Measures of iron overload

Currently available measures of iron overload in clinical practice.
Diagnostic tool Characteristics Advantages Disadvantages
Calculation of transfusion iron burden Provide a direct quantitative estimate of the body iron burden Easy to calculate, inexpensive Unreliable in patients with bleeding or chelation therapy
Serum ferritin level Indirect serologic estimation of body iron burden Widely available; easy to perform; low-cost; repeatable Unreliable in patients with inflammation, liver function deficiency, and ascorbate deficiency
Serum transferrin saturation High sensitivity and specificity in untransfused patients Widely available; easy to perform; low-cost; repeatable No quantitative correlation to iron burden
SQUID Direct instrumental estimation of hepatic iron concentration Noninvasive, repeatable Expensive; not widely available; not validated; significant underestimation; not applicable to the heart
MRI R2 Indirect instrumental estimation of tissue iron concentration Noninvasive, repeatable; validated in the liver Expensive; not widely available; reliable up to LIC of 15mg/gDW; not applicable for cardiac assessment
MRI T2* Indirect instrumental estimation of tissue iron concentration Noninvasive; repeatable; validated in the heart; provides cardiac functional information Expensive; not widely available; complex, requires skilled radiologist
Liver biopsy Provides a direct estimation of iron overload Validated and quantitative method to estimate hepatic iron concentration (gold standard) Invasive (cannot be employed in many patients with hematologic malignancies)
Non-transferrin bound iron (NTBI)1 Research tool at present Noninvasive method; estimates generation of the toxic iron fraction Not validated and not widely available. Not currently useful in clinical practice
Serum hepcidin level Research tool at present Noninvasive method that identifies patients at high risk of iron loading Not widely available. Not currently useful in clinical practice