Anaemia and low iron

 

Anaemia is an abnormally low level of haemoglobin in the blood. Haemoglobin carries oxygen but the red cells also maintain the fluid balance around the body. Anaemia is relatively common and even in the developed world exists in up to 5% of the population. It is now agreed that the ideal haemoglobin for major surgery is 130 g/L or more. Previously we have used grams per decilitre and 130 g/L is 13 g/dL

For minor operations anaemia does not appear to be a significant problem. Indeed haemoglobin as low as 80 does not affect oxygen delivery around the body and may reduce the risk of deep vein thrombosis and pulmonary emboli. However for more major surgery where there is a risk of blood loss which would require replacement with a blood transfusion anaemia is a major risk. For patients undergoing cancer surgery, orthopaedic surgery, and cardiac surgery anaemia increases morbidity and mortality. Even with safe donor blood as exists in the UK, blood transfusion itself increases morbidity and mortality.

We now have a recognised protocol in the UK for patients undergoing major surgery. Every patient should have their haemoglobin measured as early as possible and certainly at least six weeks before surgery. Patients can play an important role in reminding their surgeons or GPs to take a blood sample. Patients whose haemoglobin is below 130 should be given four weeks of iron tablets after which the haemoglobin is rechecked. If the haemoglobin is still below 130 there is then time to consider giving intravenous iron or erythropoietin to ensure the haemoglobin is over 130 at the time of surgery.

For some patients intravenous iron is the first choice: these include anaemic patients with chronic renal failure because intravenous iron produces a higher haemoglobin than the oral route. It also includes patients with ulcerative colitis, Crohn’s and IBS because oral iron will change the gut flora which exacerbates these diseases.

If a patient is anaemic, the most likely reason is iron deficiency. In women this is most commonly due to heavy periods or menorrhagia. Other causes include haemoglobinopathies such as sickle cell disease or thalassaemia, diet, renal disease, chronic inflammatory diseases such as rheumatoid arthritis and lupus, liver disease and cancer. It is important that patients are properly investigated and the UK guidelines now have a simple flowchart so that every doctor should be able to identify the likely cause and refer the patient to the relevant specialist for further investigations.

It is possible to have a normal haemoglobin but inadequate iron stores. This is called iron deficiency. There are specific subsets in children and pregnant women which are outside this blog. Symptoms include fatigue, poor memory and attention. Signs include a smooth tongue, brittle nails and poor hair and skin condition. The problem is that both the symptoms and signs are very common in patients who do not have iron deficiency. The diagnosis is normally made by measuring ferritin levels with a blood test but this should only be done in patients who are not anaemic as many of the causes of anaemia make the test unreliable. Heart failure, alcohol and hyperthyroidism also give abnormal readings so it is important to be careful with the diagnosis and to ensure that treating patients thought to have iron deficiency does actually improve their symptoms before possibly committing them to lifelong treatment.

Ideally, treatment should only follow proper assessment and further investigations. Initial treatment is normally with iron tablets and absorption can be improved by simultaneously taking ascorbic acid tablets. Calcium, which is high in dairy products, and possibly tea and coffee reduce absorption and should be limited.

A minority of patients with iron deficiency cannot be treated with oral iron. This may be due to side effects such as constipation, diarrhoea or abdominal pain while some patients do not absorb enough iron. These patients should be considered for intravenous iron which will need to be repeated to maintain ferritin levels. Historically we have been cautious of giving intravenous iron because of the fear of anaphylactic or allergic reactions but the US Centre for Health Statistics has calculated that there is only one death for every five million doses. Certain patients should not be offered intravenous iron and these include patients with hypersensitivity or atopy (which includes allergies, asthma or hayfever) as well as patients with chronic inflammatory disease such as rheumatoid arthritis or lupus. Elderly patients, patients on beta-blockers or ACE inhibitors as well as patients with respiratory and cardiac diseases should be considered at higher risk although this may be simply because an allergic reaction would be more difficult to manage.

The treatment of anaemia and iron deficiency therefore needs careful management and adherence to the latest protocols as well as the treatment of any underlying cause, but although intravenous iron should never be given as a first line treatment in most patients and certainly isn’t inherently ‘better’ than oral iron, it is considered safe to be offered to a minority of patients following informed consent and with ongoing monitoring.

Intravenous iron should always be given in hospital so that any allergic reaction can be managed quickly and competently. Reactions can occur after many uneventful infusions so I do not believe it is safe to give iron infusions out of hospital on the basis that there have been no problems in the past. Some people give iron infusion in clinics and surgeries but I consider this unwise because in the event of an allergic reaction a full resuscitation team with comprehensive monitoring and support equipment is required as well as the full range of anaphylactic drugs that are only found in a hospital setting.

Weymouth Street Hospital, where I work and am a director, is happy to administer intravenous iron on a daycase basis. The website is https://www.phoenixhospitalgroup.com/