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PubMed2001

Ultrasound of thyroid, parathyroid glands and neck lymph nodes.

In the past 15 years high-frequency B-mode sonography and colour-power Doppler have become the most important and most widely employed imaging modalities for the study of the neck, in particular for thyroid gland, parathyroids and lymph nodes. Sonography allows not only the detection but often also the characterization of the diseases of these organs, distinguishing benign from malignant lesions with high sensitivity and specificity, which could be further improved by the employ of ultrasound contrast agents and harmonic imaging. Although no single sonographic criterion is specific for benign or malignant nature of the lesions, the combination of different signs can be markedly helpful to speed up the diagnostic process. Fine-needle aspiration biopsy (FNAB) remains the most accurate modality for the definitive assessment of thyroid gland nodules and of any doubtful case of nodal disease. In association with clinical findings and serum levels of parathormone, FNAB has specificity close to 100% for the characterization of parathyroid adenomas. A combined approach with sonography and FNAB is generally highly effective.

Biopsy, Needle↗
PubMed1996

The expression of parathyroid hormone and parathyroid hormone-related protein in developing rat parathyroid glands.

Secretion of parathyroid hormone-related protein (PTHrP) by sheep fetal parathyroid glands is reported to be an important factor in the maintenance of a placental calcium pump. The aim of the present study was to determine whether the developing rat parathyroid glands express PTHrP or parathyroid hormone (PTH), or both. Hybridisation histochemistry was used to detect transcription of PTHrP and PTH in serial paraffin sections through the 12.5- and 13.5-day rat embryo parathyroid anlage, as well as in sections through the 17.5-day embryonic and adult parathyroid glands. Results show strong expression of PTH in the 13.5-day embryonic parathyroid anlage, as well as in the parathyroid gland of the 17.5-day embryo and adult. Transcription of the PTHrP gene was not detected. The more sensitive technique of reverse transcription PCR was then performed. The pharyngeal region of 11.5-, 12.5- and 13.5-day rat embryos was dissected out and, at each stage, RNA was extracted from these tissues, as well as pooled tissues from the rest of the embryo. RNA that had been extracted from adult thyroid/parathyroid tissue was also tested. After reverse transcription, the resulting cDNAs were amplified by PCR (50 cycles) using specific PTH and PTHrP primers. The results show an abundance of PTH mRNA, specific to the pharyngeal region of the 13.5-day embryo, as well as to adult thyroid/parathyroid tissue. PTHrP expression was detected at very low levels in both parathyroid and extraparathyroid tissues. The presence of immunoreactive PTHrP and immunoreactive PTH in the pharyngeal region and rest of the body of 12.5- and 13.5-day rat embryos was assessed by specific RIAs. Whilst immunoreactive PTHrP was not detected in any of the tissues assayed, immunoreactive PTH was detected only in the pharyngeal region of the 13.5-day embryo. This confirms the results obtained from the gene expression studies. We conclude then that, in the developing rat embryo, PTH rather than PTHrP is more likely to play a role in calcium regulation. This is in contrast with the reported situation in the sheep, and suggests that fundamental species differences in fetal calcium regulation exist in mammals.

Aging↗
PubMed2006

Incidence and location of ectopic abnormal parathyroid glands.

BACKGROUND: Ectopic parathyroid glands are a cause for failed parathyroid exploration. METHODS: Patients with hyperparathyroidism and ectopic parathyroid glands were identified from a parathyroid database. Laboratory data, gland weights, and surgical outcomes were obtained. The locations of the ectopic glands were correlated with results of technetium-99m-sestamibi imaging. RESULTS: Of 231 patients operated on for hyperparathyroidism, 37 (16%) had ectopic parathyroid glands. Ectopic inferior glands (N = 23 [62%]) were intrathymic, n = 7 (30%); anterosuperior mediastinal, n = 5 (22%); intrathyroidal, n = 5 (22%); within the thyrothymic ligament, n = 4 (17%); and submandibular, n = 2 (9%). Ectopic superior glands (N = 14 [38%]) were in the tracheoesophageal groove, n = 6 (43%); retroesophageal, n = 3 (22%); posterosuperior mediastinal, n = 2 (14%); intrathyroidal, n = 1 (7%); in the carotid sheath, n = 1 (7%); and paraesophageal, n = 1 (7%). Sestamibi scans were true-positive in 81%, identifying 13 of 16 retrosternal glands, and false-negative in 19%. CONCLUSIONS: A 16% incidence of ectopic parathyroid glands and a 100% positive predictive value of sestamibi scintigraphy underscore the importance of sestamibi imaging in patients with primary hyperparathyroidism.

