In medicine, things are often not as they seem. Medical students have this point hammered home again and again during their training. At examinations, they are faced with realistic glass eyes and patients whose organs are transposed. So, a student claiming to have seen a pupil react to light when the eye in question is solid glass learned the painful lesson to always describe what you see - not what you think you should see.
Facial colour is a case in point. Do you describe someone who is pale as anaemic? Is the patient with a yellow complexion always jaundiced?
A patient of mine tells a good story to illustrate how unreliable facial colour can be as a sign of illness. She began to get phone calls from worried family members, telling her that her dad looked "deathly pale". Subsequently at a family wedding, people remarked at how "unwell, tired and drawn" he was. She resolved to approach her mother to see if he was okay and if there was anything amiss.
"Oh, that's the factor 35 sunscreen he's being using all summer," she replied. "I've been telling him he looks ridiculous, but he says he's determined not to get skin cancer!" Sure enough, when his daughter took a closer look the pallor ceased abruptly in a line around his neck and ears. As the Irish proverb puts it, "Ni mar a shiltear a bhitear".
So how are you to know whether you or someone close to you is anaemic? A pallor of the inner surface of the eyelid or the underside of the tongue is what doctors are taught to look for. However, in medical trials, the reliability of these signs has been found wanting.
The only accurate measurement of anaemia is a blood test. Referred to as a full blood count (FBC), it measures the haemoglobin (Hb) levels in the blood. Haemoglobin is the pigment in the red cells which carries oxygen around the bloodstream. If your levels of Hb are low, then you have anaemia.
Just to complicate the picture, there are different types of anaemia. Doctors classify them as microcytic, normocytic or macrocytic. "Cytic" refers to the red blood cells - in microcytic anaemia the cells have shrunk in size. Macrocytic cells are larger than normal and in normocytic anaemia these cells have remained a proper size but their oxygen-carrying capacity is still impaired.
From a practical point of view, it is easier to equate these three types of anaemia with a cause. People with iron deficiency anaemia usually have the microcytic type. People with anaemia secondary to long-standing chronic disease will usually have normal-sized, red blood cells. And macrocytic anaemia is most commonly a result of vitamin B12 or folic acid deficiency.
Regardless of the type of anaemia, the symptoms remain the same. Breathlessness, headaches, a feeling of "tiredness all the time" are the commonest complaints. If you suffer from angina or a respiratory problem, they can be worsened by anaemia. A soreness or cracking of the tongue and the sides of the mouth are found in some types of the disease. Anaemia is not always severe enough to cause symptoms and may only come to light when an FBC is performed as part of a routine check up.
Discovering anaemia and its type is often just the beginning of the diagnostic process. Iron-deficiency anaemia in women is usually caused by heavy menstrual loss or pregnancy. Provided they respond to iron replacement therapy, there is no need for further investigation. Iron deficiency anaemia in a man is less easily explained. The doctor will usually organise a series of tests to ensure that there is no blood loss occurring in the stomach or bowel.
Treatment of iron deficiency anaemia is straightforward and involves taking oral iron, which allows the bone marrow to make red blood cells with normal amounts of haemoglobin. There is a slow return to normal levels of haemoglobin, although it is usually a good idea to continue taking iron for about three months afterwards, in order to replace iron stores in the body.
Macrocytic anaemia is often found to be caused by vitamin B12 deficiency. More commonly referred to as pernicious anaemia, this comes from a time when the cause was unknown and it often led to the death of the patient. Now, however, it can be diagnosed and treated quite easily, so the name pernicious is no longer appropriate.
When the body is short of vitamin B12, the red blood cells lack the essential ingredient to divide and make new cells; the numbers gradually dwindle giving rise to a low haemoglobin and anaemia.
Shortage of vitamin B12 can be dietary or it can arise because of bowel disease affecting the part where the vitamin is normally absorbed. A common cause is surgery to remove part of the stomach, which results in the loss of a substance essential for vitamin B12 absorption further down the digestive system. Vitamin B12 is replaced by regular injection.
Chronic illness of any kind can cause a low grade anaemia with no specific cause.
Sickle cell disease is a form of anaemia we may see more of in this country. Refugees from countries in Asia, the Mediterranean and the Caribbean, where sickle cell disease is common, are prone to developing acute illness when a clumping or stickling of their red blood cells occur. Lack of fluids, infection, pregnancy and anaesthesia can bring on a so-called sickle cell crisis.
Anaemia is easily treated, no matter what the cause. The challenge, as many doctors will testify, is in making the diagnosis in the first place.
Contact Dr Houston at mhouston@irish-times.ie or leave messages on tel 01-6707711, ext 8511.
