Postintervention Serum TSH Levels May Be Useful to Differentiate Patients Who Should Undergo Levothyroxine Suppressive Therapy After Thyroid Surgery for Multinodular Goiter in a Region with Moderate Iodine Deficiency

Recent studies have raised doubts about the efficacy of the postoperative use of levothyroxine (LT₄) suppressive doses in patients who underwent thyroid surgery for multinodular goiter. The purpose of this retrospective study was to examine the efficacy of different doses of LT₄ in preventing postsurgical recurrences of simple multinodular goiter and to identify a marker that could be useful in discriminating patients with a higher risk of developing recurrence. Two hundred thirty-two patients (57 male, 175 female) operated for nontoxic multinodular goiter were divided into two groups: (I) patients with normal postsurgery thyrotropin (TSH) levels (0.25 to 4.5 mU/L) and (II) patients with elevated postsurgery TSH levels (>4.5 mU/L). All patients were subjected to replacement (1.3 μg LT₄/kg/day) or suppressive (1.7 μg LT₄/kg/day) doses of LT₄, and they were followed for a median period of 6 years (range 2 to 12). No statistical difference was found for sex, age, and postsurgery serum TSH between patients submitted to suppressive and replacement therapy. The ultrasound (US) detection of new postsurgery nodules of at least 0.5 cm maximum diameter was considered a recurrence of disease and was found in 10% of the cases studied. Patients with normal postsurgery serum TSH showed a high recurrence rate (30.4%) when submitted to lower daily doses of LT₄. In patients with elevated postsurgery serum TSH, the rate of nodular goiter recurrence did not vary with different types of LT₄ therapy. In conclusion, our results suggest that the postsurgical serum TSH is useful for prediction of nodular goiter recurrence, as it reflects the amount of residual functioning thyroid tissue in the cervical area. It may also be indicative of patients who might benefit from LT₄ suppressive therapy.