Description

A storage deficiency in the reticulo-endothelial system (RES) can be detected at a very early stage. Clinically, a threshold value of 20 ng/mL has proved useful in the detection of prelatent iron deficiency. This value provides a reliable indication of exhaustion of the iron reserves that can be mobilized for hemoglobin synthesis. Latent iron deficiency is defined as a fall below the 12 ng/mL ferritin threshold. These two values necessitate no further laboratory elucidation, even when the blood picture is still morphologically normal. If the depressed ferritin level is accompanied by hypochromic, microcytal anemia, then manifest iron deficiency is present. When the ferritin level is elevated and the possibility of a distribution disorder can be ruled out, this is a manifestation of iron overloading in the body. 400 ng/mL ferritin is used as the threshold value. Elevated ferritin values are also encountered with the following tumors: acute leukemia, Hodgkin’s disease and carcinoma of the lung, colon, liver and prostate. The determination of ferritin has proved tobe of value in liver metastasis. Studies indicate that 76% of all patients with liver metastasis have ferritin values above 400 ng/mL. Reasons for the elevated values could be cell necrosis, blocked erythropoiesis or increased synthesis in tumor tissue.
LIMITATION: In patients receiving therapy with high biotin doses (i.e. > 5 mg/day), no sample should be taken until at least 8 hours after the last biotin administration