Modified Larssen solution (MLS)-fixed cadaver model for transoral endoscopic thyroidectomy vestibular approach (TOETVA) education: a feasibility study.

BACKGROUND: Training formats for transoral endoscopic thyroidectomy vestibular approach (TOETVA) are limited. Our aim was to create and investigate a TOETVA training model for general and ENT surgeons. METHODS: A total of 15 modified Larssen solution (MLS) human cadavers were used in the study. A day duration TOETVA human cadaver workshops were offered in two years consecutive. Post-training verbal and online questionnaires were applied to all trainers to evaluate course structure and program, organoleptic characteristics of MLS-fixed human cadavers, and TOETVA training effectiveness. Cost assessment is included in the study. RESULTS: Ninety-eight participants, i.e., 14 trainers and 84 hands-on (HO) and observer (OB) trainees, attended the workshops, completed the tasks assigned, and fulfilled the questionnaires. Implementation of all steps of TOETVA was approved positively by 89.8% of all participants, 94.4% of HO, and 83.3% of OB trainees. Regarding human cadaver and teaching quality, 10.8 ± 0.8 (10-12) human cadavers were "practical" by 13.2 (94.5%) of the trainers, and by 33.3 (92.5%) of the trainees for all steps of TOETVA. The cadavers were stored for 4.53 years and used 6.27 times repeatedly for endoscopic workshops and research studies. TOETVA workshop cost with repeatable use of MLS-fixed human cadaver is half of other performed TOETVA workshops. CONCLUSIONS: A TOETVA human cadaver workshop model has not been reported yet. Our findings suggest the feasibility of MLS-fixed human cadaver model for training of TOETVA, preserve the organoleptic properties necessary for the implementation of surgical steps, and reduce the cost.

Trans-oral endoscopic thyroidectomy vestibular approach (TOETVA) for the pediatric population: a multicenter, large case series.

INTRODUCTION: A cervical scar has been shown to have an impact on the quality of life of children undergoing thyroid surgery. Transoral endoscopic vestibular thyroidectomy via the vestibular approach (TOETVA) offers the absence of a cutaneous incision, and has not been described to date in the pediatric population. OBJECTIVE: To describe the first series of TOETVA in a pediatric population. PATIENTS AND METHODS: A retrospective, multicenter study, including all patients > 18 years old who underwent TOETVA. Data was prospectively collected and included demographics, preoperative ultrasound, cytology and indications for surgery. Intraoperative parameters included length of surgery and complications, with final pathology and postoperative course also reviewed. TOETVA surgical success was defined as completion of surgery via this approach. RESULTS: Forty-eight children were included. Of these, 43 (89.5%) were girls. The median age was 16 years (range 10-17). The most common indication for surgery was a benign thyroid nodule (n = 26, 54.1%). Eleven patients (22.9%) had papillary thyroid carcinoma on final pathology, of which 90.9% (10/11) were diagnosed pre-operatively based on FNA cytology. Hemithyroidectomy was performed in 36 patients (75%). All surgeries were completed endoscopically. The mean malignant tumor size was 1.4 ± 0.4 cm and all tumors were completely excised with clean margins. No permanent complications were documented. A single patient (2.1%) had transient RLN injury (1.6%, 1/60 nerves at risk). Transient hypocalcemia was documented in 4 of the 12 patients undergoing total thyroidectomy (33.3%). Transient mental nerve injury/chin hypoesthesia was documented in 2 patients (4.2%). CONCLUSIONS: TOETVA appears to be a feasible and safe approach for thyroidectomy in the pediatric population in carefully selected cases, and may be discussed with patients and parents as an alternative for the trans-cervical approach.

One hundred and one consecutive transoral endoscopic parathyroidectomies via the vestibular approach for PHPTH: a worldwide multi-institutional experience.

