As lot of clinical signs are reflected in the nails it is considered as a marker of various systemic diseases
Various abnormalities are seen in nail which include
1.Change in the shape of nail
Clubbing
Koilonychia is dry brittle spoon shaped nail ,in the early stages there is flattening of nail. This is seen in iron deficiency anemia.
Plummer's nail
Brittle nail with longitudinal ridges and distal onycholysis seen in hypothyroidism
2.Different lines in nail
Beaus line
Transverse furrow in the nail plate due to temporary arrest of of nail growth this is seen in association with serious systemic disease
Mees lines
White transverse band in nail plate seen in arsenic poisoning and septicemia.
3.Change in nail colour
Lindsay nail Half half nail
Seen in chronic renal failure
There is proximal dull white portion and distal pink or brown portion with a well demarcated line of
separation
Leuconychia
Whitenail or Terry's nail is seen in hypoalbuminemia in cirrhosis and nephrotic syndrome.
Blue nail
Azure lunule-bluish discoloration of lunule of nail seen in Wilson's disease.
Yellow nail syndrome
Comibination of yellow nail, broncheictasis and nephropathy.
Glassy nails are seen in cirhhosis of liver
Discoloration of nail is produced by drugs like busulphan, zidovudine, phenothiazine, antimalarials and antibiotics.
4.Bleeding manifestation
Splinter haemorrhage is linear subungual hemorrhage away from free nail margin it seen in infective endocarditis and trichinosis.In infective endocarditis it is vertical haemorrhage and and in trichinosis it is horizontal
Nail bed infarct observed in Vasculitis - SLE, PAN.
Nail fold telangiectasia: Periungual telangiectasia, PSS, SLE, dermatomyositis.
Pitting of nail is seen in Psoriasis.
Onychomyosis is the fungal infection of nail
Distortion of nail growth
Nail growth is distorted in ectodermal dysplasia, chondroectodermal dysplasia, and nail-patella syndrome.