Nails can be affected by a variety of disorders that can cause deformities (changes in nail shape) and dystrophies (changes in nail texture).
Causes of nail disorders:
Internal diseases (lung disease, diabetes, cancer, impaired kidney or liver function, etc)
Structural problems such as an ingrown toenail
Medications and Drugs
Autoimmune Disease (psoriasis, lichen planus, etc)
Your Dermatologist can usually diagnose the type of nail disorder by examination, however to confirm a diagnosis they may take a fungal scraping or biopsy and send the specimen to a lab to be tested.
There are many congenital birth anomalies that can present with nail deformities, including the following:
Anonychia – babies born without nails
Nail-patella syndrome – thumbnails are missing or are small with pitting and ridges
Darier disease – causes red and white streaks on the nails and V-shaped notches on the tips of the nails
Pachyonychia congenita – nail beds are thickened and discolored with curved deformities
There are many nail changes that can reveal an underlying systemic condition:
Onycholysis: distal separation of the nail plate from the underlying nail bed may be associated with thyroid disease, especially hyperthyroidism.
Clubbing: increased transverse and longitudinal nail curvature may be hereditary, idiopathic, or acquired in association with a variety of disorders, particularly neoplastic, pulmonary, cardiac, gastrointestinal, infectious, endocrine, vascular, and multisystem diseases.
Koilonychia: concave thin nails with everted edges shaped like a spoon may result from iron deficiency anemia, hemochromatosis, trauma, constant exposure of hands to petroleum-based solvents, or nail-patella syndrome.
Onychomadesis: proximal separation of the nail plate from the nail bed resulting in shedding of the nail is usually secondary trauma, but may also occur from poor nutritional status, febrile illness, or drug sensitivity.
Beau’s lines: transverse depressions in the nail plate that occur as a result of a temporary cessation in nail growth are often the result of trauma, poor nutritional status, febrile illness, and drug sensitivity.
Pitted nails: pinpoint (or larger) depressions in an otherwise normal nail are usually associated with psoriasis but has also been reported in patients with reactive arthritis (and other connective tissue disorders), sarcoidosis, pemphigus, alopecia areata, and incontinentia pigmenti.