IMPORTANCE: The transoral vestibular approach for thyroid and parathyroid surgery is being adopted rapidly world-wide. Currently there is a paucity of information on this approach for primary hyperparathyroidism (PHPTH). If this approach is safe and efficacious it would provide patients a completely scarless option for parathyroidectomy. OBJECTIVE: To determine whether parathyroidectomy via the transoral vestibular approach can be successfully done in a safe and efficient manner. DESIGN: Consecutive case series of 101 transoral parathyroidectomies performed over a two-year period. SETTING: Multi-institutional, academic, high-volume transoral thyroidectomy centers from the USA, Israel, and Thailand. PARTICIPANTS: A consecutive series of adult patients with a biochemical diagnosis of classic PHPTH and who met criteria for parathyroidectomy based on established international consensus for surgery for PHPTH. All patients also had well-localized single adenomas on at least two preoperative imaging studies. INTERVENTION: Transoral endoscopic parathyroidectomy vestibular approach. MAIN OUTCOMES AND MEASURES: Surgical success rate defined by immediate intra or post-operative return to normal PTH values. Surgical complications including recurrent laryngeal nerve injury, permanent hypoparathyroidism, and infection. RESULTS: Of the 101 consecutive transoral parathyroidectomy patients 84% were female with an average age of 54.23 ± 11.0 years and an average BMI of 27.35 ± 6.19. Ninety-nine out of the 101 patients had immediate return to normal PTH after resection for a surgical success rate of 98%. There were no permanent recurrent laryngeal nerve injuries, one temporary nerve palsy, and no permanent hypoparathyroidism. The median operative time dropped from 130.5 min (IQR 86) to 66.5 min (IQR 56) between the first- and second-half of cases. CONCLUSION AND RELEVANCE: Transoral endoscopic parathyroidectomy via the vestibular approach is a scarless method of removing parathyroids that is clinically feasible, safe, and efficacious and is a reasonable option for focused minimally invasive parathyroidectomy that can be offered to select patients with PHPTH.

Transoral robotic thyroidectomy versus transoral endoscopic thyroidectomy: a propensity-score-matched analysis of surgical outcomes.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach (TOETVA) has been shown to be safe and has similar outcomes as open thyroidectomy for selected patients. It is not clear if transoral robotic thyroidectomy (TORT) may extend transoral endoscopic thyroidectomy to more complex thyroid operations. The study aimed to compare the safety and outcomes of TORT with those of TOETVA. METHODS: We retrospectively reviewed all patients who had TORT and TOETVA performed by a single surgeon from June 2017 to May 2019. Intrathoracic goiter and combined operations were excluded. Surgical outcomes were compared after propensity score matching. Learning curves, as measured by operating time, were evaluated. RESULTS: A total of 150 patients underwent 154 transoral (55 TORT and 99 TOETVA) thyroidectomy. Of the 154 operations, 28 (18.2%) were bilateral total thyroidectomy and 126 (81.8%) were unilateral thyroid lobectomy. After propensity score matching, we found a longer operative time (median [interquartile range]) for TORT (n = 53) than for the TOETVA (308 [284-388] vs 228 [201-267] min, P < 0.001). Blood loss and visual analog scale scores for pain were not significantly different between the two groups. Central neck lymph node dissection was performed more frequent in the TORT group (28 of 53 [52.8%] vs 10 of 53 [18.9%], P = 0.001), and when performed, the numbers of total and positive lymph nodes did not differ significantly between the two groups. The rates of hypoparathyroidism and recurrent laryngeal nerve injury did not differ significantly between the two groups. There was no conversion to open thyroidectomy, mental nerve injury, or surgical site infection. The learning curve for TORT was 25 cases, but no obvious learning curve was observed for TOETVA. CONCLUSIONS: TORT requires a longer operative time, but is as safe as TOETVA and may be useful for more complex thyroid operations.

Transoral endoscopic vestibular approach for thyroidectomy and parathyroidectomy - From promise to practice.

OBJECTIVES: To describe the evolution and recent series on transoral endoscopic vestibular approach thyroidectomy and parathyroidectomy (TOET/PVA). DATA SOURCES: PubMed, Google Scholar. REVIEW METHODS: Review of the available English literature. RESULTS: TOET/PVA may offer several advantages over other remote access thyroidectomy approaches and has been adopted by many centers worldwide with excellent success rates. Indications include benign disease and early thyroid cancer patients. Complication rate is comparable to the trans-cervical approach. The suggested framework has been validated in recent studies and its feasibility confirmed. CONCLUSION: TOET/PVA has now been used to treat thousands of patients worldwide due to low cost, short learning curve and excellent cosmetic outcomes. Further studies will be necessary to demonstrate oncologic non-inferiority and also the true value that is added by the approach.

Lessons Learned from the Transoral Endoscopic Thyroidectomy with Vestibular Approach (TOETVA) for the Treatment of Thyroid Carcinoma.

