Circadian variation of serum prolactin and TSH of women in health or with mammary carcinoma, fibroadenoma or fibrocystic mastopathy.

Prolactin and TSH were determined in serum samples obtained at 4-hourly intervals throughout a 24-hour span from healthy women and from women with fibrocystic mastopathy, fibroadenoma or carcinoma of the breast. Data were subjected to analysis by the population mean-cosinor method. Differences in circadian mesor of prolactin among the 4 groups were statistically significant (P < .01), with healthy women having the lowest value. Prolactin amplitude differences among the groups were of borderline statistical significance (P = .05), while no differences in circadian acrophase were apparent. No statistically significance differences in TSH circadian mesor, amplitude or acrophase could be demonstrated. Individual values from subjects with breast disease were compared with time-qualified tolerance intervals based on data from healthy subjects. If these results can be corroborated on larger populations, sampling about 3 hours after arising may best detect an abnormal serum prolactin elevation. Results from this and other studies indicate the need for multi-variable and multifrequency investigations of breast disease.