Preoperative Serum Thyroid-stimulating Hormone Levels Research Articles

Clinical and molecular features of progressive papillary thyroid microcarcinoma.

In recent decades, the prevalence of thyroid cancer has risen substantially, with papillary thyroid microcarcinoma (PTMC) constituting over 50% of cases. Although most PTMCs exhibit indolent growth and a favorable prognosis, some present an increased risk of recurrence and an unfavorable prognosis due to high-risk characteristics such as lymph node metastasis, extrathyroidal extension, and distant metastasis. The early identification of clinically progressing PTMC remains elusive. In this review, we summarize findings from PTMC progression-related literature, highlighting that factors such as larger tumor size, cervical lymph node metastasis, extrathyroidal extension, younger age, higher preoperative serum thyroid-stimulating hormone levels, family history, and obesity positively correlate with PTMC progression. The role of multifocality in promoting PTMC progression, however, remains contentious. Furthermore, recent studies have shed light on the impact of mutations, such as BRAF and TERT mutations, on PTMC progression. Researchers have identified several mRNAs, non-coding RNAs, and proteins associated with various features of PTMC progression. Some studies propose that peripheral and tumor tissue-infiltrating immune cells could serve as biomarkers for the clinical progression of PTMC. Collectively, these clinical and molecular features offer a rationale for the early detection and the development of precision theranostic strategies of clinically progressive PTMC.

Assessment of Preoperative TSH Serum Level and Thyroid Cancer Occurrence in Patients with AUS/FLUS Thyroid Nodule Diagnosis.

Thyroid-stimulating hormone (TSH) is a growth factor associated with the initiation and progression of well-differentiated thyroid cancer (WDTC). Atypia of undetermined significance and follicular lesion of undetermined significance (AUS/FLUS) are the most uncertain cytological diagnoses of thyroid nodules. The aim of the study was to determine the association of histopathological diagnosis with preoperative serum TSH levels in patients with AUS/FLUS thyroid nodule diagnosis. Among 5028 individuals with thyroid nodules, 342 (6.8%) with AUS/FLUS diagnoses were analyzed. The frequency of all histopathology diagnoses was assessed for associations with preoperative serum TSH levels. The median TSH concentration was significantly higher in patients with AUS/FLUS diagnosis and histopathology of WDTC than in patients with the same cytology result and histopathology of a benign tumor (p < 0.0001). The diagnostic potential of serum TSH level was determined to evaluate risk of malignancy in patients with thyroid nodules classified into the Bethesda III category. ROC analysis showed the TSH concentration at a cutoff point of 2.5 mIU/L to be an acceptable prognostic factor for WDTC. For this optimal cutoff point, the AUC was 0.877, the sensitivity was 0.830, and the specificity was 0.902. Preoperative serum TSH levels in patients with AUS/FLUS thyroid tumor diagnosis should be taken into consideration in the decision-making process and clinical management.

Risk factors for thyroid hormone replacement therapy after hemithyroidectomy and development of a predictive nomogram

PurposeHemithyroidectomy is a valid operation to retain functional contralateral thyroid lobe that is indicated for a variety of thyroid diseases. This study aimed at determination of the risk factors for thyroid hormone replacement following hemithyroidectomy and to develop a predictive nomogram.MethodsData of patients treated by hemithyroidectomy for benign thyroid disease between January 2015 and January 2020 were retrospectively analyzed. Baseline characteristics, surgery-related variables, and preoperative and postoperative thyroid function of patients were collected from the case records and compared between patients with postoperative euthyroidism and patients with postoperative hypothyroidism. Postoperative euthyroidism patients without thyroid hormone replacement were compared to those who developed postoperative hypothyroidism with thyroid hormone replacement. The factors associated with thyroid hormone replacement were used to construct a binomial logistic-regression model and visualized as a predictive nomogram to evaluate the risk of thyroid hormone replacement following hemithyroidectomy.ResultsOf the 378 patients (74% female) included in the study, 110 (29.1%) developed postoperative hypothyroidism. Preoperative serum thyroid-stimulating hormone (TSH) > 2.172 μIU/mL was identified as an independent risk factor for postoperative hypothyroidism (odds ratio [OR] = 8.02; 95% confidence interval [CI]: 4.87–13.20; P < 0.001). Of 110 patients with postoperative hypothyroidism, 56 (50.9%) received thyroid hormone replacement. Unilateral thyroid nodule and preoperative serum TSH > 2.172 μIU/mL were independent predictors of postoperative thyroid hormone replacement (P = 0.01, and P < 0.001, respectively). Temporary subclinical hypothyroidism occurred in 12 patients; all 12 reverted to euthyroid state without thyroid hormone replacement. The discriminative effect of the binomial regression model was proved reliable by the Hosmer–Lemeshow goodness-of-fit test (P = 0.503), and predictive ability of the nomogram was satisfactory with a C-index of 0.833.ConclusionsHypothyroidism is common after hemithyroidectomy, and almost half of the patients will need thyroid hormone replacement. Elevated preoperative serum TSH level and unilateral thyroid nodule were independent predictors of thyroid hormone replacement following hemithyroidectomy. The predictive nomogram could be a useful tool for clinical practice.

