Laboratory Test Reference Guide

Send at 4^oC

28.9 - 36.3

RET-He test measures the haemoglobin content of reticulocytes. The reticulocyte haemoglobin content is also known as CHr when measured using other analysers.

Test Principle:

Employing new technologies, the reticulocyte haemoglobin content is obtained through our Sysmex XN analysers as part of the reticulocyte profile by utilising the principle of flow cytometry.

Reticulocytes are younger red cells that have been newly released from the bone marrow and swept into the blood stream. These reticulocytes will mature within two to four days in the peripheral blood. Reticulocyte haemoglobin content (Ret-He) is a direct measurement of the haemoglobinisation of the reticulocytes. Measuring the number of reticulocytes demonstrates the “quantity” of the erythropoiesis in the bone marrow, while measuring the reticulocyte haemoglobin content demonstrate the “quality” of those reticulocytes by being able to assess the current iron supply to erythropoiesis. The test enables detection of changes in iron status far earlier. Conventional biochemical markers for assessing iron status, such as serum iron, transferrin or ferritin,  can be drastically disturbed during inflammation with an acute phase response, or in the presence of many other severe diseases, that a clinical interpretation of the results is difficult or impossible. Ret-He is not affected by the acute phase response so is more reliable in these settings.

Using Ret-He:

RET-He alone gives information on the current bioavailability of iron – a low value means iron is lacking or iron is not bioavailable for erythropoiesis. It is often used together with ferritin. Since ferritin is increased during the acute phase of diseases, inflammation should be ruled out, e.g. by CRP.

• a high or normal ferritin value together with a low RET-He value can suggest functional iron deficiency

• low ferritin values together with low RET-He suggest a classic iron deficiency.

• RET-He is used for monitoring erythropoietin (EPO) and/or IV iron therapy. If the value increases it indicates the therapy is having a positive effect.

In iron deficiency anaemia, Ret-He is usually <25 pg. In anaemia of chronic disease and reduced iron stores without anaemia, Ret-He will be low-normal or slightly reduced but usually >25 pg. Ret-He has the same sensitivity as serum transferrin receptor in diagnosing iron deficiency anaemia and distinguish the latter from anaemia of chronic disease. Ret-He does not distinguish between iron deficiency anaemia and thalassaemia trait. In both cases, Ret-He is <25 pg.

Add-on test: within 24 hours after collection

Adult tube (3mL EDTA):  minimum 1 mL

Pediatric tube:  minimum 250 uL