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Surgical removal of one thyroid lobe may result in hypothyroidism
The background of the study. Patients with a solitary
thyroid nodule are often treated by removal the thyroid lobe that
contains the nodule (lobectomy), which should not result in hypothyroidism
if the remaining lobe is normal. In this study, thyroid function
was determined in patients who had undergone thyroid lobectomy,
and the results were correlated with the extent of infiltration
of the thyroid lobe that was removed by lymphocytes, as an indication
of autoimmune thyroid disease.
How the study was done. The study subjects were 66 patients who underwent thyroid lobectomy for a benign thyroid nodule. All had normal serum thyrotropin (TSH) concentrations before surgery. Serum TSH was measured within three months after surgery in 46 patients (70 percent) and later in 20 (30 percent). Patients with no symptoms of hypothyroidism were considered to have biochemical hypothyroidism, and those with symptoms were considered to have clinical hypothyroidism. The microscopic sections of each patient’s thyroid tissue were reviewed by a pathologist, who graded the extent of lymphocytic infiltration from 0 (none) to 4+ (severe).
The results of the study. Twelve patients (18 percent) had hypothyroidism. Eight had high serum TSH values by 6 months, and in four the high values were detected between 9 and 18 months. Three patients had clinical hypothyroidism, and five had biochemical hypothyroidism. The serum TSH values in these eight patients ranged from 5.6 to 78 mU/L. The other four patients had transient hypothyroidism (a first high serum TSH value 1 to 19 months after surgery, and normal serum TSH values 5 to 28 months after surgery).
The review of the operative specimens revealed 3+ or 4+ lymphocytic infiltration in 14 patients (21 percent). They included 4 of the 12 patients (33 percent) with hypothyroidism, and 10 of the 54 patients (18 percent) who did not have hypothyroidism.
The conclusions of the study. Patients with a benign thyroid nodule who undergo thyroid lobectomy may have hypothyroidism, especially those with marked lymphocytic infiltration of the surgically removed thyroid tissue.
The original article. Piper HG, Bugis SP, Wilkins
GE, Walker BA, Wiseman S, Baliski CR. Detecting and defining hypothyroidism
after hemithyroidectomy. Am J Surg 2005;189:587-91.
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| Thyroid Digest Index | | | July 2005 Thyroid Digest |
