Fragile, thin nails are seen in iron deficiency anemia, vitamin A overdose, vitamin deficiency states (vitamins A, C, and B6), chronic infections, arsenic poisoning, and many different genetic syndromes. “Brittle nails,” however, are more commonly caused by soaps, detergents, and frequent exposure to moisture (particularly to hot water).


Transverse grooves (Beau−Reil lines) indicate temporary cessation of matrix activity and are easiest to see in the thumbs and great toes. They can be caused by transient, serious illnesses such as acute infections and Stevens−Johnson syndrome, or by the use of cytostatic agents. The maximal variant of this condition, with permanent cessation of nail growth and loss of the nail, is called onychomadesis.


Longitudinal grooves are usually seen in advanced age as a physiological variant but may be due to ischemia or rheumatoid arthritis. Longitudinal grooves combined with fissure formation are seen in hypoparathyroidism, underlying neoplastic disease, or trauma.

Concavity or “spooning” of the nails (koilonychia) may be idiopathic, congenital, or acquired. It often accompanies iron deficiency anemia, hemochromatosis, and polycythemia vera, and is occasionally due to endocrine disease (thyroid dysfunction, diabetes mellitus).


Onycholysis (detachment of the nail from its bed) is seen in skin diseases (psoriasis, eczema, bullous diseases), as an adverse drug effect (cytostatic agents), as an effect of photosensitizing medications (photo-onycholysis after the use of tetracyclines, chlorpromazine, allopurinol, or PUVA therapy), in systemic disease (lupus erythematosus, thyroid dysfunction, iron deficiency anemia), as a hereditary condition, and in infectious diseases (fungal infection, syphilis, viral infection). It can also be induced by local factors (trauma, detergents, solvents).


Subungual splinter hemorrhages appear in many different types of disease (collagenoses, vasculitis, diabetes mellitus, hepatitis, HIV infection, sarcoidosis, amyloidosis, and mechanical trauma). They are by no means specific for endocarditis and may also be seen in uncomplicated mitral stenosis.


Crumbly nail dystrophy (subungual hyperkeratosis) is typically seen in fungal infections and psoriasis vulgaris. In addition to crumbly decomposition of the nails, psoriasis produces typical “oil droplets” (nail bed psoriasis) and pinhead-sized indentations, in combination with distal onycholysis. Pitted nails are highly characteristic, but not pathognomonic, of psoriasis vulgaris; similar changes are seen in eczema and severe cases of alopecia areata. Subungual hyperkeratosis can also have a mechanical cause, as it can be induced by continuous pressure on the nail (often seen in the fourth and fifth toes).

The transverse lines of Mees (white stripes) are usually the product of a febrile illness, intoxication (usually arsenic or thallium), or traumatic event.


Hourglass nails (“clubbing”) are broader than normal nails; drumstick nails are a more advanced form of the same phenomenon. Drumstick nails are occasionally seen as a hereditary phenomenon but are usually caused by one of the following conditions:

➤ lung diseases (bronchiectasis, empyema, emphysema, bronchial carcinoma, cystic fibrosis, mesothelioma, sarcoidosis with pulmonary fibrosis)

➤ cyanotic congenital heart defects

➤ malignant tumors (mainly intrathoracic tumors and metastases)

➤ less commonly (5% of cases), gastrointestinal disorders (Crohn disease, ulcerative colitis, primary biliary cirrhosis, polyposis, sprue)

➤ hematologic diseases causing hypoxia, and endocrine diseases (hyperthyroidism).

Drumstick fingers are frequently associated with a hypertrophic osteoarthropathy: for example, hypertrophic pulmonary osteoarthropathy (Bamberger−Marie syndrome) manifests itself with drumstick fingers (and toes) as well as periosteal neo-ossification of the long bones, arthralgias, and symptoms such as flushing and profuse sweating. This syndrome is practically pathognomonic for malignant tumors, particularly bronchial carcinoma and pleural mesothelioma, though bronchiectasis also rarely causes it.


Characteristic nail dystrophies appear in congenital disorders including epidermolysis bullosa, progeria, congenital dyskeratosis, congenital pachyonychia, and the nail−patella syndrome. The last-named condition is transmitted in an autosomal dominant mode and manifests itself with hypoplastic thumbnails, a typical, triangular lunula, the lack of one or both patellae, other skeletal deformities, and, in just over half of all patients, renal involvement (glomerulonephritis). Heterochromia of the iris is also present and serves as a helpful clue to the diagnosis.


Lichen ruber planus occasionally affects the nails in isolation. It can cause a very wide variety of nail changes, ranging from rough, sandpaperlike nails (trachyonychia) to fragile nails, subungual hyperkeratosis, pterygiumlike changes, and complete nail loss, with atrophy and scarring.