Pernicious Anemia: Sensitivity and Specificity

Introduction: Autoimmune attack of the parietal cells in the stomach that are responsible for producing intrinsic factor. Intrinsic factor is necessary for the absorption of vitamin B12 (cobalamin), thus its loss causes Megaloblastic Anemia.

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Tags: Autoimmune Hematologic Tag this Diagnosis.

The sensitivity and specificity of findings for Pernicious Anemia 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.)

Sensitive and Specific Findings
Finding	Result	Sensitivity	Specificity
[ + ] Anti-parietal Cell Antibody	+ 0 -	85%	90%
Study: Arch Intern Med. 1999 Jun 28;159(12):1289-98. PMID: 10386505

Sensitive Findings
Finding	Result	Sensitivity	Specificity
[ + ] Elevated Fasting Serum Gastrin		Sensitivity = 90%
>200ng/L. Specificity not assessed. Study: Arch Intern Med. 1999 Jun 28;159(12):1289-98. PMID: 10386505 Am J Clin Pathol. 1988 Oct;90(4):442-5. PMID: 3177265

Poorly Diagnostic Findings
Finding	Result	Sensitivity	Specificity
[ + ] Anti-Intrinsic Factor Antibodies		Sensitivity = 50%
Specificity not mentioned but given as "rarely present in healthy individuals". Some people with Graves + anti-IF may progress to pernicious anemia. Study: Arch Intern Med. 1999 Jun 28;159(12):1289-98. PMID: 10386505