TSH And The Menstrual Cycle

A new paper showing an influence of the menstrual cycle on TSH levels in women on T4. It is easily downloadable. The abstract is below.

Front. Endocrinol., 29 September 2017 | doi.org/10.3389/fendo.2017....

Serum Thyrotropin and Phase of the Menstrual Cycle

Salvatore Benvenga, Flavia Di Bari, Roberta Granese and Alessandro Antonelli6

Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy

Master Program on Childhood, Adolescent and Women’s Endocrine Health, University of Messina, Messina, Italy

Interdepartmental Program of Molecular & Clinical Endocrinology, and Women’s Endocrine Health, Azienda Ospedaliera Universitaria Policlinico “G. Martino”, Messina, Italy

Department of Human Pathology, University of Messina, Messina, Italy

Division of Obstetrics and Gynecology, University of Messina, Messina, Italy

Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy

Abstract

About one-fifth of patients treated with levothyroxine have serum thyrotropin (TSH) above target concentrations but, in approximately 15% of them, the cause of this TSH insufficient normalization remains unknown. We report the cases of two regularly menstruating women with known thyroid disease who had TSH levels consistently >3 mU/L (and sometimes above target levels) during mid-cycle, but consistently lower serum levels during the follicular and luteal phases of menstrual cycle. A major TSH release by the thyrotrophs in response to high circulating levels of estradiol (E2) at mid-cycle may increase levels of TSH compared to other phases of the cycle. The increased TSH can be misinterpreted as refractory hypothyroidism if the woman is under L-T4 replacement therapy or as subclinical hypothyroidism if the woman is not. Our findings might have important implications for diagnosis and management of thyroid disease, suggesting to request serum TSH measurements outside of the periovulatory days.

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Thank you for sharing this. I have a particular interest in LH/FSH (because I have so little of either!). I can see that it was measured for patient A, but cannot tell if it was thought to be relevant, or just to confirm different stages of the woman's menstrual cycle.

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Thanks for sharing. I have felt that estrogen and progesterone play quite a part in how well T4 therapy works depending on where you are in your monthly cycle. I have low estrogen and low progesterone and hashimotos and wonder what the research and sampling might show with this combination?

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Thanks for posting Diogenes. It is good that they have discovered the variations due to menstrual cycle.

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