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Oral combined contraceptives did not seem to alter histamine metabolism in females. During treatment with gonadotrophic hormones in four amenorrhoeic patients there was a tendency towards increasing excretion of methylhistamine (MeHi) followed by a sudden decrease corresponding to changes in the urinary estrogen. the excretion of methylimidazoleacetic acid (MeImAA) seemed to parallel that of MeHi. the findings support the hypothesis that an endogenous surge of estrogen may influence histamine turnover in women. Women of postmenopausal age have about the same histamine metabolism as younger menstruating women. Estrogen medication relieved symptoms of hot flushes or sweats but did not seem to affect the histamine turnover.

The urinary excretion of histamine and its metabolites methylhistamine (MeHi) and methylimidazoleacetic acid (MeImAA) was measured during the menstrual cycle in nine healthy women, one allergic woman and three non-pregnant women with anovulatory regular cycles. Simultaneous urinary analyses of luteinizing hormone (LH) and total estrogens were performed. The healthy women showed individual variations in the excretion of histamine, MeHi and MeImAA. This observation has been interpreted as an expression of minor individual differences in the catabolism of histamine. At midcycle an increase in the urinary excretion of histamine metabolites was sometimes evident and a statistically significant correlation could be established between MeHi and estrogen in urine. These results may support previous findings of histamine release by estrogens in uterine tissue but may also reflect an elevated histamine formation. The allergic woman excreted constantly increased amounts of histamine and its metabolites, especially when her allergic symptoms became aggravated pre-menstrually. She did not exhibit any change in MeImAA excretion at midcycle but the MeHi-excretion varied with the excretion of estrogens in the urine. The subjects with anovulatory menstrual cycles had low values of histamine and metabolites although within the normal variations.

Determination of the urinary excretion of histamine and methylhistamine was performed in intact and gonadectomized male and female guinea-pigs. The excretion of methylhistamine varied more than that of histamine both in the same animal and between different animals. The urinary excretion of histamine and methylhistamine reflects fairly well the total histamine turnover in the animal, provided that aminoguanidine is administered to inhibit diamine oxidase activity. There was no sex difference in the excretion of histamine and methylhistamine and gonadectomy did not influence the urinary output. Female sex steroids had little ifany effect upon histamine turnover in the guinea-pig which is in contrast to the situation in rats and mice.