Thalassemia: Likelihood Ratios

Introduction: Thalassemia is in the differential diagnosis of a microcytic anemia. The two other categories of microcytic anemia are Iron Deficiency Anemia and Anemia of Chronic Disease. There are a number of different 'indices' that one can use to distinguish IDA from thalassemia (see below), but iron studies / ferritin are probably more accurate.

I have chosen to simply paste in references here because the numbers are rather discordant among the studies.

J Trop Pediatr. 2007 Apr;53(2):93-7. PMID: 17166936

J Int Med Res. 2009 Jan-Feb;37(1):25-30. PMID: 19215670

Pediatr Int. 2002 Dec;44(6):612-6. PMID: 12421257

Ann Hematol. 2007 Jul;86(7):487-91. PMID: 17476506

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Differential Diagnoses include: Iron Deficiency Anemia

The likelihood ratios of findings for Thalassemia are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] England and Fraser Index		No accuracy specified.
Study: no study specified.
[ + ] Shine and Lal Index		No accuracy specified.
Study: no study specified.
[ + ] RDW, decreased		No accuracy specified.
in thalassemia, the RDW tends to be normal to decreased (whereas it tends to be increased in iron deficiency) Study: no study specified.
[ + ] Mentzer index		No accuracy specified.
Study: no study specified.
[ + ] Srivastava Index		No accuracy specified.
Study: no study specified.
[ + ] Green and King Index		No accuracy specified.
Study: no study specified.