The following data refer to a 48-year-old female admitted electively to ICU following extensive pelvic surgery for invasive endometrial carcinoma. The patient has remained in ICU for 22 days because of complications including acute kidney injury.
|Parameter||Patient Value||Normal Adult Range|
|Haemoglobin||66 g/L*||125 – 180|
|Serum ferritin||14 μg/L*||15 – 300|
|Serum iron||3 μmol/L*||9 – 27|
|Total Iron Binding Capacity (TIBC)||86 μmol/L*||47 – 70|
|Transferrin Saturation||9%*||16 – 40|
|Erythropoietin level||41 U/L*||4 – 28|
|C-reactive protein (CRP)||60 mg/L*||<8|
a) What abnormality is demonstrated in this patient? Give your reasoning. (20% marks)
b) Give two potential causative factors in this patient. (10% marks)
c) Briefly outline the available treatment options to correct the demonstrated abnormality including any disadvantages / risks. (20% marks)
Iron deficiency anaemia as evidenced by:
- decreased haemoglobin
- decreased iron
- decreased ferritin
- increased erythropoietin
- increased TIBC.
Pre-existing dietary deficiency
IV iron replacement – no demonstrated benefit and risks of adverse effects (awaiting Ironman study)
Oral iron replacement
Erythropoeitin – expensive and no demonstrated benefit
Blood transfusion – risks of transfusion including immunosuppression
Nil – may have reduced oxygen carrying capacity for some time until correction of Hb
Local resources to help with such questions include the following chapters:
- Morphological abnormalities of red blood cells
- Interpretation of iron studies
- Anaemia in critical care
In the above, there is a table of typical findings which is reproduced below:
|Iron deficiency anaemia||low||low||low||low||high||<20%||high|
|Anaemia of chronic disease||low||low||low||normal||low||normal||low or normal|
|Acute phase response||normal||normal||low||high||low||low||low|
Following from this, the results in this SAQ are pretty clearly iron deficiency anaemia (low haemoglobin, low iron, high TIBC, etc). The erythropoietin level is appropriately elevated, but not essential to making the diagnosis. Apart from blood loss and dietary deficiency, there's not much that can be added to the "potential causative factors".
The available treatment options are:
- Iron supplementation
- Blood transfusion
The college also included "do nothing" as a management option, though one might object that conceptually this would be the very opposite of a management plan. They also included recombinant human EPO as one of the treatment options, but then they also gave us a serum EPO which is significantly elevated. This defies logic- adding more exogenous EPO to the already high EPO level is unlikely to achieve a glorious haemopoietic victory, as the haemoglobin was still low even with the EPO levels almost double the upper range of normal. Moreover, giving EPO is not going to do anything to replenish your iron stores.
The most logical solution would be to give iron, or actual blood. Blood transfusion is of course the last option. The pros and cons of blood transfusion in the ICU are discussed in greater detail elsewhere. Iron replacement is probably somewhat less toxic, and seems like a sensible solution to a condition where the deficiency of iron is the main problem. One should not be deterred from doing this, even though the IRONMAN trial did not find any improvement in the rate of blood transfusion in their iron-infused group. Those patients did end up with a significantly higher haemoglobin at discharge, even though they were not specifically selected for having iron deficiency.
The objection to the use of IV iron is based in the finding that the iron-infused group has an increased nosocomial infection rate (28.6% vs. 22.9%). Apart from this, there was no major difference in the adverse event rate between the two groups. In any case, you don't have to give the iron intravenously. Oral iron replacement is not without its charm, and only slightly less effective (Bonovas et al, 2016).
Hawkins, Stephen F., and Quentin A. Hill. "Diagnostic Approach to Anaemia in Critical Care." Haematology in Critical Care: A Practical Handbook (2014): 1-8.
Pieracci, Fredric M., et al. "A Multicenter, Randomized Clinical Trial of IV Iron Supplementation for Anemia of Traumatic Critical Illness*." Critical care medicine 42.9 (2014): 2048-2057.
Litton, Edward, et al. "The IRONMAN trial: a protocol for a multicentre randomised placebo-controlled trial of intravenous iron in intensive care unit patients with anaemia." Crit Care Resusc 16 (2014): 285-290.
Corwin, Howard L., et al. "Efficacy of recombinant human erythropoietin in critically ill patients: a randomized controlled trial." Jama 288.22 (2002): 2827-2835.
Mesgarpour, Bita, et al. "Safety of off-label erythropoiesis stimulating agents in critically ill patients: a meta-analysis." Intensive care medicine 39.11 (2013): 1896-1908.
Litton, Edward, et al. "Intravenous iron or placebo for anaemia in intensive care: the IRONMAN multicentre randomized blinded trial." Intensive care medicine 42.11 (2016): 1715-1722.
Bonovas, Stefanos, et al. "Intravenous versus oral iron for the treatment of anemia in inflammatory bowel disease: a systematic review and meta-analysis of randomized controlled trials." Medicine 95.2 (2016).