Preoperative Thyroid-stimulating Hormone Level Research Articles

Hypothyroidism Following Hemithyroidectomy

To investigate the incidence, time to onset, and risk factors for the development of hypothyroidism after hemithyroidectomy. 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. 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. 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. 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.

Thyroid hormone replacement after thyroid lobectomy

The purpose of this study was to determine the incidence of and identify risk factors for postoperative hypothyroidism in patients undergoing thyroid lobectomy. We retrospectively reviewed patients who underwent a thyroid lobectomy for benign disease from May 2004 to December 2007. Patients with known hypothyroidism or on preoperative thyroid hormone replacement were excluded. In this study, 14.3% of patients developed hypothyroidism and required thyroid hormone supplementation. These hypothyroid patients had a higher mean pre-operative thyroid-stimulating hormone (TSH) and lower mean free thyroxine (T4) serum levels compared with euthyroid patients (TSH, 2.12 vs 1.35 microIU/mL [P = .006]; free T4, 1.03 vs 1.34 ng/dL [P = .01]). When stratified into 3 groups based on their preoperative TSH measurement (< or =1.5, 1.51-2.5, and > or =2.51 microIU/mL), the rate of hypothyroidism increased significantly at each level (13.5%, 20.5%, and 41.3%, respectively [P < .001]). In addition, patients with Hashimoto's thyroiditis were significantly more likely to become hypothyroid (odds ratio, 3.78; 95% confidence interval, 2.17-6.60). After thyroid lobectomy, approximately 1 in 7 patients experience hypothyroidism requiring thyroid hormone treatment. Patients with preoperative TSH levels >1.5 microIU/mL, lower free T4 levels, and Hashimoto's thyroiditis are at increased risk and should be counseled and followed appropriately.

Preoperative Administration of Excess Iodide Increases Thyroid Volume of Patients with Graves' Disease

Preoperative excess iodide administration for patients with Graves' disease has been widely adopted by surgeons to perform surgery safely, because it decreases blood flow in the thyroid. However, surgeons often encounter the enlargement of thyroid volume after iodide administration, which makes surgery even more difficult. In this study, we retrospectively investigated the change in thyroid volume in Graves' disease that was evaluated on ultrasonography between before and after iodide administration. Eighty-nine patients who received iodide administered (KI(+) patients) and 24 in whom iodide was not administrated (KI(-) patients) before surgery for Graves' disease were enrolled in the study. The level of free T4 (FT4) significantly decreased and that of thyroid stimulating hormone (TSH) significantly increased after iodide administration. Average thyroid volume also significantly increased for KI(+) patients after iodide administration and 17% of these patients showed a 30% or more increase in thyroid volume. In KI(-) patients who were preoperatively treated only by anti-thyroid drugs, thyroid volume did not change before surgery. Preoperative TSH levels remained below measurement sensitivity in 37 of KI(+) patients, but the average thyroid volume also significantly increased after iodide administration. These findings suggest that thyroid volume in Graves' disease can increase with iodide administration not only due to TSH stimulation but also due to reasons other than TSH. Surgeons should be careful when preoperatively iodide administering to patients with Graves' disease, especially when the goiter is large.

Hypothyroidism following Hemithyroidectomy for Benign Nontoxic Thyroid Disease

Hypothyroidism following hemithyroidectomy for benign nontoxic thyroid disease is an underappreciated phenomenon. Up until recently, it was common practice for physicians to place post-hemithyroidectomy patients on thyroid suppression therapy during the immediate postoperative period. That practice began to fall out of favor as a result of two developments: (1) the publication of data that put into question the efficacy of levothyroxine therapy for preventing recurrent disease or thyroid growth and (2) a heightened awareness of the morbidity associated with levothyroxine. We conducted a retrospective chart-review study of 58 patients with benign nontoxic thyroid disease who had undergone hemithyroidectomy from 1994 through 2003 at one institution. Of these 58 patients, 14 (24.1%) had become hypothyroid after surgery, including 7 who had been so diagnosed 1 month postoperatively and 6 at 2 months. The remaining 44 patients were euthyroid. The mean preoperative serum thyroid-stimulating hormone (TSH) levels in the hypothyroid and the euthyroid groups were 2.39 and 1.07 microlU/ml, respectively-a statistically significant difference (p < 0.0001). A tissue diagnosis consistent with chronic inflammation (lymphocytic thyroiditis or Hashimoto's thyroiditis) was found in 50.0% of the hypothyroid patients, compared with only 6.8% of the euthyroid patients-again, a significant difference (p < 0.001). No significant difference was seen between the two grqups with respect to age, sex, or the weight of the resected gland. We conclude that hypothyroidism after hemithyroidectomy is not an uncommon occurrence. Apparent risk factors include a high mean preoperative serum TSH level and tissue pathology consistent with chronic inflammation. It may be wise to follow patients with these identifiable risk factors more closely during the postoperative period; monitoring should include scheduled serial serum TSH draws.

