed being white and the lunula structure not being visible. Usually, after treating the primary disease, the crescent will gradually return to normal. Therefore, no crescent on the fingernail is generally normal, if the crescent on the fingernail suddenly disappeared and accompanied by uncomfortable symptoms, you should consult a doctor in a timely manner to find out the cause, under the guidance of the doctor to standardize the treatment.