Serum TSH Levels as a Predictor of Thyroid Malignancy in Euthyroid Patients with a Thyroid Nodule- A Cohort Study

Introduction: Palpable thyroid nodules are a common disorder in the general population. In many cases, the initial presentation of thyroid cancers can be a thyroid nodule. Hence, this is important to distinguish between a benign and a malignant nodule. Fine Needle Aspiration Cytology (FNAC) is the gold standard for evaluating a thyroid nodule. Currently, FNAC is a much more reliable diagnostic technique. However, there are certain limitations of FNAC, which makes the serum Thyroid Stimulating Hormone (TSH) an essential marker in evaluating the thyroid nodule. It has been observed that the frequency of malignancy varies by the serum TSH levels within its normal range itself. Hence, in the present study, authors aim to assess the role of preoperative serum TSH in predicting the malignancy associated with thyroid nodules. Aim: To evaluate the usefulness of preoperative serum TSH levels in patients with ‘nodular thyroid disease’, in prediction of malignancy. Materials and Methods: This is a cohort study conducted over 7 years from January 2014 to December 2020 by the surgery Department of Gandhi Medical College and associated Hospital, Bhopal, India. A total of 50 patients with thyroid nodule(s) having preoperative serum TSH levels within the normal range were included in this study. Serum TSH levels were measured by Electrochemiluminscent Immunoassay (ECLIA). In additaion, patients’ postoperative tissue biopsies were analysed and associated with preoperative serum TSH levels statistically using student’s t-test, Wilcoxon Mann Whitney U-test, Fisher’s exact test, or Chi-square test. Results: A total of 50 patients were included in the study. The age (years) ranged from 19 to 70. Out of 50 patients who participated in the study, 46 (92%) were female. All 50 (100%) patients had thyroid swelling as their initial presentation. Authors subdivided the sample into three groups by the TSH level distribution of the study (category A 0.4-1.4, category B 1.41- 2.5, and category C 2.51-4.0 mIU/L). The serum TSH category C participants had the largest proportion of biopsy impressions as malignant (p-value &lt;0.001). A cut off level of TSH 2.86 mIU/L showed a sensitivity of 58.8% and specificity of 100%. Conclusion: In patients with thyroid nodule/s having serum TSH levels within their normal range, the higher limits of serum TSH levels are associated with an increased risk of thyroid cancer. Preoperative serum TSH levels can be used as an adjunctive diagnostic test for identifying the risk of malignancy associated with a thyroid nodule. It may aid in decision making on diagnostic approaches and may help in making the best therapeutic plans.

A meta-analysis of the influence of body mass index on the clinicopathologic progression of papillary thyroid carcinoma.

Background:Papillary thyroid carcinoma (PTC) incidence has been increasing worldwide. Obesity, that is, having a high body mass index, is associated with the incidence of several cancers including colon, breast, esophageal, and kidney cancer. However, the association between obesity and the clinical features of PTC is still unknown. This study aimed to determine the impact of obesity on the clinical features of PTC.Method:A database search was conducted for articles published up to 2020 on obesity and clinical features of PTC. Data were extracted from articles that met the meta-analysis inclusion criteria.Results:A total of 11 retrospective cohorts and 11,729 patients were included. Obesity was associated with the following variables in PTC patients: older age (difference in means = 1.95, 95% confidence interval [CI] 0.16–3.74, P = .03), male sex (odds ratio [OR] = 3.13, 95%CI 2.24–4.38, P < .00001), tumor size ≥1 cm (OR = 1.34, 95%CI 1.11–1.61, P < .002), multifocality (OR = 1.54, 95%CI 1.27–1.88, P < .0001), extrathyroidal extension (OR = 1.78, 95%CI 1.22–2.59, P = .003) and advanced tumor, node, metastasis stage (OR = 1.68, 95%CI 1.44–1.96, P < .00001). Preoperative serum thyroid-stimulating hormone level (difference in means = 0.09, 95%CI 0.35–0.52, P = .70), Vascular invasion (OR = 0.84, 95%CI 0.56–1.26, P = .41), lymph node metastasis (OR = 1.07, 95%CI 0.87–1.32, P = .50), distant metastasis (OR = 1.14, 95%CI 0.64–2.04, P = .66), and recurrence (OR = 1.45, 95%CI 0.97–2.15, P = .07) were not associated with obesity.Conclusion:Obesity was associated with several poor clinicopathologic prognostic features: older age, male gender, tumor size ≥1 cm, extrathyroidal extension, multifocality, and advanced tumor/node/metastasis stage. However, thyroid-stimulating hormone level, vascular invasion, lymph node metastasis, distant metastasis, and recurrence were not associated with obesity in PTC.