Choristoma↗
PubMed2000

Parathyroid glands: combination of (99m)Tc MIBI scintigraphy and US for demonstration of parathyroid glands and nodules.

PURPOSE: To determine the appropriate choice of imaging techniques for localization of nodular lesions of parathyroid glands. MATERIALS AND METHODS: First, computed tomographic (CT), magnetic resonance (MR), ultrasonographic (US), and technetium 99m methoxyisobutyl-isonitrile (MIBI) scintigraphic images in 49 patients with primary hyperparathyroidism were retrospectively evaluated. A single-blind, prospective study that included 16 patients with primary hyperparathyroidism was then conducted. MR, US, scintigraphic, and color Doppler US images of the neck were obtained and analyzed. RESULTS: In the retrospective study, CT, MR imaging, and US had low sensitivity (13%, 17%, and 27%, respectively) and specificity (39%, 65%, and 65%, respectively). Scintigraphy had 57% sensitivity and 85% specificity. In the prospective study, the use of latest-generation MR and US equipment and the participation of experienced operators led to improved sensitivity and specificity for these techniques. The combination of US and scintigraphy resulted in improved sensitivity (96%), specificity (83%), and positive and negative predictive values (88% and 94%, respectively), relative to the results obtained with either method alone. Doppler US was of little help in the setting of small glands. CONCLUSIONS: The combination of (99m)Tc MIBI scintigraphy and US performed by well-trained operators with up-to-date instruments appeared to be the best diagnostic tool for the preoperative diagnosis of parathyroid disease.

Adult↗
PubMed1992

A vasopressor factor partially purified from human parathyroid glands.

Recently, a parathyroid hypertensive factor was postulated to play a role in the pathogenesis of hypertension in genetically hypertensive rats. Therefore it was examined, whether in human parathyroid glands a vasopressor substance can be detected. For this purpose, homogenates of hyperplastic parathyroid glands from 20 patients with tertiary hyperparathyroidism were deproteinized and fractionated by gel chromatography. The fractions obtained were tested for vasopressor activity in isolated perfused rat kidneys. A vasopressor fraction containing substances of 0.6-2.5 kDa was identified in the parathyroid glands. The responsible product was heat sensitive, peptidase-, trypsin- and carboxypeptidase y- sensitive and hydrophilic, as it did not bind to hydrophobic reversed-phase gel. These results suggest that parathyroid glands contain a hydrophilic peptide-like vasopressor substance different from the parathyroid hormone.

Angiotensin II↗
PubMed1998

Localization of abnormal parathyroid glands with jugular sampling for parathyroid hormone, and subtraction scanning with sestamibi or tetrofosmine.

BACKGROUND: Accurate pre-operative localization of abnormal parathyroid glands is an essential prerequisite for elective surgical approaches such as the unilateral approach for treatment of primary hyperparathyroidism. METHODS: In 175 patients undergoing a bilateral neck exploration for primary hyperparathyroidism, localization of abnormal parathyroid glands was performed with jugular venous sampling for parathyroid hormone (PTH, n = 75), subtraction scan with iodine 123 and technetium-99m-sestamibi (MIBI, n = 50), or tetrofosmine (TTF, n = 50). The results of these localization studies were compared with operative findings. RESULTS: The sensitivity of PTH, MIBI, and TTF was 41, 63, and 71%, respectively. The specificity was 90, 98, and 98% and the positive predictive value was 85%, 82%, and 87%, respectively. The smallest abnormal parathyroid that was correctly detected weighed 110 mg with PTH, 118 mg with MIBI, and 70 mg with TTF. Subtraction scan (MIBI and TTF) detected mediastinal glands in five cases out of six. In patients with multiglandular disease, the results of all three studies were severely impaired. CONCLUSIONS: Subtraction scanning with MIBI or TTF, but not jugular sampling for PTH, appeared to be useful for localization of abnormal parathyroid glands in patients with primary hyperparathyroidism. Nevertheless, an elective unilateral approach guided by the localization studies would not have allowed the excision of all abnormal parathyroid glands in patients with multiglandular disease.

