<p><strong>INTRODUCTION: </strong>Thyroid lobectomy reduces risks of surgical complications and need for levothyroxine (LT4). We aimed to identify the clinical course and risk factors for post-lobectomy hypothyroidism to optimize surgical counseling and management in pediatric patients undergoing lobectomy.</p>

<p><strong>METHODS: </strong>Clinical and biochemical presentations pre- and post-lobectomy were retrospectively reviewed for 110 patients who underwent thyroid lobectomy between 2008 and 2020 at the Children's Hospital of Philadelphia.</p>

<p><strong>RESULTS: </strong>Approximately 28.2% of patients (31/110) developed post-lobectomy hypothyroidism defined by an elevated thyroid stimulating hormone (TSH) level, including 24.5% (27/110) with subclinical hypothyroidism (TSH &gt; 4.5 and &lt; 10.0 mIU/L) and 3.6% (4/110) with overt hypothyroidism (TSH &gt; 10.0 mIU/L). LT4 was initiated in 12.7% (14/110) of cases. Most patients (81.6%; 84/103) recovered euthyroidism within 12 months post-lobectomy. When excluding patients with autonomous nodule(s), median preoperative TSH was 1.09 (IQR = 0.70-1.77) mIU/L and 1.80 (IQR = 1.02-2.68) mIU/L in euthyroid and hypothyroid patients, respectively, with multivariate logistic regression confirming the association between an increased preoperative TSH and post-lobectomy hypothyroidism (OR = 1.8; 95% CI = 1.08-3.13; p = 0.024). Of the patients who underwent thyroid lobectomy and developed post-operative hypothyroidism (n = 31), 38.7% (12/31) had a pre-operative diagnosis of an autonomous thyroid nodule.</p>

<p><strong>CONCLUSIONS: </strong>Thyroid function should be evaluated post-lobectomy to assess the need for LT4. LT4 should be considered if the TSH remains elevated, especially if an upward trend is observed or TSH is &gt; 10.0 mIU/L. Suppressed preoperative TSH associated with autonomous nodule(s) is an independent risk factor for post-lobectomy hypothyroidism.</p>