Human nails are present on the dorsal aspect of all the fingers and toes. A nail is formed by the living cells presents that are present in the ends of the fingers and toes. It’s structure is shown in Figure 1.
- The nail body or plate: Visible part of the nail that remains attached to the nail bed which represents the skin below the nail.
- The cuticle (Eponychium): It is the tissue that forms the rim of the base of the nail and overlaps the nail body.
- The nail walls or folds: These are the skin folds that supports the nail from three sides.
- The lunula: This forms the whitish half-moon part at the base of the nail.
- The nail root: The nail root forms the matrix which is the underlying structure of the nail found under the cuticle.
Growth rate of the nails
The nails grow from its roots and is made of keratin protein that is also seen in skin and hair. The growing of nails occurs when new cells of the nail matrix are formed pushing the older part of the nail to grow outside the edge of the nail body.
Due to its biological design, the growth rate of a nail is dependent on the age, gender and environmental conditions. The average growth rate of the nails is approximately 0.1 mm per day that is 1 centimeter in 100 days.
Why look at the nails?
The main function of the nails is to protect the ends of the fingers and toes from injury.
Shape, colour and texture can often change with an underlying skin disease or an infection (most often fungal). Although, changes in the nails may not be the first sign of a problem, it can often be accompanied with an underlying health condition which is known or unknown to an individual. Hence, a simple examination of the nails can provide a lot of information about the health and the underlying risk of many conditions.
What should be examined about the nails?
- Changes in the shape of the nails by comparing with the other hand.
- Changes around the nail
- Monitor nail growth
Health problems that are reflected in nails
Abnormal shape and structure of the nail:
Clubbing: This is caused by thickening of the nail plate at the base of the nail due to softening of the nail bed that causes the nail to curve inwards.
It can be found doing a test by keeping the index fingers of both the hands together as shown in Fig 2.
Normally, there should be an angle between the upper skin flesh of the nail and the nail plate forming a diamond shape window. If this window is absent and the angle is lost, it creates the “Schamroth sign” that indicates clubbing.
Clubbing can occur in conditions like:
- Inflammatory bowel disease – inflammatory conditions of the small intestine and the colon involving ulcers that are formed in the intestine.
- Lung diseases: Lung cancer, chronic bronchitis, Chronic obstructive lung diseases – asthama.
- Heart Diseases: Congenital heart disease, heart defects and abnormalities
Koilonychia: This explains wasting of tissue under the nail plate causing the nails to become spoon-shaped as shown in Fig 3.
This shape is seen in conditions like:
- Iron deficiency anaemia – low red blood cells or haemoglobin
- Raynaud’s disease- constriction of blood vessels of fingers and toes due to cold or stress.
- nail-patella syndrome – genetic disorder affecting the nails and the knee caps.
Ripples on nails: This involves pitting of the nails as shown in Fig 4.
This can occur as an early sign of,
- Psoriasis (skin infection with scaly patchy skin problems)
- Arthritis (painful inflammation of the joints).
Beau’s line: Presence of transverse lines or a line on the nail plate as shown in Fig 5,
It can indicate,
- Severe infection
- Heart problem
- Hypotension (Low blood pressure)
- Hypocalcemia (low calcium in the blood)
Cracked thin and brittle nails: This type of nail is shown in Fig 6.
- Thyroid problems
- Metabolic bone disease like osteopenia (loss of bone mass invovingminerals and bone tissue)
Bitten nails or Gnawed nails: Habitual biting of nails or picking causes damage to the nail plate, nail walls and the skin around the nail.
- Chronic anxiety problems
- Obsessive-compulsive disorder
Nail abnormalities related to Colour
Dark lined nail: Blackish dark discolouration seen beneath the nail as shown in Fig 8.
This type of discoloration can be seen among,
- Dark skinned people with pigmentation problems
- Melanoma (skin cancer)
Blue coloured nails:
Bluish discoloration of the nails also called as cyanosis is shown in Fig 9, can indicate a problem with the oxygen-carrying capacity in the blood relating to respiratory problems.
Conditions related to bluish nails:
- Lung problems- emphysema (a lung condition that damages the air sacs in the lungs causing breathing difficulty)
- Heart problems
Yellow coloured nails: Yellowish nails (refer fig 10) can also appear thin and cracked in severe cases.
- Fungal infections
- Severe thyroid disease
- Lung disease
Whitish nails: White nails with a discolored dark rim as shown in fig 11.
- Liver diseases
Nail Beading: Beads formed on the nails look as if it is like melted wax dripping down a candle ( Refer Figure 11).
Conditions related to beaded nails:
- Diabetes mellitus
- Thyroid disorders
- Vitamin B deficiency
What can you do if you find changes in your nails?
- If you see any differences in your nail shape, colour or develop changes in your nails, it could be simply because of any deficiency and not necessarily related to an underlying health condition.
- It is best to consult with a professional in order to get your finger and toe nails examined. You may be asked to undergo a blood test and/or other tests to correctly determine the cause of your health problem.