Quick (1931) first reported on the conjugation of benzoic acid in man and recorded the hippuric acid excretion rate as a test for liver function. Quastel and Wales (1938) found faulty detoxication in catatonic schizophrenic patients and later (1940) a return to normal values after clinical remission. A number of other workers, particularly Georgi, Fischer, Weber and Weiss (1948–49) described this disturbed benzoic acid detoxication as a general syndrome in all schizophrenics. When giving glycine simultaneously with the benzoic acid they noticed a normalized and increased hippuric acid excretion rate in patients who originally showed decreased hippuric acid excretion. The Quick test, modified in this way, was used in order to prove that the decreased hippuric acid excretion rate is not the expression of a disturbance in the coupling mechanism between benzoic acid and glycine but rather a disturbed ability of the organism to mobilize glycine. Mall and Jünemann (1952) have lately confirmed the results of Georgi et al. in extensive investigations. They reached the conclusion that variations in the hippuric acid excretion rate are mainly due to a disturbance of the ability to dispose of glycine in the schizophrenic organism. They confirmed previous results of Georgi according to whom treatment of the patients, which was carried out partly from the point of view of disturbed liver function only, partly combined with insulin and electroshock, leads to improvement of the detoxication rate. Persky, Gamm, and Grinker (1952) have also recently seen decreased hippuric acid excretion values in catatonic schizophrenic subjects, and have reported a return of the hippuric acid excretion to normal after successful psychiatric treatment. In their series patients who manifested free anxiety symptoms, excreted elevated amounts of hippuric acid; the excretion rate returning to normal levels after successful psychiatric treatment.
Urinary hippuric acid excretion as related to changes in cell wall digestibility due to variation in degradable protein supply
