Pallor accompanies a number of pathological conditions, but in many people, however, pale skin color is normal and its evaluation also depends on subjective impression of a physician. The overall perception of skin color is influenced primarily by showing through subcutaneous blood vessels filled with blood and by a dark pigment called melanin in the skin.
Lack of sunshine
Skin color of Caucasian population race depends largely on exposure to sunlight. A dark pigment called melanin stains the skin brown (or black) and its formation is dependent on sunlight exposure. Caucasian people are pale when not exposed to the sun. The content of melanin in the skin is moreover individual and genetically influenced; therefore some people are whiter “by nature”.
Significant anemia is associated with overall pallor of skin and mucous membranes. Quite well is this condition seen in eye conjunctiva, skin color is not so reliable. The essence is the lack of blood pigment hemoglobin (and usually deficiency of red blood cells) that causes blood red color showing through the skin and mucous membranes. Pallor is usually accompanied by other symptoms of the anemic syndrome such as shortness of breath, fatigue and dizziness. For details, see the relevant article about anemia.
Regardless of the underlying cause the majority of shock conditions are inevitably associated with pale color of skin. This is due to a narrowing of small blood vessels in the skin as a regulatory response of our organism against blood pressure decrease. Skin circulation is evaluated as less important and therefore it is reduced.
Human skin pales when getting cold for similar reasons as mentioned in previous case – there is a tendency to narrow skin blood vessel. It's part of a defensive reaction to prevent heat loss. Small blood vessels under the skin can easily radiate heat to surroundings and the body tries to avoid this. Frostbite may be a complication of chilling cold impact combined with reduced skin blood perfusion.
Decrease of blood glucose level is associated with activation of defense mechanisms of the organism ensured by hormones such as adrenaline. Due to these mechanisms blood flow through skin is reduced.
Local pallor is present in situations when a certain part of the body looses the inflow of arterial blood. Most often it is the result of an artery closure by a blood clot. It is almost always a medical emergency condition that must be solved as soon as possible. In addition to the pallor of affected body part (usually it is a limb), strong limb pain and its coldness emerge. Disruption of nerves by lack of oxygen causes sensitivity or even mobility disorders. Treatment must be quick and aggressive and prevent local necrosis. Anticoagulants are used to prevent blood clot growth and then the blood clot itself must be removed either by special thrombolytic drugs, or by endovascular or surgical approach. If the affected limb is no longer capable of life, its amputation must be executed.
Note: Local little arterial closures with pale finger segments on upper extremities are typical for a condition known as Raynaud’s phenomenon.
This is a very rare cause of pallor that is associated with genetically related impaired pigmentation. The term “albinism” refers to a whole group of diseases.
This congenital metabolic disease affects metabolism of the amino acid phenylalanine that is necessary for skin pigment formation. Pallor, blue eyes and blond hair are therefore main symptoms of children with this disease.
A patient usually doesn’t visit his or her doctor because of pallor; it is more often a secondary finding by a patient with other problems. During physical examination it is important to check the color of conjunctiva and perform a digital rectal exam to rule out acute gastrointestinal bleeding with blood in stool. The severity of possible anemia can be assessed from blood tests.