Pre-operative serum TSH levels: A risk factor for advanced metastatic differentiated thyroid carcinoma.

Background and Objective:As the thyroid cancer incidence is increasing, the search for its risk factor is becoming more important. Serum thyroid stimulating hormone (TSH) levels being a growth factor for normal thyroid tissue, is also considered as growth promotor of cancer cells. In our study we aimed for pre-operative serum TSH levels of Differentiated thyroid cancers (DTC) done before their first surgery and determined its association with advanced disease in terms of stage, multifocal disease, lymph node involvement and distant metastasis.Methods:We have conducted a retrospective review of thyroid cancers from 1st January 2008 to 31st December 2017. Out of 281, 142 cases were included according to inclusion criteria. We noted the demographic details of participants, their histopathological diagnosis and serum TSH levels done before first surgery from the medical records. We calculated the stage of tumor through modified American Joint Committee (AJCC) staging system.Results:Out of 147 participants, 89.4% had papillary carcinoma or its variants whereas 10.6% reported follicular carcinoma. The mean pre-op TSH level of the patients included was 2.04 ± 1.79. In addition to the descriptive analysis, the univariate regression analysis revealed that the association of serum TSH levels was found to be statistically insignificant with advanced stage of thyroid cancer, multifocal disease, lymph node metastasis and distant metastasis respectively.Conclusion:The serum TSH levels before surgery was not associated with poor prognosis of differentiated thyroid cancer with respect to higher staging, multifocal disease, lymphatic or distant metastasis.

Clinical features of papillary thyroid carcinoma patients associated with lateral lymph node metastasis in different ages

Objective:To explore the clinical features of papillary thyroid carcinoma(PTC) patients associated with lateral lymph node metastasis(LLNM) in different ages. Method:One hundred and sixtyfive PTC patients associated with LLNM were included in the study and divided into three groups(22-＜30y,30-＜45y and 45-65y). The gender, the number and the ratio of neck lymph node metastasis, maximum tumor diameter, multifocality, preoperative serum thyroid stimulating hormone(TSH), the capsular invasion, extrathyroidal extension and other clinical features in different ages were analyzed.Result:The median age of the patients was 39 years. There were no significant differences in the maximum tumor diameter ＞1cm,multifocality and preoperative serum TSH level among the three groups. The proportion of female patients in 22-＜30y group was higher than the other two groups(all P<0.05).The rate of bilateral lesions in 45-65y group was higher than 22-＜30y group (P<0.01).The rates of the capsular invasion and extrathyroidal extension in 22-＜30y group and 30-45 group were similarly lower than 30-＜45y group(P<0.05).The proportion of the 22-＜30y group coexistent with Hashimoto thyroiditis was higher than the other two groups(P<0.05). When the number of central lymph node metastasis(CLNM)＞3,the proportion of 22-＜30y group were higher than the other two groups(all P<0.01), the 30-＜45y group was the same as higher than 45-65y group(P<0.05); When the ratio of CLNM＞0.35,the proportion of 30-＜45y group was significantly higher than the other two groups(all P<0.05).When the number of LLNM＞6, 22-＜30y group was significantly higher than the other two groups;when the ratio of LLNM＞0.33, 45-65y group was lower than the other two groups(all P<0.05).The total lymph node metastasis＞11, the proportion of 22-＜30y group was significantly higher than the other two groups(all P<0.05), meanwhile 30-＜45y was higher than 45-65y group(P<0.05);when the ratio of total lymph node metastasis＞0.22,45-65y group was significantly higher than the other two groups(all P<0.01).Conclusion: There is a high proportion of female and maximum tumor diameter over 1cm in PTC associated with LLNM. The proportion of coexistent with Hashimoto thyroiditis and the number of lymph node metastasis are much higher in 22-＜30y group. The higher ratio of CLNM is much more common in 30-＜45y group. The bilateral lesions are more likely to occur in 45-65y group, and meanwhile the tumor is more easier to invade the capsular and extrathyroidal construction. The number and the ratio of total lymph node metastasis might be lower in PTC associated with LLNM of older patients.

