Investigations

^{Cobalamin deficiency}

• intrinsic factor antibodies ^c
• Schilling test ^c  

Why?

Intrinsic factor antibodies and an abnormal Schilling test make cobalamin deficiency more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
low-serum cobalamin c (pre-test probability: 58%)	cobalamin deficiency (response to cobalamin)	anti-intrinsic factor antibodies	2.6 (1.5 to 4.7)	79%	0.63 (0.49 to 0.80)	48%
		abnormal Schilling test	2.5 (1.6 to 3.8)	70%	0.21 (0.089 to 0.48)	16%