Female↗
PubMed1992

Morphological study of parafollicular cells and the parathyroid gland in the house shrew (Suncus murinus).

A morphological study of parafollicular cells in the thyroid gland and parathyroid gland of the house shrew (Suncus murinus) was made. The results indicated that (1) there were two pairs of parathyroid glands which were located in the upper part of the house shrew thyroid gland, (2) the volumes of the house shrew parathyroid glands ranged from 0.014 to 0.079 mm3, (3) the number of parafollicular cells along the follicles was largest in the upper part of the thyroid lobe, while no parafollicular cells were present in the isthmus, and (4) there were about 20 parafollicular cells per 100 follicular cells and 1.519 parafollicular cells per follicle. The number of parafollicular cells per 100 follicular cells was thus about 5 times larger than that in rats and the number of parafollicular cells per follicle about 2.5 times larger than that in rats.

Animals↗
PubMed1998

Comparison of technetium-99m-MIBI, technetium-99m-tetrofosmin, ultrasound and MRI for localization of abnormal parathyroid glands.

UNLABELLED: Abnormal parathyroid tissue can be identified by radionuclide imaging with either 99mTc-MIBI or 99mTc-tetrofosmin. This study compared the relative sensitivity of these two agents to localize parathyroid hyperplasia and adenoma. METHODS: Twenty patients with primary (n = 9) or secondary (n = 11) hyperparathyroidism were studied with 99mTc-MIBI and 99mTc-tetrofosmin parathyroid imaging, ultrasonography and MRI. Radionuclide images of the neck were acquired 10 min and 2-3 hr after radiopharmaceutical injection. The images were visually evaluated for abnormal focal areas of increased tracer localization in the neck and mediastinum. A parathyroid gland/normal thyroid tissue activity ratio (referred to as the P/T uptake ratio) was calculated for each positive scan. RESULTS: Of the 46 parathyroid glands surgically explored, the overall sensitivity and specificity of MIBI imaging were 83% and 83% (38/46); tetrofosmin imaging 87% and 83% (40/46); ultrasonography 78% and 40% (36/46); and MRI 80% and 60% (37/46), respectively. Both radiopharmaceuticals performed well in the nine patients found to have adenoma. The sensitivity and specificity of MIBI imaging were 100% and 100% (9/9); tetrofosmin imaging 100% and 100% (9/9); ultrasonography 78% and 67% (7/9); and MRI 100% and 100% (9/9), respectively. In the 37 glands with hyperplasia, MIBI imaging had a sensitivity of 78% and specificity of 75%; tetrofosmin imaging 84% and 75%; ultrasonography 78% and 43%; and MRI 73% and 60%, respectively. CONCLUSION: All imaging techniques localized abnormal parathyroid glands. The radiotracers have equal sensitivity for the localization of abnormal parathyroid glands. The sensitivity of these tracers was high as compared to ultrasonography or MRI.

Adenoma↗
PubMed1984

Differential calcium response of normal and adenomatous parathyroid glands.

