Iron deficiency

South Tees Hospitals NHS Foundation Trust

Definition/Description

Iron deficiency often shows as a hypochromic microcytic anaemia (low MCH and MCV) with a low ferritin value.

Diagnostic problems can occur in the presence of an acute or chronic inflammatory condition. This can cause a falsely elevated ferritin despite true iron deficiency. Inflammation can also cause anaemia of chronic disease with a mildly low MCV/MCH and low serum iron despite normal iron stores. This picture may become easier to interpret if the underlying disease can be controlled.

Anaemia with a markedly low MCV/MCH can also be seen with a haemoglobinopathy. Consider if the MCV/MCH is lower than expected, normal ferritin and usually non-Caucasian ethnicity. The laboratory will normally automatically add haemoglobinopathy screening in this situation.

Red Flag Symptoms

None provided.

Guidelines on Management

Differential Diagnosis:

Blood loss - most commonly gastrointestinal (NSAIDs or pathological lesion) or gynaecological / menstrual. Unusual causes such as hookworm after travel.
Malabsorption - such as coeliac disease, gastrectomy or gastric bypass.
Poor intake - unusual as a sole cause except with extreme diets.
Pregnancy - common, although serum ferritin falls in 2-3 rd trimesters due to dilution and redistribution. A ferritin value <30ug/L should prompt replacement therapy.

Examination:

Abdominal examination, including rectal exam if tenesmus or bleeding.
Gynaecological examination as appropriate.

Baseline investigations:

FBC, blood film (elliptocytes or pencil cells suggest iron deficiency), ferritin. Check inflammatory markers if ferritin unexpectedly normal (if concurrent inflammation, a ferritin >100ug/L normally excludes iron deficiency except in severe inflammation, while a value <50ug/L is suspicious but not diagnostic).
Coeliac serology in all cases of iron deficiency anaemia
Urinalysis
Consider the possibility of atrophic gastritis (anti-parietal cell / anti-intrinsic factor antibodies) or H. pylori infection (faecal antigen test) as a cause of unexplained or refractory iron deficiency anaemia.
Faecal occult blood / faecal immunochemical testing neither confirms nor excludes gastrointestinal pathology. Stool parasite testing may be suggested based on travel history.

Treatment:

Standard treatment is ferrous sulphate 200mg OD or ferrous fumarate 210mg OD until anaemia resolves (Hb should rise by 20g/L in 3-4 weeks), then a further 3 months to build iron stores. Monitor blood count 3 monthly for 1 year.
If intolerant of ferrous sulphate / fumarate then try alternate iron preparations (e.g. ferrous gluconate). These may be better tolerated although the iron content may be lower. Avoid slow release or enteric coated preparations.
Iron is also better tolerated (although less well absorbed) if taken with food. Avoid taking with calcium or phosphate containing foods / drinks / supplements, cereals, eggs, tea / coffee or high fibre foods.
A small glass of orange juice (or ascorbic acid 250mg) may improve absorption, while medications to reduce gastric acid reduce absorption.

Referral Criteria/Information

Referral:

The majority of patients will require referral to Gastroenterology to look for an underlying cause:
- All men and post-menopausal women unless obvious non-GI cause.
- Pre-menopausal women with colonic symptoms, strong family history of GI cancer, refractory iron deficiency, or if not menstruating.
2WW if age >60yr and unexplained IDA, positive FIT test or concerning clinical features (e.g. consider urgent referral if <50yr and rectal bleeding).
Consider Gynaecology referral based on symptoms. 2WW if age >55yr and post-menopausal bleeding
Haematology referral if considering parenteral iron therapy- i.e. unresponsive or intolerant of oral iron. Patients will still need referral to Gastroenterology / Gynaecology to identify and treat the underlying cause.