Association of Preoperative Serum Thyroid-stimulating Hormone Levels with Thyroid Cancer in Patients with Nodular Thyroid Disease.

The aim of the current study was to determine the frequency of carcinoma thyroid among patients presenting with goiter and its association with preoperative serum thyroid-stimulating hormone (TSH) levels. A total of 73 (n = 73) adult patients of either gender with solitary solid cold nodule and multinodular goiter with predominant solid cold nodule were analyzed. All surgically resected samples were sent for histopathology. The frequency of thyroid cancer and its subtypes was noted and tested for association with preoperative serum TSH values. Thyroid cancer was diagnosed in 26% (n = 19) of the patients. In patients with thyroid cancer (n = 19), 73.7% (n = 14) were diagnosed with papillary thyroid cancer and 26.3% (n = 5) were diagnosed with follicular thyroid cancer. Presence of thyroid cancer was found to be significantly associated with preoperative higher mean TSH values (P < 0.05). Higher preoperative serum TSH levels may be useful in predicting thyroid cancer in nodular thyroid disease. Further studies are recommended with different cutoff values of serum TSH and its association with the development and progression of thyroid cancer.

Predictors of Malignancy in Patients with a Thyroid Nodule That Contains Hürthle Cells

Fine needle aspiration cytology of a thyroid nodule with Hürthle cells can be present in both benign and malignant diseases of the thyroid. The aim of this study was to identify the factors that predict malignancy in patients who underwent thyroidectomy with a preoperative fine needle aspiration cytology that contains a predominance of Hürthle cells. Retrospective data collection. Tertiary referral center. Medical records of 70 consecutive patients were reviewed between March 2005 and August 2010. Predictive factors, as well as age, gender, preoperative serum thyroid-stimulating hormone level, the microscopic findings of fine needle aspiration, ultrasonographic appearance, and size and number of nodules in the pathology report, were correlated with final histopathologic diagnosis of benign or malignant disease. Patients' final pathology showed that 21 patients (30%) had malignant disease, of whom 15 patients (71.4%) had papillary carcinoma and 6 patients (28.6%) had Hürthle cell carcinoma. Forty-nine (70%) patients had benign disease (hyperplastic/adenomatoid nodule in 24 patients, Hashimoto thyroiditis in 18 patients, Hürthle cell adenoma in 5 patients, and follicular adenoma in 2 patients). The rate of malignancy was higher in male patients (42.9% vs 28.6%), with nodules measuring ≥2 cm (36.7% vs 25.0%), the presence of a solitary nodule (34.3% vs 27.7%), and the presence of metaplasia in fine needle aspiration (36.4% vs 27.1%), although none was found to be significant (P > .05). Thyroid nodules that are reported in cytology as Hürthle cell lesions require surgery to differentiate benign from malignant disease.

Prognosis of thyroid function after hemithyroidectomy

AbstractIdentify criteria and create a risk scoring system to predict hypothyroidism after hemithyroidectomy. We have retrospectively studied 216 cases of patients with goiter who had undergone hemithyroidectomy from January 2002 to December 2007 at Vilnius University Hospital Santariškių Klinikos. Patients were divided into two groups according to their thyroid function after hemithyroidectomy: 168 (77.8%) patients’ thyroid function was normal (group A), 48 (22.2%) patients had symptoms of hypothyroidism (group B). The relationship between groups and parameters such as patients’ sex, age, patient’s weight, preoperative serum thyroid-stimulating hormone (TSH) level, weight of the remnant gland, ratio of the remaining thyroid gland weight to patient’s weight was statistically analysed. The patients’ mean age was 41.6 ± 14.1 years in group A and 52.9 ± 13.9 years in group B (p=0.0002). The mean preoperative TSH level was 0.79 ± 0.5 mU/L in group A, compared with 1.42 ± 1.00 mU/L in group B (p= 0.005). The mean ratio of the remaining thyroid gland weight to patient’s weight was 0.102 ± 0.053 g/kg in group A and 0.063 ± 0.027 g/kg in group B (p=0.04). The groups did not establish a significant difference between patients’ sex, patient’s weight or weight of the remaining gland. Patient’s age, preoperative serum TSH level, ratio of the remaining thyroid gland weight to patient’s weight is the main factors of hypothyroidism after hemithyroidectomy. A risk scoring system was created to predict hypothyroidism after hemithyroidectomy before the operation.

