Sysmex Europe

Scientific Calendar October 2022

The challenges of preoperative iron deficiency on surgical patients

Which parameter can help to evaluate the patient’s erythropoiesis and iron status in real time?






That's the correct answer!

Sorry! That´s not completely correct!

Please try again

Sorry! That's not the correct answer!

Please try again


Please select at least one answer

Scientific background

Patient blood management (PBM) is a patient-centred medical concept addressing anaemia, blood loss, iron deficiency and coagulopathy as risk factors for adverse effects in surgical and non-surgical patients [1]. Therefore, PBM is a key pillar in the individual patient’s preoperative anaemia assessment. The lingering question is: Does the patient’s bone marrow produce enough blood cells to supply the body, cover potential loss during or after surgery, and ultimately prevent a hospital-acquired anaemia?

Anaemia affects up to one third of the general population and can turn from mild symptoms such as fatigue and shortness of breath to a severe organ impairment requiring immediate therapeutic interventions [2]. To determine whether anaemic conditions are present the haemoglobin level is checked. Iron deficiency is the most common cause for decreased or impaired red blood cells, but hospital-acquired anaemias are another rising concern [3]. In the case of hospital-acquired anaemia, patients have normal haemoglobin levels at admission (preoperatively) and lose a significant volume of blood over the course of the hospital stay – potentially up to a health-threatening level.

To illustrate and quantify the scope of the blood loss, cardiothoracic patients at a hospital in the United States were monitored [3]. The group found that over the course of an average hospital stay of one week a cardiothoracic patient undergoes an impressive number of more than 100 laboratory tests. Such a patient loses on average 500 mL blood – quite a significant amount, which may rise to a litre depending on the severity of the disease and length of hospital stay. Ultimately, such a developing hospital-acquired anaemia is associated with increased complication rates and mortality.

The phenomenon of hospital-acquired or so-called ‘iatrogenic’ anaemia affects around 25% of hospitalised patients regardless of the reason for admission [4]. In general, anaemias are not only frequent but also often tricky to identify. There is not ‘the one’ parameter reflecting the iron and anaemia status directly. For example, in case of underlying inflammatory processes markers such as ferritin are not diagnostically conclusive. The haematological parameter RET-He provides a real-time assessment of iron availability because it reflects the haemoglobinisation of reticulocytes [4, 5]. Hence, RET-He is an aid in a patient’s preoperative anaemia assessment. An early identification of anaemia helps to provide either nutritional support to enhance the iron supply or intravenous iron administration, both of which are established tools to address preoperative anaemia.

To save patient blood as well as transfusion units, the implementation of PBM concepts becomes more and more prominent [4, 5]. This includes process optimisation programmes to reduce the frequency and volume of blood draws, and the utilisation of effective parameters such as RET-He.

In our case of the month, we introduce a patient whose iron status and erythropoiesis efficiency is preoperatively determined using advanced red blood cell parameters from the RET channel, which can be very helpful to consciously manage the patient’s needs throughout the hospital stay.

Patient information

A 75-year-old male patient was hospitalised anticipating a total knee replacement surgery due to advanced osteoporosis in the joint. Already a year before, he had his first knee completely replaced. Back then he had an established iron deficiency anaemia (IDA) detected before the surgical procedure. Hence, he received erythropoiesis-stimulating agents (ESA) and ferumoxytol, an intravenous iron drug, aiming to balance the IDA. This time, he had his blood drawn and analysed up front to check his preoperative iron status.

Numeric results

Under the assumption that the preoperative management of the previous year would have to be repeated, the patient’s iron status was analysed carefully. The CBC revealed indeed decreased values for RBC and HCT. The most important marker to check whether an anaemia is present, the haemoglobin, was low but within range.

Also, the reticulocyte haemoglobin equivalent (RET-He) indicated the patient’s normal iron levels. The advanced clinical parameter RET-He detects changes in the iron status of the erythropoiesis far earlier [5]. Since red blood cells have a 120-day lifetime, classical haematological parameters such as HGB, HCT and RBC allow only a relatively late detection of iron deficiencies and changes in the iron status of erythropoiesis.

Moreover, the absolute count and the percentage of the patient’s reticulocytes were within range, underpinning that his bone marrow worked well and a decent number of reticulocytes were being produced.

Therefore, no administration of ESA and iron were necessary this time. With this approach, the parameter RET-He helps to spare the patient unnecessary therapeutic interventions and at the same time supports patient blood management.

Table: Blood analysis results for determining whether preoperative iron deficiency-related therapy is necessary

Parameter Result Reference range Interpretation
RBC 3.22 x 1012/L 4.3 – 5.6 x 1012/L [6] low
HCT 33.6% 40 – 50% [6] low
HGB 13.7 g/dL 13.7 – 16.5 g/dL [6] within range
RET-He 38.8 pg ≥ 28.5 pg [7] high
RET% 1.86% 0.68 – 1.86% [6] within range
RET# 102 x 109/L 34 – 102 x 109/L [6] within range



[1] WHO (2021): The urgent need to implement patient blood management. Online:

[2] WHO (2011): Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. Online:

[3] Koch CG et al. (2013): Hospital-acquired anemia: prevalence, outcomes, and healthcare implications. J Hosp Med. (9):506 – 512.

[4]. Hönemann C et al. (2021): Reticulocyte and Erythrocyte Hemoglobin Parameters for Iron Deficiency and Anemia Diagnostics in Patient Blood Management. A Narrative Review. J Clin Med. 10: 4250 – 4262.

[5] Hönemann C et al. (2021): Reticulocyte Haemoglobin as a Routine Parameter in Preoperative Iron Deficiency Assessment. Endocrinol Metab. 5(1): 154 – 158.

[6] Arbiol-Roca A et al. (2018): Reference intervals for a complete blood count on an automated haematology analyser Sysmex XN in healthy adults from the southern metropolitan area of Barcelona. EJIFCC. 29(1): 48 – 54. Free online:

[7] Toki Y et al. (2017): Reticulocyte hemoglobin equivalent as a potential marker for diagnosis of iron deficiency. Int J Hematol. 106(1): 116 – 125.

Copyright © Sysmex Europe SE. All rights reserved.