Examining the Fingernails When Evaluating Presenting Symptoms in Elderly Patients

Introduction

Human fingernails, located on the dorsal aspect of the terminal 40% of the distal phalanx of each finger, are complex structures involving 3 different layers:

• The nail plate (the nail). This is the keratinized structure, which grows throughout life;
  
  
• The nail bed (ventral matrix, sterile matrix). This is the vascular bed that is responsible for nail growth and support. It lies protected between the lunula (the "half moon" seen through the nail) and the hyponychium (the posterior part of the nail bed epithelium); and
  
  
• The eponychium (cuticle). The epidermal layer between the proximal nail fold and the dorsal aspect of the nail plate.

The primary purpose of the nail is protection. Abnormalities of the nail are often caused by skin disease and infection (most often fungal) but may also indicate more general medical conditions. This discussion does not address localized trauma or nail infections but offers examples of nail abnormalities that may occur with systemic disease.

Check to see whether the nails are normal by looking at the following (Figure 1):

• Softness and flexibility of free edge;
  
  
• Shape and color;
  
  
• Quality of paronychial tissue; and
  
  
• Growth rate (about 6 months from cuticle to free edge). Time of events can be estimated from location.

Figure 1. The normal nail.

Examining the Nails

Elderly people carry the last 6 months of their medical record on the approximately 10 square centimeters of keratin comprising the fingernails. Examining the fingernails can help the clinician detect a number of general and specific factors, including the following:

• Overall vitality;
  
  
• Inner emotional state;
  
  
• Cerebral dominance;
  
  
• Occupations and hobbies;
  
  
• Medical history;
  
  
• Nutritional status;
  
  
• Cardiovascular function;
  
  
• Rheumatic conditions; and
  
  
• Dermatologic problems.

The patient's manicure can reveal state of health, nutritional status, past events, personality, occupation, and one's inner state. Systemic illness should show the nail changes in each of the nails on one hand. The thumb may reveal more extensive changes given its increased size.

It is useful to follow the following sequence when examining the nails:

• Check the nail shape;
  
  
• Examine the nail color;
  
  
• Survey processes around the nails;
  
  
• Compare hands; and
  
  
• Note skin conditions.

It is critical to examine the nails in adequate light. Gently rotate the nail in the light so that the reflection highlights all aspects of the nail. Notice the lunula, the pale crescent moonlike coloration at the base of the nail. Leukonychia stria and a pointed tent-like lunula suggest an excessive manicure and pushing on the cuticle. Paronychias suggest stress and poor attention to hygiene. This can reflect depression, dementia, or psychiatric illness.

Nail Growth

Nail growth is continuous. It takes about 6 months for a fingernail in an elderly person to completely grow out. Cold temperature can slow growth rates but not to any clinically significant degree (pun intended). The middle finger nail grows the fastest, followed by the forefinger and ring finger. Aging slows the growth rate from approximately 3 months in childhood to 6 months in 70-year-olds. Nails in elderly people are also thicker than in younger people. Thin nails in a postmenopausal woman raise the possibility of metabolic bone disease. The nails of the dominant hand grow slightly more quickly than the nondominant nails, probably because minor trauma accelerates nail growth. Conversely, immobility slows the growth rate of fingernails. Understanding the growth rate is important because the time interval from a critical event can be estimated from the location of a nail lesion. For example, a white line appearing transversely halfway up the nail suggests an acute illness 3 months earlier. Regular observation will demonstrate its progression to the end of the nail edge.

Nail Polish

Distance from base and line of polish gives approximate date of application (nails grow 0.1 mm/day). Picking at polish reflects nervousness and agitation. Toenail polish suggests unusual flexibility or a friendly helper.