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

Adult Normal 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 (Iron / TIBC x 100)

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)

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College answer

  1. a)

    Iron deficiency anaemia as evidenced by:

    • decreased haemoglobin
    • decreased iron
    • decreased ferritin
    • increased erythropoietin
    • increased TIBC.

    b)

    Blood loss

    Pre-existing dietary deficiency

    c)

    IV iron replacement – no demonstrated benefit and risks of adverse effects (infection risk- IRONMAN)

    Oral iron replacement?

    Erythropoeitin – expensive and no demonstrated benefit

    Blood transfusion – risks of transfusion including immunosuppression?

    No treatment – may have reduced oxygen carrying capacity for some time until correction of Hb

Discussion

This question is essentially identical to Question 18.2 from the first paper of 2015, except in 2015 the results of the IRONMAN study were not yet available. Apart from including a mention of this 2016 trial by Litton et al, the college examiners made the curious choice of taking management recommendations from the 2015 version of the question and rewording them in the form of questions ("Oral iron replacement?").

Anyway. Local resources to help with such questions include the following chapters:

In the above, there is a table of typical findings which is reproduced below:

Interpretation of Abnormal Iron Studies
Condition MCV MCHC Serum iron Ferritin Transferrin Transferrin
saturation
TIBC
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
Iron overload normal normal high high normal high high

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).

References