BACKGROUND: Early detection of thyroid carcinoma has become commonplace. Consequently, the endoscopic approach has become a widely used method. OBJECTIVE: Our aim was to report our experience with the transoral endoscopic thyroidectomy vestibular approach (TOETVA). METHODS: We reviewed the records of 46 patients who underwent TOETVA. Only patients with no regional lymph node metastases (N0) and fine needle aspiration biopsy-confirmed thyroid cancer were included. The surgical technique used was as described by Angkoon Anuwong. RESULTS: Forty-six patients with a mean age of 43.6 years (range 17-71) were included (37 women and 9 men). The mean time of surgery was 207 min (range 95-345), and the conversion to open thyroidectomy rate was 13% (six cases). CONCLUSION: TOETVA is an acceptable approach for thyroid carcinoma. Poorly differentiated cancer, as well as extrathyroidal extension, result in patients being unsuitable for TOETVA. It is imperative to identify the circumstances under which conversion to open thyroidectomy must take place.

Transoral endoscopic thyroid surgery in a Korean population.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach is expected to be a safe alternative to open surgery for certain patients and has been used increasingly by several surgeons around the world for the past 2 years. The purpose of this paper is to review our 2-year experience and describe in detail our preoperative considerations, patient selection, operating room settings, anesthetic considerations, surgical technique, postoperative management, and outcomes. METHODS: We reviewed the medical records of 65 consecutive patients who underwent transoral endoscopic thyroidectomy between July 2016 and May 2018 in our hospital. RESULTS: We have performed 65 thyroid surgeries (54 thyroid lobectomies, 1 completion thyroidectomy, and 10 total thyroidectomies) in 64 patients. Postoperative pathology revealed papillary carcinoma in 55 patients (84.6%), follicular carcinoma in two (3.1%), hyalinizing trabecular tumor in one (1.5%), and other benign tumor in seven (10.8%). All surgical margins were negative. Two (3.1%) patients developed transient vocal cord palsy but recovered within 2 months. One (1.5%) patient with vocal cord palsy had not recovered by 3 months after surgery. Five (7.7%) patients who underwent total thyroidectomy developed transient hypocalcemia but recovered within 2 months. CONCLUSION: Although transoral thyroid surgery is a relatively recent technique requiring further validation, it affords several advantages. Transoral thyroid surgery has not yet been universally accepted, but may be the best choice for thyroid surgery in the future.

Transoral robotic thyroidectomy: lessons learned from an initial consecutive series of 24 patients.

BACKGROUND: Transoral thyroid surgery is an ideal method for minimally invasive thyroidectomy, as there is less flap dissection during the procedure and no postoperative scars. Nonetheless, technical obstacles have precluded the wide dissemination of this procedure. We present the surgical procedures and outcomes of transoral robotic thyroidectomy (TORT). METHODS: From September 2012 to June 2016, we performed TORT at Korea University Hospital. We used three intraoral ports and a single axillary port for the system's four robotic arms. The surgical outcomes were retrospectively reviewed. RESULTS: Twenty-four female patients (mean age 39.6 ± 11.6 years; mean tumor size 1.0 ± 1.3 cm) underwent unilateral thyroid lobectomies with or without ipsilateral central neck dissection. Twenty patients had papillary thyroid carcinomas (PTC), three had benign nodules, and one had a follicular thyroid carcinoma. The mean surgical time was 232 ± 41 min; the mean hospital stay was 3.3 ± 0.8 days. The number of retrieved central lymph nodes in the PTC patients was 4.7 ± 3.2. There were no reports of transient or permanent vocal cord palsy, recurrence, or mortality during the median follow-up period of 16.8 months. Paresthesia of the lower lip and the chin due to mental nerve injury was observed in nine of the first 12 patients (six transient, three permanent), but no further reports of paresthesia were recorded after patient 12, when the locations of the intraoral incisions were modified. CONCLUSIONS: TORT is feasible and safe for selected patients after technical refinements, and can be a potential alternative approach for scarless thyroid surgery.

Transoral endoscopic thyroidectomy vestibular approach (TOETVA): indications, techniques and results.

