Stories nails tell.
P.K.Ghatak, MD
Nails are skin appendages. Finger nails are colorless and semitransparent; the blood vessels underneath show through the finger nail-beds. Medical practitioners have been observing and deducting the state of health of their patients for centuries. This examination skill is dying out in present days, due to the use of technologies which are more precise, but not all of them are readily available at the bedside and they increase the cost of medical care.
Fingernails grow about 3.5 mm a month. It takes 6 months for the nail to reach the tip of the finger. So, nails have many stories to tell about the health condition of an individual over a period of the past 6 months. Some of the physicians who described changes in nails as a result from the underlying diseases, have their names attached to those conditions and are sill in use today – a few examples are as follows.
Beau's Lines. Lines form across the nails seen in Raynaud's disease, injuries to the nails and chemotherapy and nutritional deficiency. Cold sensitive constriction of arteries of hands, producing severe blanching of fingers followed by severe pain in fingers and blue discoloration of nail beds and tip of fingers, nose and ears is known as Raynaud's disease.
Muehrcke's Line. In protein deficiency in Nephrotic syndrome, Cirrhosis of liver and famine, white lines develop across the nails.
Drier's disease. An autosomal dominant inherited multisystem disorder appears in late childhood and early adolescence, manifests as short stature, greasy confluent skin rashes, generally in legs, and deformed finger nails with vertical striations.
Color changes indicating underlying diseases:
1. Cyanosis.
Blueish discoloration of nail beds due to hypoxemia can arise from vasoconstriction of vessels of the hands or due to under saturation of arterial blood from diseases of lungs or admixture of venous and arterial blood in the heart chamber due to defects in the partitioning septal walls producing right to left shunt (called Central Cause, in short). In Central Cyanosis, the tongue turns blue. In vasoconstriction, the nail beds are blue, but the tongue remains normal pink color.
2. Methemoglobinemia.
The RBCs carry oxygen in a loose combination with hemoglobin and the iron molecule in the hemoglobin remains in ferrous form; a less than 3 % of oxygen is carried as an oxidized compound – methemoglobin. Here, the iron is oxidized to a ferric form. The ferric iron does not part oxygen to the tissue and tissue suffers from hypoxia. Abnormally high concentration of oxidized hemoglobin in blood may happen following local anesthesia with benzocaine or tetracaine. The nail beds turns gray. Drugs containing aniline, benzene derivatives and nitrite commonly produce similar changes in hemoglobin – most common among the group are dapsone (use of leprosy), nitrates (used for angina pectoris) and benzocaine (local anesthetic).
Congenital Methemoglobinemia.
Navajo and Athabaskan Indian tribes have higher instances of Cytochrome b5 encoding gene mutations and congenital methemoglobinemia. G6PG (glucose 6 phosphate dehydrogenase deficiency) also produces congenital methemoglobinemia.
Hypoxia in methemoglobinemia is not reversed by Oxygen. Methylene blue and other reducing agents are used therapeutically for that purpose.
3. Carbon monoxide poisoning:
Smokers' blood contain a low level of carbon monoxide (CO). Accidental exposure to CO happens in winter months from indoor coal burning or keep a gas cooking range burning through the night for heat. Incomplete burning of coal and natural gas produces CO, and inhaled CO produces high levels of Carboxyhemoglobin in blood. The nails change to cherry red color. Unless promptly treated, CO poisoning is usually fatal or leaves patients with serious neurological deficiencies,
4. Anemia.
Pale finger nails in anemia is a late sign, the tongue and the conjunctive of the lower eyelids become pale much earlier.
5. Obstructive jaundice.
When the bile duct is blocked by gall stones or carcinoma of the head of the pancreas, the bile can not drain into the small intestine, The accumulated bilirubin turns, conjunctiva, skin and nails deep yellow.
Other congenital abnormalities of nails.
1. Yellow nail patella syndrome.
Yellow nail patella syndrome is a multisystem structural abnormalities of skeletal. Dermal and neurological systems. The chromosome 9 carries the genetic mutation which normally encodes transcription factor for early separation of dermatomes into neuroectoderm, ectotherm and mesoderm. All three divisions exhibit developmental abnormalities of varying degrees, however, changes in patella and nail are constant. It is inherited by autosomal dominant mode with variable penetrance. The patella is hypoplastic or often absent, the finger nails are deformed or small and yellow in color and brittle; less frequently toenails are deformed also. Finger joints and elbow joints are hyperextensible. The iliac bones show horn like outgrowths and the neck is long like a swan. The separation of neurons into dopamine and serotonin producing lines are defective. The connective tissue formation around the developing eyes and podocytes of glomerulus of kidney are defective. Some children develop a condition similar to Duchene muscular dystrophy.
