However, there are multiple underlying conditions that can also cause nail pits. One of the most common medical condition which causes nail pitting is psoriasis. Psoriasis is an inflammatory condition characterized by scaly skin lesions and arthritis. If you have these symptoms, then it is likely that the nail pitting is caused by the psoriasis. Sometimes the first symptoms of the psoriasis can be the nail pitting. Pitting of the nails can also be associated with alopecia areata, a genetic cause of hair loss, or eczema as well as a few other inflammatory conditions of the skin.
As always the diagnosis of your particular concerns will require a physical examination by your personal physician. A visit to your primary care doctor or your dermatologist would be a good step towards understanding your specific condition.