INTRODUCTION: The Transoral Neck Surgery (TONS) Study Group was established at the 1st International Thyroid NOTES Conference in February 2016 with the intention of standardizing and refining thyroid NOTES techniques, including both transoral endoscopic and robotic thyroidectomy approaches. Herein, the authors report the modification of indications, preparation, and step-by-step explanations for operative techniques, as well as results and postoperative care for transoral endoscopic thyroidectomy vestibular approach (TOETVA). METHODS: Between February 2015 and December 2015, a total of 200 patients comprising 8 males (4%) and 192 females (96%) underwent TOETVA using 3 laparoscopic ports inserted at the oral vestibule. Of these patients, 111 presented with single thyroid nodules (55.5%), while 66 patients had multinodular goiters (33%), 12 had Graves' disease (6%) and 11 had papillary microcarcinoma (5.5%). The CO2 insufflation pressure was maintained at 6 mmHg. Each surgery was performed using laparoscopic instruments and ultrasonic devices. RESULTS: TOETVA was performed on 200 consecutive patients. No conversion to conventional open surgery was necessary. Average tumor size was 4.1 ± 1.78 cm (1-10 cm). Median operative time was 97 ± 40.5 min (45-300 min). Median blood loss was 30 ± 46.25 mL (6-300 mL). Mean visual analog scale measurements were 2.41 ± 2.04 (2-7), 1.17 ± 1.4 (0-5), and 0.47 ± 0.83 (0-3) on the first, second, and third days, respectively. Temporary hoarseness and hypoparathyroidism occurred in 8 patients (4%) and 35 patients (17.5%), respectively. No permanent hoarseness or hypoparathyroidism occurred. Mental nerve injury occurred in 3 patients (1.5%). One patient (0.5%) developed a post-operative hematoma that required open surgery. No infection was identified. CONCLUSION: TOETVA was shown to be safe and feasible with a reasonable surgical duration and minimal pain scores. This approach shows promise for those patients who are motivated to avoid a neck scar.

How I Do It: New Dissector Device Allows for Effective Operative Field in Transoral Endoscopic Thyroid Surgery Using Vestibular Approach.

BACKGROUND: Minimally invasive thyroid and parathyroid resections are rarely performed. Promising new endoscopic transoral approaches to the anterior neck (transoral endoscopic thyroidectomy vestibular approach [TOETVA]) have been described with good results and few complications. This study evaluates a new device to allow the safe entrance of trocars in the subplatysmal space for TOETVA in a cadaver model. METHODS: The technique was performed in 4 unilateral thyroidectomies in female cadavers. The technical steps consisted of a 10-mm incision made at the center of the oral vestibule followed by subplatysmal hydrodissection. The blunt dissector is a metallic stick with an olive at the end and promotes progressive gain in subplatysmal space enlarging the operative field. The instrument was inserted creating a space below the platysma to the anterior neck and the strap muscles. Three trocars were inserted in the vestibular area. The dissection begins by cutting the linea alba cervicalis. The isthmus was dissected and transected. Anatomical structures as the superior thyroid artery, parathyroid glands, and the recurrent laryngeal nerve could be safely identified with magnified vision. RESULTS: Optimal operative field due to subplatysmal dissection by the device allowed for exposition of thyroid and parathyroid glands in all cases. Unilateral thyroidectomy was performed in a mean of 54 minutes with excellent aesthetic results. CONCLUSIONS: The new device is a promising feature to allow safe transoral thyroid surgery in a cadaver model. Further studies in clinical series are needed to evaluate the broad application of the device.

Bilateral areolar endoscopic Sistrunk operation: a novel technique for thyroglossal duct cyst surgery.

BACKGROUND: Sistrunk operation of the thyroglossal duct is a procedure for the removal of a cyst, the middle part of the hyoid bone and tract towards the foramen caecum. Unavoidably, this procedure results in a scar on the skin in the neck area. By performing a bilateral areolar endoscopic Sistrunk operation, this study is the first to develop a procedure that can solve the aesthetic problem. This operation results in both an excellent cosmetic result and the successful treatment of TGDC. METHODS: A three-port technique was performed in this operation: 10-mm port for 30°, 10-mm laparoscope, 5-mm port for the instrument at the left circumareolar area and 5-mm port located at the right circumareolar area. Insufflation pressure of CO2 gas was set at 6 mm Hg. The surgical working space was located over the breast tissue and pectoralis muscles, towards the anterior neck to the hyoid bone. The steps employed for resection were similar to a conventional Sistrunk operation using standard laparoscopic instruments and hook scissors. RESULTS: A series of 11 patients were successfully treated using this novel technique with neither conversion to open surgery nor surgical complications. Average operative time was 88.54 min (ranging from 60 to 130 min). Average blood loss was 35 mL. (ranging from 15 to 67 mL). Patients were discharged in an average of 2.36 days after the procedure (ranging from 2 to 3 days). CONCLUSION: This novel technique for TGDC Sistrunk surgery using an areolar approach is feasible, safe and effective. The benefit of this technique is the cosmetic result, which leaves no scarring on the neck after wound healing and may provide a new method for optimal aesthetic results.

Transoral endoscopic parathyroidectomy vestibular approach: a novel scarless parathyroid surgery.

