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Thyroid Biology and Disease

MON-347 - The Regenerative Potential of the Thyroid Gland to Maintain Euthyroid State after Total Thyroidectomy

Monday, June 15, 2026
9:00 AM - 2:00 PM CT
Location: ENDOExpo; Poster Floor

    Abstract Poster Presenter(s)

  • TM

    Tochukwu A. Madu, MD

    Los Angeles General Medical Center
    Los Angeles, California, United States

    • Co-Author(s)

  • AK

    Ashley Kwon, MD (she/her/hers)

    Resident Physician
    USC/Los Angeles General Medical Center
    Los Angeles, CA, United States

    • Senior Author/Primary Investigator(s)

  • CN

    Caroline T. Nguyen, MD

    USC Keck School of Medicine
    Los Angeles, California, United States

Disclosure(s):
Ashley Kwon, MD: No financial relationships to disclose
Background

This case highlights the gaps in our understanding of the factors governing the thyroid’s capacity to regenerate and produce thyroid hormone.

Clinical Case

A 30-year-old woman underwent a total thyroidectomy at age 14 for a left thyroid mass. FNA cytology revealed sheets and small clusters of follicular cells with macro- and microfollicular morphology, concerning for malignancy. The patient underwent a total thyroidectomy.  The thyroid gland weighed 60 grams, with the left and right lobes measuring 6.0 x 5.1 x 4.0 cm and 3.2 x 2.9 x 0.9 cm, respectively. Pathology demonstrated a completely encapsulated follicular adenoma measuring 5.8 x 4.5 x 4.0 cm.

The patient was started on levothyroxine (LT4) after surgery and remained on therapy for two years before self-discontinuing due to tremors and fatigue. During her first pregnancy at age 16, LT4 175 mcg was restarted and again discontinued postpartum. At age 23, LT4 150 mcg was initiated during her second pregnancy and increased to 175 mcg for a TSH 5.99 mIU/L then self-discontinued.

The patient re-presented to the emergency department complaining of fatigue. Paradoxically, the patient was biochemically euthyroid off LT4 with TSH 2.06 mIU/L. Ultrasound revealed left-sided mildly heterogeneous and hypervascular regenerative thyroid tissue measuring 3.9 × 1.1 × 1.9 cm. During her third pregnancy at age 30, she has remained biochemically euthyroid throughout pregnancy.

Discussion

This case demonstrates the thyroid’s capacity to regenerate functional tissue after total thyroidectomy and to meet increased hormone demands during pregnancy. While one prior report describes thyroid tissue regrowth, this is the first to document regenerated tissue sufficient for pregnancy-related demands. The mechanisms of thyroid regrowth remain poorly understood, and studies are largely confined to animal models. Further investigation may inform future therapies and potentially reduce the need for lifelong thyroid hormone replacement after thyroidectomy.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*