Preoperative serum thyroid stimulating hormone levels in well-differentiated thyroid carcinoma is a predictive factor for lateral lymph node metastasis as well as extrathyroidal extension in Korean patients: a single-center experience

It has been known that thyroid stimulating hormone (TSH) stimulates the growth or development of thyroid malignancy and higher serum TSH has association with both thyroid cancer incidence and advanced tumor stage. However, the role of TSH in high-risk features of well-differentiated thyroid cancer was not fully evaluated especially in Asian population. The purpose of our study is to evaluate the association of preoperative serum TSH levels with the advance of differentiated thyroid cancer and its high-risk clinicopathological features in Korean patients. We evaluated 554 patients retrospectively who underwent thyroidectomy and diagnosed as differentiated thyroid cancer during a 3-year period at Pusan National University Hospital. The preoperative TSH levels were significantly higher in the patients with extrathyroidal extension (P = 0.002) and those with lateral lymph node metastasis (P = 0.007). As the increase of the serum TSH concentration, there were significant rising trends in the prevalence of extrathyroidal extension (P = 0.009). In the patients with TSH ≥ 2.5 mIU/L, the prevalences of extrathyroidal extension (P = 0.006) and lateral lymph node metastasis (P = 0.024) were also significantly higher. Using multiple logistic regression, preoperative TSH level was a predictive factor for the presence of extrathyroidal extension (P = 0.008) and lateral lymph node metastasis (P = 0.025). Hashimoto's thyroiditis itself was not associated with the status of extrathyroidal extension and lateral lymph node metastasis. In conclusion, preoperative TSH levels were associated with lateral lymph node matastasis, a novel finding, and extrathyroidal extension in well differentiated thyroid cancer and might be useful as a preoperative supplementary marker for determining the optimal extent of differentiated thyroid cancer surgery in Korean patients.

The utility of preoperative serum thyroid-stimulating hormone level for predicting malignant nodular thyroid disease

Introduction The aim of this study was to assess whether serum thyroid-stimulating hormone (TSH) levels are of value in predicting malignancy in patients with nodular thyroid disease (NTD). Methods Patients with NTD and a preoperative TSH level who underwent thyroidectomy between 1990 and 2008 were identified from a prospective database. Age, sex, TSH concentration, nodule size, and pathology were evaluated. Logistic regression analysis was used to determine which factors were predictive of malignancy. Results Six hundred fifty-three patients were analyzed. The overall rate of malignancy was 20%; the rate was highest in patients <30 years (32%). The mean TSH level was higher in the malignant group (5.5 μIU/mL vs 1.4 μIU/mL, P < .0001). The rate of malignancy was 65% in patients with TSH levels >5.5 μIU/mL. Logistic regression analysis revealed that TSH level was the only significant risk factor for malignancy. Conclusion The serum TSH level may be useful in predicting the probability of cancer and optimizing the extent of thyroidectomy in patients with NTD.

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.

Hyperthyroidism after parathyroid exploration

We hypothesized that hyperthyroidism after parathyroid exploration may be an underreported phenomenon with a course more severe than recognized previously. We examined pre- and postoperative thyroid function and outcomes in 199 consecutive patients who, since March 2000, had parathyroid exploration for primary sporadic hyperparathyroidism (HPTH). We excluded patients with prior thyroid or parathyroid surgery, preoperative thyroid medication, concurrent total thyroidectomy, or follow-up <5 months. Of 125 patients with normal preoperative serum thyroid-stimulating hormone levels, 39 (31.2%) were hyperthyroid postoperatively. Mean thyroid-stimulating hormone levels (mean +/- SD) dropped with operation from 2.0 +/- 1.1 microIU/mL to 1.2 +/- 1.4 microIU/mL (P < .0001). Nineteen patients (15%) reported symptoms 1 to 2 weeks after operation. The clinical course of hyperthyroidism typically was short, but 5 patients (4%) had symptomatic hyperthyroxinemia requiring medical therapy. Hyperthyroidism was independent of age, severity of HPTH, anatomic/pathologic features, operative time, and other measures of operative difficulty, but was associated with lithium therapy, bilateral exploration, and absence of concurrent thyroid lobectomy. Risk of hyperthyroidism may be underappreciated after routine parathyroid surgery for HPTH. Use of lithium and degree of dissection appear contributory. Patients undergoing parathyroid exploration need counseling and surveillance for hyperthyroidism, which may be reduced by minimizing the extent of parathyroid surgery.

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.