BACKGROUND: Natural orifice transluminal endoscopic surgery developed for neck surgery become increasing popular. Herein, an innovative transoral endoscopic parathyroidectomy vestibular approach (TOEPVA) was developed for primary hyperparathyroidism (PHPT) and renal hyperparathyroidism (rHPT). METHODS: Incisions were made at the oral vestibule under the inferior lip. A 10-mm trocar was inserted through the center of the oral vestibule with two 5-mm trocars laterally. The subplatysmal space was created down to the sternal notch, and carbon dioxide pressure was insufflated at 6 mmHg to maintain the working space. Parathyroidectomy was performed using laparoscopic instruments. Intraoperative parathyroid hormone level and frozen section were conducted. Autotransplantation of the parathyroid gland was performed at the non-dominant forearm in an rHPT patient. RESULTS: From March 2015 to June 2016, TOEPVA was successfully performed in 12 patients (six PHPT and six rHPT). The mean operative time for parathyroidectomy in PHPT patients was 107.5 min (range 88-127) and 185.8 min in rHPT patients (range 155-214). One patient experienced a transient recurrent laryngeal nerve injury which was spontaneously resolved within 1 month. No permanent recurrent laryngeal nerve injury was found. Serum calcium level returned to normal range in all patients. The serum parathyroid hormone level of the PHPT and the rHPT group at 30 days was 36.38 ± 7.1 pg/mL (range 27.7-46.5) and 60.35 ± 15.94 pg/mL (range 38.7-87.2), respectively. The postoperative cosmetic outcome was excellent. No mental nerve injury or infection was found. CONCLUSIONS: TOEPVA is a feasible, safe, and reasonable surgical option for patients with hyperparathyroidism, especially those with cosmetic concerns.

Gastric acid secretion and gastrin release during continuous vagal neuromonitoring in thyroid surgery.

PURPOSE: The vagus nerve (VN) has essential regulatory roles in the gastric acid secretion and gastrin release. Continuous intraoperative neuromonitoring (CIONM) via VN stimulation is a promising technique in thyroid surgery because it potentially avoids injury to the recurrent laryngeal nerve. However, no studies have investigated changes in gastric acid secretion and gastrin release during CIONM. METHOD: This prospective study of 58 thyroid surgery patients compared gastric acid and serum gastrin at five time points: (1) before skin incision, (2) after baseline calibration of CIONM probe, (3) +20 min from baseline, (4) before probe removal, and (5) after extubation. Patients were excluded if they had any history of using tobacco, acid suppression medications, or drugs that affect gastric motility. Patients were also excluded if they had any history of gastroesophageal reflux symptoms, gastroesophageal reflux disease, peptic ulcer disease, helicobacter pylori infection, or chronic kidney disease. RESULTS: Non significant differences in mean gastric pH values were observed at all time points, i.e., (1) before skin incision (2.2 ± 0.2; p = 0.50), (2) after baseline calibration of CIONM probe (2.0 ± 0.8; p = 0.62), (3) +20 min from baseline (2.5 ± 0.5; p = 0.24), (4) before probe removal (2.9 ± 0.9; p = 0.52), and (5) after extubation (2.6 ± 1.0; p = 0.60). Comparisons of pH monitoring parameters revealed no significant differences in age, gender, side of CIONM (left vs. right), sequence of CIONM, or duration of CIONM. Gastrin values were normal in sequential determinations and did not significantly differ at any time points. CONCLUSIONS: CIONM performed via VN stimulation during total thyroidectomy in healthy patients does not influence gastrin secretion and gastric pH.

Transoral Endoscopic Thyroidectomy Vestibular Approach (TOETVA): From A to Z.

We depict the transoral endoscopic thyroidectomy vestibular approach (TOETVA). Patient selection criteria are (1) ultrasonographically (US) estimated thyroid diameter no larger than 10cm, (2) US estimated gland volume ≥45mL, (3) nodule size ≥5mm, (4) a benign tumor, such as a thyroid cyst, single-nodular goiter, or multinodular goiter, (5) follicular neoplasm, and (6) papillary microcarcinoma without evidence of metastasis. TOETVA is carried out through a three-port technique placed at the oral vestibule, one 10mm port for 30° endoscope and two additional 5mm ports for dissecting and coagulating instruments. CO2 insufflation pressure is set at 6mmHg. An anterior cervical subplatysmal space is created from the oral vestibule down to the sternal notch, laterally to the sternocleidomastoid muscles bilaterally. Thyroidectomy is done fully endoscopically using conventional endoscopic instruments. Intraoperative neuromonitoring is used for identification and dissecting and monitoring both the superior and inferior laryngeal nerves.

