Hypothyroidism following hemithyroidectomy: a retrospective review.
OBJECTIVE
To investigate the incidence, time to onset, and risk factors for the development of hypothyroidism after hemithyroidectomy.


BACKGROUND
The incidence and risk factors for hypothyroidism in patients undergoing partial thyroid surgery remains unclear. Hypothyroidism is an under appreciated sequel of hemithyroidectomy. The early recognition of this postoperative complication may prevent symptoms of hypothyroidism and recurrent thyroid disease.


METHODS
We conducted a retrospective review of all patients undergoing hemithyroidectomy from August 1992 to June 2006 by a single surgeon. Patients were analyzed for age, sex, family history of thyroid disease, thyroid antibody levels, pre- and postoperative thyroid stimulating hormone (TSH), histologic diagnosis, weight of resected tissue, histologic evidence of thyroiditis, and lag time to diagnosis of hypothyroidism. chi or Fisher exact test or Student t test were performed.


RESULTS
Hypothyroidism was diagnosed in 10.9% of 294 patients. The mean time to diagnosis was 8.2 +/- 10.9 months. The mean thyroxine dose was 69.4 +/- 31.6 micrograms. Patients with postoperative hypothyroidism had a higher incidence of a high-normal preoperative TSH level (TSH: 2.5-4.0 mIU/L, 18.8% vs. 3.8%; P < 0.01), thyroiditis on histology (46.8% vs. 11.8%; P < 0.01) and elevated thyroid antibodies levels (47.8% vs. 11.5%; P < 0.01). Age, gender, family history of thyroid disease, thyroid pathology, and weight of resected tissue were not significant risk factors for hypothyroidism.


CONCLUSIONS
An incidence of 10.9% is higher than anticipated and all patients should have postoperative thyroid function assessment. However, a high-normal preoperative TSH, elevated thyroid antibody levels, and the presence of thyroiditis on histology are indications for close monitoring.
Otolaryngology, Head and Neck Surgery Unit, Monash Medical Centre, Melbourne, Australia. shirleyysu@gmail.com
Shirley Y
SY
Su
Simon
S
Grodski
Jonathan W
JW
Serpell
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013965:Thyroidectomy / Q000009:adverse effects* / Q000379:methods; D013972:Thyrotropin / Q000097:blood; D013997:Time Factors; D055815:Young Adult
D013972:Thyrotropin