Iron deficiency without anaemia is three times as common as iron deficiency anaemia (IDA).
Studies in women, adolescents and children have shown that iron deficiency without anaemia has a number of clinical consequences similar to IDA, including fatigue, impaired concentration and decreased work productivity.
There is a lack of research regarding the effects of iron deficiency without anaemia in men.
There is no consensus on the investigation of patients with ID without anaemia, however in these patients, the overall prevalence of underlying GI pathology, and in particular GI malignancy, is low.
The 2021 British Society of Gastroenterology guidelines state that, in the absence of other pointers, GI investigation is generally not warranted in premenopausal women.
However, the threshold for investigation of NAID should however be low in men, postmenopausal women, and those with GI symptoms or a family history of GI pathology.
Spectrum of iron deficiency
Absolute iron deficiency results from extensive negative iron balance, culminating in decreased or exhausted iron stores. Sequential stages are normal iron status to iron depletion (depletion of storage iron) to iron deficient erythropoiesis (red cell production affected but haemoglobin still within normal level), and finally, iron deficiency anaemia.