Vitamin B12 deficiency and the dexamethasone suppression test

The authors describe dexamethasone nonsuppression in a depressed patient with a vitamin B12 deficiency. After B12 replacement there was no change in the patient's clinical state. However, the dexamethasone suppression test normalized. Thus, dexamethasone nonsuppression in this patient seemed to be more closely related to vitamin B12 deficiency than to affective state.