A 4-year-old female came to clinic for her health maintenance examination. Her mother noted that she bit her fingernails. During the conversation, the mother asked how fast fingernails grow. The intern physician said he didn’t know but would ask. The attending physician said that he wasn’t sure but that it was a few millimeters per month generally, and that illness and other stresses could decrease the rate and pregnancy could increase the rate. The diagnosis of onchophagia was made. The mother was given this answer along with some ideas on how to try to decrease the nail biting.
Onchophagia or nail biting is a common disorder in children and adults. It is often due to habit but can become so prevalent that it is compulsive in some individuals. Understanding the situations when the behavior is more common (i.e. stressful situations, when bored, etc.) and finding ways to decrease the triggering situation is helpful. Additionally, finding ways to compete with the behavior is also helpful (i.e. holding on to clothing, sitting on the hands). Another alternative is to use deterrents such as nail polish that has a bad taste or using gloves to cover the hands.
Habit reversal training can also be helpful to decrease the behavior, and more information can be found here.
Fingernail growth is important as nails have been used for biomarking in epidemiological studies for toxins, drugs and nutrients over the past 20-30 years. Data on growth is unfortunately limited, and many studies are from more than 30 years ago.
In 2009, one study of young adults found that fingernail growth was faster than of toenails with great toes and thumbs having the highest rates on each extremity. Hand or foot dominance was not significant. Onchophagia was associated with faster nail growth but was not statistically significant. The average fingernail growth rate was 3.47 mm/month and toenail growth was 1.62 mm/month.
In a 1959 study, fingernail growth in adults was found to be 1.9-4.4 mm/month, with normal infants averaging 3.36 mm/month and premature infants (weight 1150-1900g) having a rate of 2.55 mm/month. The researchers also demonstrated growth arrest in a variety of acute and chronic diseases including measles and nutritional deficiencies. Interestingly, they also documented post-mortem nail growth in 3 adults followed for 8-10 days after death. They found a slightly decreased but normal fingernail growth rate for the first 2-3 days after death, and then a slower rate during the rest of the study period. The growth had not stopped at the time of discontinuation of the observations.
Questions for Further Discussion
1. How fast does hair grow?
2. At what age can you tell the permanent color of eyes?
3. Nails can be tested for what substances?
- Disease: Nail Diseases
- Symptom/Presentation: Behavior Problems
- Specialty: Dermatology | General Pediatrics
- Age: Preschooler
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Nail Diseases.
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
Sibinga MS. Observations on growth of fingernails in health and disease. Pediatrics. 1959 Aug;24(2):225-33.
Yaemsiri S, Hou N, Slining MM, He K. Growth rate of human fingernails and toenails in healthy American young adults. J Eur Acad Dermatol Venereol. 2010 Apr;24(4):420-3.
ACGME Competencies Highlighted by Case
1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
2. Essential and accurate information about the patients’ is gathered.
3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
4. Patient management plans are developed and carried out.
5. Patients and their families are counseled and educated.
10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.
15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.
16. Learning of students and other health care professionals is facilitated.
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital