Section of Medicine 43in explanation. Very high concentrations of 5-HT are known to release the bound histamine of the tissues but whether the concentrations reached in man are sufficient to do this is by no means certain. Their second suggestion is that possibly the same decarboxylase which converts 5-hydroxytryptophan into 5-HT may also convert the amino acid histidine into histamine and that the presumed high concentration of this enzyme in carcinoid tissue may lead to a large production of histamine. This is a matter which can be settled experimentally. In any case it seems that not all patients with malignant carcinoid excrete abnormal amounts of histamine, for of 2 cases I have personally investigated one did and the other did not. The reason for this difference and what effect the presence of large amounts of histamine may have on the symptomatology remains to be determined. Treatment.-There is, of course, very little that can be done as there are invariably liver secondaries present. Surgical removal of malignant glands has been reported to have been followed by some amelioration of symptoms but surgery carries a definite risk. A severe attack may be precipitated by handling or pressing on malignant tissue and I know of 2 cases in which an attack, ultimately leading to the death of the patient, developed at an early stage in the operation before there was any manipulation of the growth. Temporary improvement has been twice reported after 198Au and deterioration twice after radiotherapy.Potent antagonists to 5-HT are known but so far they have not shown themselves to be of niuch value in treating these cases. Bromlysergic acid diethylamide, chlorpromazine and dibenyline would appear to be the most promising for a trial. In view of the precipitation of attacks by excitement and by noradrenaline, the use of adrenaline in treating bronchospasm would seem inadvisable. Finally in cases where large amounts of histamine are excreted it is possible that some amelioration of symptoms might be obtained from antihistamine drugs.
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