The measurement of haemoglobin content of reticulocytes (RET-He, reticulocyte haemoglobin equivalent) is an inexpensive parameter for the diagnosis and monitoring of iron supply to erythropoiesis. With the reticulocyte count giving a direct indication of the current quantity of erythropoiesis, the haemoglobin content of the reticulocytes measures iron supply to erythropoiesis and thus the quality of the cells. Changes in iron status of erythropoiesis can thus be detected in a much timelier fashion. In many hospitals, this method is already available, but underappreciated and used. A differentiated anemia diagnosis via other means, example, via ferritin, transferrin saturation, iron etc. necessarily increases laboratory costs. In the first pillar of Patient Blood Management, the preoperative anemia diagnosis, measuring RET-He could thus be a valuable option, since the costs of measurement are around 0.70€-1.00€. In contrast, costs are much higher for the traditional parameters ferritin (17.76€ as per German private healthcare system) and transferrin saturation (6.71€). More studies are urgently indicated to further analyze the role RET-He can play in Patient Blood Management.