Introduction:
The nails are present at
the end of each fingertip on the dorsal surface. The main function of the nail
is protection and it also helps for a firm grip for holding articles. It
consists of a strong relatively flexible keratinous nail plate originating from
the nail matrix. Under the nail plate, there is a soft tissue called a nail
bed. Between the skin and nail plate, there is a nail fold or cuticle. Normal
healthy nail is slight pink in colour and the surface is convex from side to
side. Finger nails grow 1 cm in three months and toenails take 24 months for
the same.
Importance of nails in
disease diagnosis:
The colour, appearance, shape
and nature of the nails give some information about the general health and
hygiene of a person. Nails are examined as a routine by all doctors to get some
clues about underlying diseases. Just looking at nails we can makeout the
hygiene of a person. The abnormal nail may be congenital or due to some
diseases. The cause for changes in the nail extends from simple reasons to life-threatening
diseases. Hence the examination by a doctor is essential for diagnosis. Some
abnormal findings with probable causes are discussed here for general
awareness.
1) Hygiene:-
We can make out an
unhygienic nail very easily. Deposition of dirt under the distal end of the nail
plate can make a chance for ingestion of pathogens while eating. If nail
cutting is not done properly it can result in worm troubles in children. When
the worms crawl in the anal orifice children will scratch which lodges the ova
of worms under the nails and will be taken in while eating. Prominent nail can
also complicate a skin disease by habitual scratching. Sharp nails in small
kids cause small wounds when they do feet kicking or hand waving.
2) Colour of the nails:-
a) Nails become pale in
anaemia.
b) Opaque white
discolouration(leuconychia) is seen in chronic renal failure and nephrotic
syndrome.
c) Whitening is also
seen in hypoalbuminaemia as in cirrhosis and kidney disorders.
d) Drugs like sulpha
group, anti-malarial and antibiotics etc., can produce discolouration in the
nails.
e) Fungal infection
causes black discolouration.
f) In pseudomonas
infection nails become black or green.
g) Nail bed infarction
occurs in vasculitis, especially in SLE and polyarteritis.
h) Red dots are seen in
nails due to splinter haemorrhages in subacute bacterial endocarditis,
rheumatoid arthritis, trauma, collagen vascular diseases.
i) Blunt injury produces
haemorrhage and causes blue/black discolouration.
j) Nails become brown in
kidney diseases and decreased adrenal activity.
k) In Wilson's disease,
blue colour in semicircle appears in the nail.
l) When the blood supply
decreases nail become yellow. In jaundice and psoriasis also nail become
yellowish.
m) In yellow nail
syndrome, all nails become yellowish with pleural effusion.
3) Shape of nails:-
a) Clubbing: Here
tissues at the base of nails are thickened and the angle between the nail base
and the skin is obliterated. The nail becomes more convex and the fingertip
becomes bulbous and looks like an end of a drumstick. When the condition
becomes worse the nail looks like a parrot beak.
Causes of clubbing:-
Congenital Injuries
Severe chronic cyanosis
Lung diseases like
empyema, bronchiectasis, carcinoma of bronchus and pulmonary tuberculosis.
Abdominal diseases like Crohn's
disease, polyposis of colon, ulcerative colitis, liver cirrhosis etc...
Heart diseases like Fallot's
tetralogy, subacute bacterial endocarditis, etc..
b) Koilonychia:-
Here the nails become
concave like a spoon. This condition is seen in iron deficiency anaemia. In
this condition, the nails become thin, soft and brittle. The normal convexity
will be replaced by concavity.
c) Longitudinal ridging
is seen in Raynaud's disease.
d) Cuticle becomes
ragged in dermatomyositis.
e) Nail fold
telangiectasia is a sign in dermatomyositis, systemic sclerosis and SLE.
4) Structure and consistency:-
a) Fungal infection of
nail causes discolouration, deformity, hypertrophy and abnormal brittleness.
b) Thimble pitting of
nail is characteristic of psoriasis, acute eczema and alopecia areata.
c) The inflammation of
cuticle or nail fold is called paronychia.
d) Onycholysis is the
separation of nail bed seen in psoriasis, infection and after taking
tetracyclines.
e) Destruction of nail
is seen in lichen planus, epidermolysis bullosa.
f) Missing nail is seen
in nail-patella syndrome. It is a hereditary disease.
g) Nails become brittle
in Raynaud's disease and gangrene.
h) Falling of nail is seen
in fungal infection, psoriasis and thyroid diseases.
5) Growth:-
Reduction in blood
supply affects the growth of nails. Nail growth is also affected by severe illness.
when the disease disappears the growth starts again resulting in the formation
of transverse ridges. These lines are called Beau's lines and are helpful to date
the onset of illness.