2. Nonsyndromic congenital deformed nails condition 10.
This is an autosomal recessive inherited disorder of the EZD6 gene which encodes Frizzld6 protein of nails. Both finer and toenails are extremely thick and hard and easily separates from the nail bed. At times, some toes and fingers are missing.
3. Psoriasis.
Psoriasis is an autoimmune disease of the skin, dead skin cells accumulates under the nail and nails are pitted.
4. Yellow nail syndrome. A rare disease of unknown cause; arires spontaneoulsy and may resolves sponteneously also. It is a combibation of slow growing hard thick and yeollow nail, sinus congestion and lower respiratory tract infection, occasionally associated with cylous pleural effusin and lyphedema of hands and feet.
Genome-wide association showed 60 susceptible regions of genes involved in Thymic 17 cell actions which are linked to psoriasis. Linkage analysis identified 9 additional regions - PSORS 1 to PSORS 9. PSORS 2 is inherited in an autosomal dominant mode and it is the common variant in North America. CARD 14 gene, normally encodes an adapter protein of skin keratinocytes and mutation of this gene is linked to psoriasis.
Nearly 80 % of psoriatic patients have one or more changes in finger nails and also in the toenails. The common presentation is pitted nails. The other changes are white, brown or yellow discoloration, heaped up dead skin underneath the nail separating the nail from the nail bed, and brittle nails. Flame shaped hemorrhagic steaks are occasionally seen.
Fungal infection.
Diabetic patients are more susceptible to fungal infection of toenails and less commonly to finer nails. Dishwashers and other professions in which contact with water is nearly constant are subjects of fungal nail infections. Candida species and Trichophyton fungi are common fungal infection of nails.
Common manifestation of fungal nail infections are change of color to white, black, green or yellow. Thickening of nails are also seen often. Nails become brittle and take unusual shapes and textures. Pain on pressure is a common finding. Toenail fungal infection is much more common in diabetic and workers require wearing boots for long hours.
Systemic illness.
1. Splinter hemorrhages.
Red blood streaks appear under the finger nails due to exude of blood from the capillaries. These are 1 to 3 mm long, run vertically and in multiple nails. Besides bacterial infection of endothelium, leukemia, use of anticoagulants, certain cancer drugs and nail injuries and lupus erythematosus also responsible for splinter hemorrhages.
2. Clubbing.
The fingers normally tapers from palm to fingertip. Clubbing is an acquired deformity of the tip of the finger, appearing like a drum stick with a bulbous end. Many lung conditions results in chronic low blood oxygen produce finger clubbing, chief among them are Bronchiectasis, Non-Small cell cancer of lung, Mesothelioma, Cystic fibrosis, lung abscess. Other less often causes are empyema, amyloidosis, idiopathic pulmonary fibrosis and Sarcoidosis. Some non-pulmonary causes are Coarctation of aorta, aneurysm of subclavian artery, A-V fistula, Congenital heart diseases, Crohn's disease and ulcerative colitis, cirrhosis of liver, malabsorption syndrome, Graves disease of thyroid gland.
Other less frequent nail changes.
Hollowed out nail beds resembling spoons are seen in malnutrition.
A dark gray to black streak along the length should raise suspension of melanoma.
Some people have habits of pushing back the cuticles of nails repeatedly, producing multiple ridges and grooves in the center of nail beds. It is called Onchotillomania.
Half white and half pink nails are common in chronic renal failure patients.
In cirrhosis of liver, nails turn white. White spots on nails are preset in Zinc and iron deficiency
People engaged in silver mining develop blueish nails. In a congenital Copper metabolic disease, Wilson's disease blue mails may be present due to deposition of copper in the tissues.
In vitamin B12 deficiency anemia, nails may turn black in color. In injury to nails, blood under the nail beds appear black. The normal half moon of nail beds may be absent in chronic lung and heart diseases.
Use of hair coloring shampoo usually stains fingernails of varies colors but colors are just stains and can be easily be removed by nail polish remover.
Paronychia.
Paronychia is infection of the soft tissues on the sides of the nail. When the cuticle of the finer nail is damaged, bacteria and fungi grow and an abscess may develop. Paronychia is painful and requires local treatment with antibiotic ointment and rarely incision and drainage of abscess. Streptococcus pyogen and Staph aureus and common bacteria, if damage to the skin is from water, Pseudonymous bacteria is responsible and the pus is green in color. Of the fungi, Candida species is common.
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