Interpreting iron studiesBMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2513 (Published 15 June 2017) Cite this as: BMJ 2017;357:j2513
- Alison U Kelly, specialty registrar in chemical pathology1,
- Stephen T McSorley, clinical research fellow2,
- Prinesh Patel, general practitioner3,
- Dinesh Talwar, consultant clinical scientist1
- 1Department of Biochemistry, Glasgow Royal Infirmary, Glasgow, UK
- 2Academic Unit of Surgery, School of Medicine, University of Glasgow, Glasgow Royal Infirmary, Glasgow, UK
- 3Alva Medical Practice, Alva, Stirlingshire, UK
- Correspondence to A U Kelly
What you need to know
•Iron overload typically results in a high ferritin and transferrin saturation
•Iron deficiency is best assessed using serum ferritin, which is low in the absence of inflammation
•Ferritin levels can be elevated by inflammatory processes and can mask iron deficiency
A 63 year old woman visits her doctor with a three month history of fatigue and generalised joint pains. Her medical history is unremarkable and she reports no recent stress, infection, or weight loss. There are no abnormalities on clinical examination. Haemoglobin, creatinine, and electrolytes, liver enzymes, glucose, inflammatory markers, and thyroid function tests are normal. Ferritin, iron, transferrin, and transferrin saturation are also requested.
This article discusses some situations in which ferritin and iron studies might be helpful and how to avoid common pitfalls in their interpretation.
What are the next investigations?
The doctor in this case requested iron studies to investigate the possibility of iron overload and to screen for haemochromatosis. Iron studies are also commonly indicated in clinical practice to investigate iron deficiency, or to monitor response to treatment for these conditions (box 1).
Box 1: Suggested indications for iron studies
iron overload (haemochromatosis)1
o at early stages can be asymptomatic or present with vague symptoms such as fatigue, weakness, or generalised joint pains
o later manifestations might include deranged liver enzymes, cirrhosis, erectile dysfunction, arthritis, or cardiomyopathy
o suspected iron overdose/toxicity
o investigating aetiology of low haemoglobin
o symptoms of anaemia—such as lethargy, shortness of breath, palpitations, pallor, headache, atrophic glossitis, angular cheilosis. Suspected occult blood loss in males and post menopausal females—eg, peptic ulcer disease
o iron malabsorption—eg, investigation of unintentional weight loss or chronic diarrhoea, or secondary to existing conditions such as coeliac disease
o Anaemia in pregnancy (increased iron demands)
o investigation of poor growth in infants
o distinguishing low iron stores from functional iron deficiency—eg, in …