An augmented Schilling test in the diagnosis of pernicious anaemia.

A patient with otherwise typical addisonian pernicious anaemia and serum anti-intrinsic-factor antibody failed to respond to oral intrinsic factor on repeated testing during three years of therapy with parenteral vitamin B 12. There was no evidence of generalised malaborption. To test the hypothesis that binding of intrinsic factor to gut secretory antibody was responsible, an "augmented" Schilling test was devised using eight times the usual dose of intrinsic factor. This increased dose of intrinsic factor resulted in normal absorption of the test dose of vitamin B 12 confirming the diagnosis. It is suggested that the augmented Schilling test may be useful in the diagnosis of the occasional patient with features of pernicious anaemia who fails to respond to conventional doses of intrinsic factor in the Schilling test.