Reticulocyte haemoglobin equivalent (RET-He)
What is RET-He parameter?
RET-He is a haematology parameter which reflects the haemoglobin content of reticulocytes – immature red blood cells. Determining the number or concentration of reticulocytes (RET) provides timely information about the "quantity" of erythropoiesis in the bone marrow. On the other hand, determination of the haemoglobin content of reticulocytes (RET-He) reflects the haemoglobinisation of reticulocytes and thus gives an indication of the "quality" of erythropoiesis. The parameter is readily available from a routine laboratory analysis of an EDTA blood sample.
How is RET-He measured?
Reticulocytes or immature red blood cells are newly released from the bone marrow, reflecting is erythropoietic activity, and their high RNA content is measured using a specific fluorescence method. RET-He is a diagnostic parameter obtained from Sysmex’s haematology analysers equipped with a RET channel. In the RET channel, all reticulocytes are stained with a fluorescent dye and counted. The population in the area of high fluorescence intensity is separated as reticulocytes and the RET-He parameter is derived from the mean forward scatter light of reticulocyte population.
Reference ranges (adults)
RET-He: 29.3 - 35.4 pg (1.82 - 2.20 fmol) [1]
Statement
CBC and RET-He results can help identify patients with iron deficiency anaemia, determine the need for and response to intravenous iron, and reduce the time to therapeutic decisions. (Auerbach M et al. 2021)
Benefits
Various clinical benefits in the diagnosis and treatment of anaemia and iron deficiency were documented in the literature for the RET-He parameter:
- RET-He reflects the bioavailability of iron for erythropoiesis in a similar way to transferrin saturation [1-2] and is not affected by the acute-phase reaction [3-4].
- It has been reported to have high accuracy, sensitivity and specificity for identifying iron deficiency [5-6].
- Supports accurate identification of iron deficiency, including functional iron deficiency, at an early stage [1,7].
- Serves as an early indicator of the response to iron therapy and/or erythropoietin stimulating agents within 2–4 days [8-9].
- RET-He supports detection of subclinical iron deficiency – the lack of iron before the onset of anaemia [10-11].
- Helps to manage patients with postoperative anaemia or anaemia in chronic kidney disease [2,12].
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References
[1] Hoenemann 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(18): 4250.
[2] Muñoz M et al. (2017): International consensus statement on the peri-operative management of anaemia and iron deficiency. Anaesthesia. 72(2): 233–247.
[3] Thomas L et al. (2005): Reticulocyte hemoglobin measurement-comparison of two methods in the diagnosis of iron-restricted erythropoiesis. Clin Chem Lab Med. 43(11): 1193–202.
[4] Thomas C et al. (2002): Biochemical markers and hematologic indices in the diagnosis of functional iron deficiency. Clin Chem. 48(7): 1066–76.
[5] Buttarello M et al. (2016): Evaluation of the hypochromic erythrocyte and reticulocyte hemoglobin content provided by the Sysmex XE-5000 analyzer in diagnosis of iron deficiency erythropoiesis. Clin Chem Lab Med. 54(12): 1939–1945.
[6] Mehta S et al. (2016): Reticulocyte Hemoglobin vis-a-vis Serum Ferritin as a Marker of Bone Marrow Iron Store in Iron Deficiency Anemia. J Assoc Physicians India. 64(11): 38–42.
[7] Hoenemann C et al. (2021): Reticulocyte Haemoglobin as a Routine Parameter in Preoperative Iron Deficiency Assessment. Endocrinol Metab Vol. 5 No.1: 154.
[8] Almashjary MN et al. (2022): Reticulocyte Hemoglobin-Equivalent Potentially Detects, Diagnoses and Discriminates between Stages of Iron Deficiency with High Sensitivity and Specificity. J Clin Med. 11(19): 5675.
[9] Auerbach M et al. (2021): Using Reticulocyte Hemoglobin Equivalent as a Marker for Iron Deficiency and Responsiveness to Iron Therapy. Mayo Clin Proc. 96(6): 1510–1519.
[10] Toki Y et al. (2017): Reticulocyte hemoglobin equivalent as a potential marker for diagnosis of iron deficiency. I Int J Hematol. 106(1): 116–125.
[11] Tiwari AK et al. (2018): Applying newer parameter Ret-He (reticulocyte haemoglobin equivalent) to assess latent iron deficiency (LID) in blood donors-study at a tertiary care hospital in India. Vox Sang. 113(7): 639–646.
[12] Shander A et al. (2023): Recommendations from the International Consensus Conference on Anemia Management in Surgical Patients (ICCAMS). Ann Surg. 277(4): 581–590.
