UK: The British Society for Haematology (BSH) has released an updated guideline on the laboratory diagnosis of iron deficiency in adults (excluding pregnancy) and children. The guideline appears in the British Journal of Haematology.
As iron homeostasis is dynamic, the laboratory diagnosis of iron deficiency is difficult. No single test can provide an accurate assessment of iron absorption, transport, storage, and utilization.
"The different assays available to assess iron and its stores will each be discussed, and recommendations made pertinent to practice within the UK. Iron metabolism in children and adults can be considered equivalent and these recommendations are applicable to both pediatric and adult practice," the authors wrote.
Hemoglobin concentration and red cell parameters (HcT, MCV, MCH, MCHC, RDW)
If thalassaemia is not present, then any of MCV, MCHC or MCH below the normal range could suggest iron deficiency.
Normal red cell indices do not exclude iron deficiency as a cause of anaemia, so further investigation may still be required if there is a high level of clinical suspicion.
Advanced red cell indices
Mean reticulocyte Hb content of <29 pg can support the diagnosis of iron deficiency if initial tests are inconclusive.
Blood cell morphology
Inspection of a peripheral blood film should be performed in cases of diagnostic uncertainty.
Serum ferritin
Serum ferritin of <12 μg/l in children aged < 5 years and <15 μg/l in those aged > 5 years is indicative of iron deficiency.
Serum ferritin within the laboratory reference range cannot exclude iron deficiency in the context of raised inflammatory markers or a history of acute or chronic disease, so further investigation may be warranted.
Iron studies: serum iron, total iron binding capacity (TIBC) and transferrin saturation (TSAT)
Serum iron studies should not be used in assessment of iron deficiency other than to calculate the TSAT.
SAT of <16% can support the diagnosis of iron deficiency if initial tests are inconclusive.
Soluble transferrin receptor (sTfR)
The sTfR assay is not recommended for investigating iron deficiency.
Zinc protoporphyrin (ZPP)
Measurement of ZPP is not recommended for the diagnosis of iron deficiency.
Hepcidin
Measurement of hepcidin is not currently recommended for investigating iron deficiency.
"We expect the evidence base for use of other tests such as hepcidin to evolve over the next few years allowing further development of this algorithm," the researchers concldued.
Reference:
"Guideline for the laboratory diagnosis of iron deficiency in adults (excluding pregnancy) and children," is published in the British Journal of Haematology.
DOI: https://onlinelibrary.wiley.com/doi/10.1111/bjh.17900