Dysfunction of the liver affects the sense of smell

Cirrhosis of the liver (CL) has been reported to be accompanied by olfactory loss. The aim of the present study was to re-investigate previous work with a special focus on differential olfactory function, the relation between CL etiology and olfactory function, and the correlations between laboratory/psychological parameters and olfactory function.

A total of 45 CL patients participated. Olfactory function was tested using the "Sniffin' Sticks" technique, which provides measures for butanol odor thresholds, odor discrimination and odor identification. Serum levels of zinc and bilirubin were obtained. Psychometric measurements included the trailmaking test.

The study provided the following major results: (1) Olfactory function was compromised in 76% of CL patients; in addition, the patient's ability to identify odors, but not odor thresholds or odor discrimination, was related to the degree of CL. This pattern may be an expression of a stronger effect of CL on the central- nervous processing of odors than on the periphery of the system. (2) Neither etiology of the CL (e.g., alcoholism) nor serum levels of bilirubin and zinc were correlated with olfactory function. However, (3) there was a relation between the results from psychometric function tests and the ability to identify odors.

Although the reason for olfactory dysfunction in CL is far from clear, future investigations should focus on the hypothesis that endogenous intoxication may lead to a stronger deficit in the central-nervous processing of olfactory information than to peripheral lesions in the olfactory system. In addition, while more specific research is needed, olfactory dysfunction may serve as a subclinical indicator of hepatic encephalopathy.