The diagnosis of vitiligo involves a physician taking a medical history and performing a physical examination. Blood tests or other tests are not normally required. In the evaluation of a patient’s medical history, a physician will look for certain information, including:

• Whether there is a family history of vitiligo
  
  
• Any rash, sunburn or other trauma of the skin two to three months prior to depigmentation
  
  
• Any recent stress or physical illness
  
  
• Presence of gray hair before the age of 35
  
  
• Patient or family history of autoimmune diseases (e.g., thyroid disorder)
  
  
• Any increased sensitivity to the sun

Physical examination includes examination under visible and ultraviolet light. Examination under visible light generally reveals white skin macules (patches), but it may be difficult to distinguish between vitiligo and other causes for light patches of skin. Wood’s lamp examination uses ultraviolet A light to detect truly depigmented areas. The white skin of vitiligo has a characteristic yellow-green or blue fluorescence under this form of examination.