What is it?
Pallor means an abnormal paleness of the skin or mucous membranes.
What factors affect pallor?
Paleness may be normal for some people, and does not always imply an underlying illness. The overall appearance of the skin is affected by many factors, such as
- Pigment – in dark-skinned people, pallor may be difficult to detect, and may only be noticeable in the eyes or inside the mouth.
- Visibility of blood vessels – thin skin allows the colour of blood vessels to be seen.
- State of blood vessels – when very cold, the peripheral vessels contract restricting blood supply, making hands, feet and digits look pale. Shock can give the same picture.
- Content of blood vessels –if there is too little blood in the vessels (acute or chronic blood loss), or the blood has too few red cells, (anaemia), pallor results.
- Lack of sun exposure – sun-exposed skin becomes tanned, hiding pallor.
Pallor may affect the whole body or only parts, for instance an arm or a leg, and there may be associated symptoms such as pain in a limb, shortness of breath, fast pulse rate and fainting.
In an otherwise well and healthy person, pallor may be unimportant, unless it is also seen in the eyes and mouth, or localised to a body part. These patients will need investigating.
Clinically significant pallor means anaemia, which has many possible underlying causes:
- too few red blood cells in the circulation due to
- insufficient production – bone marrow problems, or deficiency states
- excessive loss – bleeding, or increased breakdown of the cells
- ineffective red cells as in deficiency states (B12, iron, folate)
- abnormal red cells, as in the leukaemias
- chronic disease states – ongoing diseases block the efficient production of red cells, mainly by interrupting the uptake and use of iron
Clinical findings in a patient with pallor will guide the doctor towards a diagnosis. However, objective measurement is needed to help establish the diagnosis of anaemia, identify the type (cause), and to select and monitor treatment.
Within each red blood cell is a protein molecule, haemoglobin (Hb), which is used to carry oxygen. If there is too little Hb, if it is abnormal (some genetic disorders), or if it is in any way prevented from carrying oxygen (toxic states), anaemia may result.
A quick Hb screening test can be done in the doctor’s rooms or clinic: a drop of blood from a finger-prick is inserted into a haemoglobinometer (Hb meter), which gives an immediate reading. This is checked against a chart of normal values for gender, age and so on. This is not a very accurate test, but does give an indication.
A formal full blood count (FBC) done by the laboratory will give more reliable and detailed information. For this, blood is drawn from a vein in the standard way, placed into a special tube coated with an anti-clotting agent, and sent to the lab. Most of the test is done by automated machines, and the results are available on the same day. The FBC gives values for:
- Hb levels and concentration within the red cell;
- The number of red cells and what percentage of the total blood volume they comprise;
- The size of the red cells, which is relevant in diagnosing deficiency states;
- The number of white cells present, and a breakdown of the different types – this is relevant in infections, chronic illness and leukaemias;
- The number of platelets; and
- The presence of abnormal cells.
A smear of the blood sample is also analysed by a technician, who reports on the appearance and quality of all the cells seen in the blood.
Depending on the finding of the FBC, other tests may be necessary. Specialised blood tests may be ordered to identify chronic or auto-immune diseases, liver disease ( including alcohol-induced states), kidney disease, states of abnormal red cell breakdown, or to confirm deficiency states (like ferritin tests for iron deficiency). Bone marrow tests may be indicated for white cell abnormalities.
Pallor not linked to any underlying disorder requires no treatment.
Further management depends on the identified cause, for instance vitamin/iron supplements, or managing the cause of blood loss.
(Dr AG Hall)