Should Female Patients Undergoing Parathyroid-Sparing Total Thyroidectomy Receive Routine Prophylaxis for Transient Hypocalcemia?

Hypocalcemia following parathyroid-sparing total thyroidectomy is frequent and can prolong hospital stay. We undertook this study to identify preoperative predictors of postoperative hypocalcemia useful in the postoperative management of these patients. We examined patients undergoing total thyroidectomy for benign disease with preservation of at least three parathyroids from January 2000 to January 2001. Low serum calcium was considered below 8.0 mg/dL. Age, gender, preoperative serum calcium, thyroid stimulating hormone (TSH), T3, T4, albumin, cholesterol, and tryglicerides were compared in patients with normal and low serum calcium level on the second postoperative day and on discharge day by using chi2 test and a model of logistic regression. Data were reported using their frequency distribution among the two groups of patients. Eighty patients, 60 females (F) and 20 males (M), underwent parathyroid-sparing total thyroidectomy. On second postoperative day, hypocalcemia occurred in 42 patients, and 56 per cent were symptomatic. Only female gender (88% F vs 12% M) (P < 0.05) and TSH <0.27 mUI/mL (38% vs 18%) (P < 0.05) predicted hypocalcemia. Similarly, female gender predicted hypocalcemia in a logistic regression analysis (P < 0.05). On the day of discharge, 22 patients had low serum calcium levels, and 50 per cent were symptomatic. At this time, only TSH value < 0.27 mlU/mL significantly predicted hypocalcemia (48% vs 17%) (P < 0.05). This was confirmed in a logistic regression analysis (P < 0.05). All but one patient (98%) eventually returned to normal serum calium levels. Despite preservation of parathyroids, transient symptomatic hypocalcemia is common after total thyroidectomy. Female gender and low TSH serum level predicted hypocalcemia. Therefore, female patients undergoing total thyroidectomy with preoperative low TSH levels should receive calcium prophylaxis to decrease morbidity, shorten hospital stay, and decrease costs.

Hypothyroidism following hemithyroidectomy: incidence, risk factors and management

Abstract Background Hypothyroidism is often an unrecognized sequela of hemithyroidectomy. The purpose of this study was to determine the incidence, risk factors and management of hypothyroidism occurring after hemithyroidectomy for nodular thyroid disease. Methods All euthyroid patients who underwent hemithyroidectomy from 1992 to 1999 were evaluated for age, sex, preoperative and postoperative serum thyroid-stimulating hormone (TSH) levels, pathology and follow-up. Time of diagnosis and therapeutic doses of thyroid hormone were determined for patients with hypothyroidism. Patients who underwent completion thyroidectomy and those who were on thyroid hormone before operation for TSH suppression or after operation for prevention of recurrent disease were excluded. Results During the study period, 70 euthyroid patients underwent hemithyroidectomy. Postoperative hypothyroidism was diagnosed in 25 (36 per cent) with a mean(s.d.) TSH level of 8·51(6·53) (units l−1). Hypothyroidism was subclinical in 16 and overt in nine patients. There were no significant sex or age differences between hypothyroid and euthyroid patients. The mean(s.d.) preoperative serum TSH level was 1·94(1·00) (units l−1) in patients diagnosed with postoperative hypothyroidism compared with 1·08(0·75) (units l−1) in euthy-roid patients (P &amp;lt; 0·05). Associated lymphocytic thyroiditis was present in ten of 25 hypothyroid patients compared with ten of 45 euthyroid patients (P &amp;gt; 0·05). Nineteen patients received thyroid hormone treatment in doses varying from 0·5 to 1·9 (mean 1·3) g kg−1. Follow-up varied from 1 month to 7 years (mean 1 year). All but one hypothyroid patient was diagnosed within 2 months of surgery. Conclusion Postoperative hypothyroidism occurs in 36 per cent of patients following hemithyroidectomy. It is usually asymptomatic, and can be diagnosed early after surgery. Hypothyroid patients have higher preoperative TSH levels than euthyroid patients and treatment is accomplished with lower than normal replacement doses of thyroid hormone.