Low serum ferritin

Low serum ferritin (SF) is a sensitive and specific indicator of low total body iron stores.

The WHO defines low ferritin as levels <15 μg/L for adults and <12 μg/L for children. (1)However, in clinical practice, when ferritin levels dip below 30 μg/L, iron deficiency (ID) can be ascertained. (2)

Ferritin is an acute-phase reactant that is increased in serum during chronic inflammation. Cut-off values for ferritin in ID are increased to 100 μg/L in states of chronic inflammation. Transferrin saturation (TSAT) levels below 20% are also diagnostic of ID. In chronic inflammatory conditions when ferritin levels are 100–300 μg/L, TSAT should be used to diagnose iron deficiency. (3)

Note - serum iron levels fluctuate throughout the day and should not be used exclusively for a diagnosis of iron deficiency (4)

Reference

1. World Health Organization . Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. WHO, 2011
2. Soppi ET. Iron deficiency without anemia – a clinical challenge. Clin Case Rep 2018;6:1082–6.
3. Cappellini MD, Comin-Colet J, de Francisco A, et al. Iron deficiency across chronic inflammatory conditions: International expert opinion on definition, diagnosis, and management. Am J Hematol 2017;92:1068–78
4. Cohen-Solal A, Leclercq C, Mebazaa A, et al. Diagnosis and treatment of iron deficiency in patients with heart failure: Expert position paper from French cardiologists. Arch Cardiovasc Dis 2014;107:563–71.