Wednesday, December 15

Yellow skin discoloration - Causes of yellow skin color

Skin discoloration - Yellow skin color
There are many causes for yellow skin color and discoloration and the condition has to be evaluated immediately as some are harmless changes, whereas some are due to serious disorders which can be life threatening, requiring immediate treatment.

Causes of yellow skin color

Certain pigments in the food like carotene get deposited in the epidermal layers when in excess and their presence causes yellow skin color change which is harmless. However, certain disorders of the body systems can interfere with the metabolism of carotene.

These disorders induce carotene deposition and discoloration even though serum levels of carotene are normal, requiring investigation. The excretion of certain medicines through epidermal layers shows up as yellow skin color. The buildup of bilirubin in the blood and the onset of jaundice is due to many diseases and disorders leading to yellow coloration.

Jaundice caused yellow skin discoloration

Jaundice (aka icterus) is yellow pigmentation of the dermal and epidermal layers, sclerae (white of eyes) and mucous membranes. The increased levels of bilirubin in blood plasma (1.5 mg/dL), also known as hyperbilirubinemia, causes jaundice. Hyperbilirubinemia can be due to various factors and categorized into pre-hepatic, hepatocellular and post-hepatic types.

Any of the causes of increased rate of breakdown of red blood cells (hemolysis) leads to pre-hepatic jaundice. Tropical diseases like malaria, genetic diseases like thalassemia, organ disorders like hemolytic uremic syndrome affecting kidney, bilirubin metabolism disorders and high fevers as in leptospirosis (rat fever) causes jaundice and dermal color change.

In hepatocellular jaundice there is usually cholestasis (bile not flowing to duodenum) and the causes are hepatitis of any origin, liver toxicity, genetic disorders like Gilbert's syndrome, alcoholic liver disease and Crigler-Najjar syndrome. Post-hepatic jaundice is usually due to interruption to the flow of bile inside liver as well as to duodenum.

The causes can be gallstones in the bile duct, cancer of pancreas, obstruction by liver flukes, biliary atresia (passage closed or absent), ductal carcinoma (tumor in the duct), pancreatitis (inflammation of the pancreas) and pancreatic pseudocysts (circumscribed collection of fluid rich in pancreatic enzymes, blood, and necrotic tissue). Jaundice discoloration conditions require a combination of liver function tests to arrive at the exact causes and diagnosis.

Newborn and yellow skin color

Mild jaundice is observed in many newborns and this neonatal jaundice is usually harmless. This condition may be seen from second day to eighth day in normal birth and for about two weeks in premature births. It is presumed that apart from higher turnover of red blood cells, physiological and metabolic adjustments after birth, causes this increase in serum bilirubin in newborn.

This increased levels of bilirubin gets lowered with regular urination and bowel movement; hence regular and proper feeding of the baby are very important. However in a few rare cases, neonatal hyperbilirubinemia causes kernicterus, a brain-damaging condition, resulting in lifelong disability.

To avoid this risk it is better to treat the neonatal jaundice by exposing the baby to intense photo-therapy. Inadequate feed, infections, internal bleeding or liver disorder or malfunction or incompatible Rh blood factors of mother and child can also lead to skin discoloration requiring proper treatment.

Primary carotenoderma

Ingesting food containing high levels of carotenoids leads increased serum levels of carotene and its deposit in the skin. Carotenoids are deposited in the intercellular lipid containing spaces in stratum corneum.

Thick epidermal layers and regions of increased sweating like nasolabial folds, palms, knees and soles bear increased deposits and show greater color change. Carotenoderma differs from yellow color due to bilirubin in not showing coloration of white of eyes. Primary carotenoderma yellow color usually disappears after the reduction in intake of carotenoids.

Secondary carotenoderma

Usually a underlying disease condition causes increase in serum levels of carotene and secondary carotenoderma discoloration, though the carotene intake is normal. Kidney malfunction or dysfunction is usually associated with decreased excretion of carotenoids and hypercarotenemia and color change.

Impaired conversion of carotenoids to retinol is seen in diabetes mellitus and hypothyroidism. The associated increase in serum lipids as seen in diabetes mellitus, nephrotic syndrome and hypothyroidism causes yellow skin color and secondary carotenoderma. In Anorexia nervosa, a self-imposed starvation, diets may be rich in carotene. Liver disease also leads to yellow color change due to poor utilization and breakdown of carotene resulting in its increased serum levels.

Yellow skin color due to medicines

The use of certain medicines in the treatment of diseases causes yellow coloration. Tyrosine kinase inhibitors (TKIs) are used in the treatment of various cancers. Sunitinib (a TKI) used in the cancer therapy is associated with many adverse events and yellow color changes of the epidermal layers. Color changes start after a week of treatment and with the continuation of the treatment, color intensification has been noticed.

The sclerae and mucous membranes are spared of the color change and on the discontinuation of medicine resolves the coloration. Probably the excretion of the chemical via the epidermis causes this coloration. Another TKI, sorafenib also causes a diffuse yellow discoloration of the skin.

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