Israel Medical Association Journal

Background: Previous surveys demonstrated variations in the clinical practices relating to the treatment and screening of maternal thyroid dysfunction.

Objectives: To study the current practices in the management of subclinical hypothyroidism (SCH) and thyroid nodules during pregnancy of obstetricians/gynecologists (OB/GYNs) and endocrinologists in Israel.

Methods: An electronic questionnaire was sent by email to all members of the Israeli Endocrine Society and the Israel Society of Obstetrics and Gynecology. Questionnaires included demographic data and clinical scenarios with questions regarding the screening and management of pregnant women with SCH, hypothyroxinemia, and a palpable thyroid nodule. The questionnaire for OB/GYNs was slightly modified.

Results: We received 90 responses from endocrinologists and 42 responses from OB/GYNs. Among endocrinologists, 39% would repeat a thyroid-stimulating hormone (TSH) test of 2.9 mU/L with normal free thyroxine and treat with thyroxine if the second result was above 2.5 mU/L. Among OB/GYNs, 73% would manage a woman with SCH at the beginning of her pregnancy by themselves and only 22% would start thyroxine after a first TSH result above 2.5 mU/L. Concerning screening, 57% endocrinologists and 71% OB/GYNs recommended screening for thyroid dysfunction in every woman at the beginning of her pregnancy. Among endocrinologists, 54% would order an ultrasound for a palpable thyroid nodule and perform a fine needle aspiration only for suspicious lesions.

Conclusions: The medical approach to thyroid disease in pregnant women remains a matter of controversy. Our results support the need for larger and prospective clinical studies.

Background: Heart rate variability is a sensitive marker of cardiac sympathetic activity.

Objectives: To determine whether long-term hyperthyroidism induced by thyroxine suppressive therapy affects HRV[1].

Methods: Nineteen patients treated with suppressive doses of thyroxin for thyroid cancer and 19 age-matched controls were enrolled. Thyroid function tests and 1 minute HRV were performed on all subjects and the results were compared between the groups. The 1 minute HRV was analyzed during deep breathing and defined as the difference in beats/minute between the shortest and the longest heart rate interval measured by eletrocardiographic recording during six cycles of deep breathing.

Results:  One minute HRV during deep breathing was significantly lower among thyroxine-treated patients compared to healthy controls (25.6 ± 10.5 vs. 34.3 ± 12.6 beats/min, P < 0.05). There were no significant differences in mean, maximal and minimal heart rate between the groups

Conclusions: Thyroxine therapy administered for epithelial thyroid cancer resulted in subclinical hyperthyroidism and significantly decreased HRV due to autonomic dysfunction rather than basic elevated heart rate.