In vitro parathyroid hormone secretion of normal (n = 10) and adenomatous (n = 20) human parathyroid glands was compared in response to different calcium (Ca++) concentrations. The glands, prepared for tissue culture immediately after surgical removal, were incubated under identical conditions for 6 h. The medium was changed hourly and analyzed for PTH and cAMP using radioimmunoassay. During the first 2 h of the experiment, the Ca++ concentrations of all preparations was kept constant at 1.2 mM equivalent to the normal Ca++ level of the intercellular space. The PTH level of the 2nd h was defined as reference value corresponding to 100%. After the 2nd h of incubation the Ca++ concentration in the medium was shifted either to low (0.9 or 0.6 mM) or to high (1.9 or 2.6 mM) values. In low Ca++ concentrations (0.6 mM) the normal parathyroid glands responded by stimulation of the PTH release up to 310% in relation to the reference value, whereas the adenomas enhanced the PTH release to 160% only. The incubations in 0.9 mM Ca++ resulted in a slightly lower degree of stimulation. During the incubation in high Ca++ the PTH secretion was reduced to 28% by normal glands and to 52% by adenomatous parathyroid glands. Movements of cAMP measurements paralleled PTH values. The study provides evidence for an abnormally low responsiveness of parathyroid adenomas to Ca++ when compared with normal glands. The reduction in Ca++ responsiveness of adenomatous cells appears to have a fundamental role in primary hyperparathyroidism since the tumour cells may obviously recognize normal Ca++ levels as 'hypocalcaemic' and react by a stimulated PTH secretion.

Adenoma↗
PubMed2006

Direct injection of calcitriol or its analog into hyperplastic parathyroid glands induces apoptosis of parathyroid cells.

Hyperplasia of the parathyroid gland (PTG) is associated not only with excessive secretion of parathyroid hormone (PTH) but also with changes in the parathyroid cell (PTC) characteristics (i.e. hyperproliferative activity, and low contents of vitamin D and calcium-sensing receptors). Control of PTG hyperplasia is most important in the management of secondary hyperparathyroidism, but the advanced stage of hyperplasia is considered irreversible. In the present study, dialysis patients with PTG hyperplasia underwent direct injection of calcitriol or maxacalcitol (OCT) into the PTG. Ultrasonography showed that this treatment had significantly reduced PTG volume and tissue analysis using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method and DNA electrophoresis indicated that cellular apoptosis had been induced. The mechanism of apoptosis was evaluated in detail in uremic rats fed a high-phosphate diet. OCT or its vehicle was directly injected into the rats' PTGs. In the PTGs treated by OCT, there was a significantly increased number of TUNEL-positive PTCs and DNA electrophoresis revealed the characteristic ladder pattern of DNA fragmentation, both findings indicative of apoptosis. There was also a significant upregulation of both vitamin D and Ca-sensing receptors in the PTCs and a clear shift of the Ca-PTH response curve to the left and downward. None of these findings was observed in the PTGs treated by vehicle. This novel treatment is successful in causing regression of PTG hyperplasia. Thus, it is expected to significantly reduce the PTH level and ameliorate the abnormal bone turnover and mineral metabolism.

Animals↗
PubMed2003

Combined transmission and (99m)Tc-sestamibi emission tomography for localization of mediastinal parathyroid glands.

AIM: Although parathyroid scintigraphy using (99m) Tc-sestamibi is considered the best preoperative localization method for hyperfunctioning parathyroid tissue it lacks the anatomical details required for successful, minimal invasive surgery of ectopic parathyroid lesions. This study presents the role of combined SPECT/X-ray-CT imaging in a single device for localization of mediastinal parathyroid glands. METHODS: (99m) Tc-sestamibi SPECT/X-ray-CT was performed by gamma camera-mounted anatomical X-ray tomography (GMAXT; GE Medical systems, Millenium VG with Hawkeye) in four patients with ectopic parathyroid glands (two patients with primary, two with persistent secondary hyperparathyroidism). The device contains an X-ray tube and a set of detectors that rotate around the patient combined with a gamma camera. For comparison with GMAXT addition-ally high resolution computed tomography images of the neck and mediastinum were performed. RESULTS: Correct preoperative localization was achieved. The parathyroid glands were located in the anterior mediastinum. High resolution computed tomography could not provide further details. Three patients were operated by a minimal invasive open and one patient by a transsternal approach because of concomitant aortic valve replacement. CONCLUSION: (99m)Tc-sestamibi/X-ray-CT fusion imaging in a single device can accurately localise ectopic or supernumerary mediastinal parathyroid tumours in primary and secondary hyperparathyroidism. Morbidity,radiation exposure, time, and costs are reduced by avoiding multiple diagnostic examinations and minimal invasive parathyroid surgery becomes possible.

Choristoma↗