Interpreting Lab Tests of Iron Status

Functional IDIDIDAACDIDA + ACDIRIDA
Hbnormalnormallowlowlowlow
MCV & MCHnormalnormallowlow-Nloewv. low
Ferritin
(mcg/L)
normallow (< 30)low (< 30)N or highN (up to 100)variable
TFS
(15 – 45 %)
low-normallow-N / lowlowlow-Nlow-Nlow
Serum iron
(10 – 30 mmol/L)
low-normallowlowlowlowlow
A ferritin < 30 mcg/L in the adult = iron deficient. Ferritin 30-100 may represent ID if there is coexisting inflammatory disease; while ferritin greater than the upper limits of normal may be due to inflammatory disease, liver disease, or iron overload. Isolated reduction of iron is of dubious significance given the wide variability of serum iron concentrations.

Functional Iron Deficiency: inadequate iron supply to the bone marrow despite iron stores being present.

Iron Deficiency (ID): decreased levels of total body iron, especially iron stores, but inadequate levels of erythroid iron.

Iron Deficiency Anaemia: decreased levels of total body iron resulting in anaemia.

Anaemia of chronic disease (ACD) or inflammation: multifactorial anaemia with up-regulation of hepcidin and abnormal iron homeostasis.

Iron Refractory Iron-Deficiency Anaemia (IRIDA): an iron-deficiency anaemia unresponsive to oral iron therapy – i.e. indication for iron injection.

Treatment and Investigations of Iron Deficiency should occur concurrently:

  • history
  • physical examination
  • medications review
  • coeliac screen
  • urinalysis + MSU (1% renal tract malignancy)
  • renal function
  • faecal immunohistochemical test (colonoscopy)

Male / postmenopausal female –> GI investigations

Premenopausal female –> GI investigations for high-risk or those with persistent ID after empirical treatment.

Screen and manage preoperative patients for ID:

  • check Hb / iron / RFT / CRP if expect significant blood loss at surgery
  • optimise iron / Hb prior to surgery (patients who have blood transfusions do worse)

References

Baird-Gunning, Jonathan and Bromley, Jonathan. “Correcting iron deficiency.” Aus Prescr 39(6); Dec 2016: 193-9. http://www.nps.org.au/australianprescriber.

Pasricha, Sant-Rayn S., Flecknoe-Brown, Stephen C., Allen, Katrina J., Gibson, Peter R., McMahon, Lawrence P., Olynyk, John K., Roger, Simon D., Savoia, Helen F., Tampi, Ramdas; Thomson, Amanda R., Wood, Erica M. and Robinson, Kathryn L. “Diagnosis and management of iron deficiency anaemia: a clinical update.” MJA 193(9); Nov 1, 2010: 525-32.

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