Vitamin B12 excretion in patients with various skin diseases.

The excretion in the urine of (58)Co after an oral dose of (58)Co vitamin B(12) given together with intrinsic factor has been found to be reduced in a number of patients with psoriasis, eczema, and other less common dermatoses. There is a correlation between the abnormality and the extent of the rash. A reduced glomerular filtration rate was found in a few of the patients in whom it was measured, and this must have been responsible, at least in part, for the reduced excretion of vitamin B(12) in these patients, but abnormal vitamin B(12) excretion also occurred in the absence of impaired renal function. Our evidence is insufficient to show whether malabsorption or increased tissue utilization of vitamin B(12) was the explanation in other cases. Certainly a number of patients had steatorrhoea, and in these it is most likely that malabsorption was the major factor. In patients without steatorrhoea a lone malabsorption of vitamin B(12) cannot be excluded. A decreased serum concentration of vitamin B(12) was found in only one of the patients.