Gray nail is a slow-onset infectious skin disease caused by a pathogenic fungus that infects the nails of the hands and feet. Although it is not a major pain, it affects the aesthetics and, in severe cases, the mood and interpersonal relationships. Recently, there have been many patients visiting the clinic and consulting about nail disease. Here are some tips related to gray nails for your reference. The medical standard disease name for gray nails Nail fungus (tinea unguium): A disease caused solely by the invasion of the nail plate or the tissue under the nail by the fungus tinea dermatica. Nail fungus (onychomycosis): A disease caused by dermatophytes, yeasts, and molds that invade the nail plate or the tissues under the nail. Causes of gray nails The fungi that can cause gray nails are: Trichophyton rubrum, Trichophyton gummi, Trichophyton flocculentum epidermidis, Trichophyton hirsutum, Trichophyton purpureum, Trichophyton broken hair, Trichophyton roseus, Trichophyton homocentricum, Candida albicans, Trichophyton short broomei, and Candida smoothus. The incidence of gray nail 5.69% in the normal population; 50% in nail disease. The six clinical forms of gray nails 1, distal lateral subxiphoid type: lesions from the nail edge end and lateral starting nail plate cloudy, thick, brittle. It is often accompanied by tinea pedis. 2. White superficial type: The dermatophytes directly invade the nail plate without invading the nail bed, and the surface of the diseased nail shows white cloud-like patches of white spots. 3.Subproximal nail type: The pathogenic fungus invades the proximal nail plate from the nail plate near the nail fissure, and then extends from the proximal to the distal end to the whole nail. 4.Candida: Candida spp. invade the nail, manifesting as chronic nail infection, distal nail to whole nail infection, nail degeneration, puffing, brittle, hypertrophy, unevenness. 5, whole nail dystrophic: it is the above types of lesions further development, the nail plate all invasion, manifested as the whole nail loss of luster, metamorphosis, nail loss, nail bed thickening. 6. Intrinsic type: It is the invasion of the disease-causing fungus from the distal end of the nail plate into the interdigital nail plate with a normal nail plate surface. Why must there be fungal evidence for the diagnosis of gray nails? The diagnosis of gray nails cannot be made solely on the basis of the above-mentioned patterns seen by the naked eye, but must have fungal evidence. This is because there are many nail diseases similar to gray nails, such as nail disease from psoriasis, nail dystrophy, flat nail moss, congenital thick nail disease, congenital white nail disease, and nail diseases caused by eczema, scleroderma, Raynaud’s disease, and continuous acrodermatitis. The most commonly used method of mycological examination is the fungal direct microscopy method: scrape some diseased nail debris with a razor blade, add potassium hydroxide (KOH) dissolved and then directly observed under the microscope. Its sensitivity is 80%, specificity is 70%, and the positive rate is 88%. However, a fungal culture is required to clarify the type of fungal properties that cause the disease. What are the risk factors that cause gray nails? 1. Tinea capitis. Many gray nails are transmitted from tinea pedis to the nail, and some people believe that “if you have tinea pedis, you won’t have other diseases”, which is not scientific. 2.Sharing contaminated slippers. 3.Walking barefoot on the ground in public bathrooms and swimming pools. 4.Nail trauma. 5.Disorders of peripheral blood circulation in the fingers and toes. 6.Chronic diseases, low immune function. 7.Summer humid climate. 8.Hand and foot hyperhidrosis.