Observing the Nail Shape and Surface
Clubbing involves a softening of the nail bed with the loss of normal Lovibond angle between the nail bed and the fold, an increase in the nail fold convexity, and a thickening of the end of the finger so it resembles a drumstick.
To determine whether nails are clubbed, have the patient place both forefinger nails together and look between them. If you can see a small diamond space between them (Schamroth's window) then the nails are not clubbed (Schamroth's sign) (Figure 2).
Figure 2. Schamroth's sign.
Causes of clubbing (not exhaustive) include the following (Figure 3):
Pulmonary and cardiovascular causes (80%)
Lung cancer, pulmonic abscess, interstitial pulmonary fibrosis, sarcoidosis, beryllium poisoning, pulmonary arteriovenous fistula, subacute bacterial endocarditis, infected arterial grafts, aortic aneurysm
Gastrointestinal causes (about 5%)
Inflammatory bowel disease, sprue, neoplasms (esophagus, liver, bowel)
Hyperthyroidism (about 1%)
Note: Chronic obstructive pulmonary disease does not cause clubbing.
Figure 3. Example of clubbed fingernails.
Koilonychia are spoon-shaped concave nails (Figures 4A, 4B). This occurs normally in children and usually resolves with aging. To determine whether a nail is spooned, perform the water drop test. Place a drop of water on the nail. If the drop does not slide off, then the nail is flattened from early spooning. An experienced clinician can look at the nail and perform a "mental" water drop test. Causes include the following:
Protein deficiency, especially in sulfur-containing amino acids (cysteine or methionine);
Exposure to petroleum-based solvents;
Figure 4A. Spooned nail.
Figure 4B. Spooned nail.
In 1846, Joseph HonorÃ© Simon Beau described transverse lines in the substance of the nail as signs of previous acute illness. The lines look as if a little furrow had been plowed across the nail. Illnesses producing Beau's lines include the following:
Intermittent doses of immunosuppressive therapy or chemotherapy can also produce Beau's lines. Severe zinc deficiency has also been proposed as a cause of Beau's lines.
By noting its location on the nail, the approximate date of the illness associated with it can be determined (Figures 5A, 5B). Moreover, the depth of the line provides a clue to the severity of the illness.
Figure 5A. The location of Beau's lines half way up the nail suggests illness 3 months ago.
Figure 5B. Two Beau's lines suggest illnesses about 2 months apart.
Thin Brittle Nails
Thin, brittle nails can indicate the following (Figure 6):
Metabolic bone disease (nail thinness is correlated with osteopenia);
Systemic amyloidosis (indicated by yellow waxy flaking); and
Figure 6. Note the thin nails in this woman with severe osteopenia.
Onychorrhexis is the presence of longitudinal striations or ridges (Figure 7). It can simply be a sign of advanced age but it can also occur with the following:
Lichen planus; and
Darier's disease (striations are red/white).
Central ridges can be caused by:
Folic acid deficiency; and
Figure 7. Example of a central nail ridge.
Central Nail Canal (Median Nail Dystrophy)
When a central nail canal is present, the cuticle is usually normal (Figure 8A). Central nail canal is associated with:
Severe arterial disease ("Heller's fir tree deformity" -- a central canal with a fir tree appearance -- may occur with peripheral artery disease (Figure 8B);
Severe malnutrition; and
Figure 8A. Example of central nail canal.
Figure 8B. Central nail canal with Heller's fir tree deformity.
Nail pitting -- small punctate depressions -- are caused by nail matrix inflammation, which can be the result of:
Psoriasis (random appearance of pits) (Figure 9);
Alopecia areata (geometric rippled grid) (Figure 10);
Figure 9. Indication of psoriasis.
Figure 10. Indication of alopecia areata.
With nail beading, the beads seem to drip down the nail like wax (Figure 11). It is associated with endocrine conditions, including the following:
Addison's disease; and
Vitamin B deficiency.
Figure 11. Nail beading.
Rough Nail Surface
When nails look sandpapered and dull, consider (Figure 12):
Chemical exposure; and
Figure 12. Example of a rough nail surface.
Slow nail growth produces thickness (Figure 13). In such cases, the following should be considered:
Peripheral vascular disease;
Yellow nail syndrome; and
Figure 13. Example of a nail thickening.
Onycholysis is distal separation of the nail plate from the underlying nail bed (Figure 14). It is associated with the following:
Toxic exposures (solvents);
Blistering from autoimmune disease; and
Porphyria cutanea tarda (onycholysis and skin blistering from sun exposure).
Figure 14. Traumatic onycholysis (involving only 1 nail).
Severe Nail Curvature (Beaked Nails)
Curved or beaked nails are caused by resorption of distal digit (Figure 15). Consider the following:
Figure 15. Example of severe nail curvature.
Complete Nail Destruction
Complete local nail destruction can be caused by local mechanisms, including trauma and paronychia. Generalized conditions that might cause complete nail destruction include the following:
Bullous diseases; and
Medscape Family Medicine © 2009
Cite this: Mark E. Williams. Examining the Fingernails When Evaluating Presenting Symptoms in Elderly Patients - Medscape - Nov 23, 2009.