Topographical Variations between Splenic Flexure and Spleen: A Study with CT Image-Based Reconstruction.

INTRODUCTION: An issue that is seldom seen in the literature relates the detailed relationship of the splenic flexure (SF) and the spleen-both carefully examined-with a prospective approach in patients undergoing computer tomography (CT) scan. MATERIALS AND METHODS: SF localization has been searched and examined in 120 consecutive CT scans. Several different variables (age, gender, BMI, indication of CT scan, etc.) have been considered. In cooperation with the Radiology Division, we brought to completion a dedicated topographic outline, with the purpose of providing a detailed classification for SF localization. RESULTS: The SF lies, in 52% of cases, in what we called the inferior (I) position, below the spleen. Other categories of our classification were anterior (A) and posterior (P) positions, which were found respectively in 42% and 8% of analyzed cases. Considering all the variables given, we did not find any significant statistical correlation (p > 0.05). CONCLUSIONS: This study was carried out to classify types of SF in terms of its positional relationship with the spleen. We investigated 120 CT scans and classified the SF into three types, according to its localization: inferior (I), anterior (A), and posterior (P) types. A better understanding of the anatomic variability in SF may be useful for minimizing complications and performing an accurate surgical dissection.

Transoral Endoscopic Thyroidectomy Vestibular Approach: A Series of the First 60 Human Cases.

BACKGROUND: Natural orifice transluminal endoscopic surgery has been adopted for thyroid surgery because of its potential for scar-free operation. However, the previous technique still has some limitations. Thus, we present our initial experience in transoral endoscopic thyroidectomy vestibular approach (TOETVA). METHODS: From April 2014 to January 2015, we used a three-port technique through the oral vestibule, one 10-mm port for laparoscope and two additional 5-mm ports for instruments. The CO2 insufflation pressure was set at 6 mm Hg. An anterior cervical subplatysmal space was created from the oral vestibule down to the sternal notch. The thyroidectomy was done endoscopically using conventional laparoscopic instruments and an ultrasonic device. RESULTS: A series of 60 procedures were accomplished successfully. 42 patients had single-thyroid nodules, and a lobectomy was performed. 22 patients had multinodular goiters and two patients had Graves' disease, with total thyroidectomy or Hartley-Dunhill procedures performed. Two had papillary thyroid carcinoma, and total thyroidectomy with central node dissection was performed. The median operative time was 115.5 min (range 75-300 min). The median blood loss was 30 mL (range 8-130 mL). Two patients experienced a transient hoarseness, which was resolved within 2 months. One patient experienced a late postoperative hematoma, which was treated conservatively. No mental nerve injury or infections were found. The patients were discharged in an average of 3.6 days (range 2-7 days) postoperatively. CONCLUSION: TOETVA is safe and feasible, resulting in no visible scarring. This technique may provide a method for ideal cosmetic results.

Validation of appropriate reference genes for gene expression studies in human thyroid gland using real-time RT-PCR.

BACKGROUND: Gene-expression analysis is increasingly important in biological research, with real-time reverse transcription PCR (qRT-PCR) becoming the method of choice. The selection of reference genes is critical for gene expression studies because the expression of these genes may vary among tissues or cells and may change under certain circumstances. However there has not been any study that compares the stability of these reference genes in human thyroid specimens. Therefore, the authors studied the stability values and the appropriate reference genes expressed in thyroid specimens. MATERIAL AND METHOD: 25 human thyroid specimens were prospectively collected and extracted for their RNA. The candidate reference genes (hypoxanthine phosphoribosyl-transferase1 (HPRT1), ribosomal protein LI3a (RPLIA), beta-2-micro-globulin (B2M), beta-actin (ACTB) and glyceraldehyde-3-phosphate dehydrogenase (GAPD)) were amplified from these thyroid specimens using real-time RT-PCR. The stabilities of these candidate reference genes were analyzed using Normfinder software. RESULTS: The authors found that HPRT1 has the highest stability value (40.38 x 10(9)) while GAPD has the lowest stability value (85.46 x 10(7)). Therefore GAPD is the most stably expressed gene in thyroid specimens. CONCLUSION: Of the 5 genes studied, GAPD was found to be the best reference gene for gene expression studies in the thyroid gland. The present results may facilitate the choice of reference genes for expression studies in thyroid diseases.