The nails are present at the end of each fingertip on the dorsal surface. The primary function of the nail is protection, and it also helps for a firm grip for holding articles.
It consists of a durable, 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. A regular healthy nail is slight pink in color, and the surface is convex from side to side. Fingernails grow 1 cm in three months, and toenails take 24 months for the same.
Importance of nails in disease diagnosis:
The color, 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 conditions. 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.
We can make out an unhygienic nail very quickly. The deposition of dirt under the distal end of the nail plate can make a chance for the ingestion of pathogens while eating.
If nail cutting is not done correctly, 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 anemia.
b) Opaque white discoloration (leuconychia) is seen in chronic renal failure and nephrotic syndrome.
c) Whitening is also seen in hypoalbuminemia as in cirrhosis and kidney disorders.
d) Drugs like sulpha group, anti-malarial, and antibiotics can produce discoloration in the nails.
e) Fungal infection causes black discoloration.
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 hemorrhages in subacute bacterial endocarditis, rheumatoid arthritis, trauma, collagen vascular diseases.
i) Blunt injury produces bleeding and causes blue/black discoloration.
j) Nails become brown in kidney diseases and decreased adrenal activity.
k) In Wilson’s disease, blue color 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) The 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:-
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, and etc.
Here the nails become concave like a spoon. This condition is seen in iron deficiency anemia. In this condition, the nails grow thin, soft, and brittle. The average 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 discoloration, deformity, hypertrophy, and abnormal brittleness.
b) Thimble pitting of nail is characteristic of psoriasis, acute eczema, and alopecia aerate.
c) The inflammation of the 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 the 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.
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.