Radioimmunoassay of Parathyroid Hormone in Primary Hyperparathyroidism: Studies after Removal of Parathyroid Adenoma

Parathyroid hormone has been measured by radioimmunoassay in eight patients with hyperparathyroidism due to parathyroid adenoma. Secretion of hormone by the adenomatas was demonstrated direct by estimating the arteriovenous gradient of parathyroid hormone across the tumours. Serial estimations following surgical removal of the adenoma showed a rapid fall in the concentration of circulating parathyroid hormone. The calculated half-life of endogenously secreted parathyroid hormone in man varied from 11·4 to 28·8 min., with a mean of 19·8 min.     

KDIGO Categories of Glomerular Filtration Rate and Parathyroid Hormone Secretion in Primary Hyperparathyroidism

Objective: The recent Fourth Workshop on the Management of Asymptomatic primary hyperparathyroidism (PHPT) maintained the threshold of 60 mL/min for decreased renal function, below which surgery is recommended. This study investigated the relationship between different stages of renal insufficiency and parathyroid hormone (PTH) levels in an updated case series of PHPT patients.Methods: This was a retrospective, cross-sectional study involving 379 consecutive PHPT patients. Biochemical evaluation included total and ionized serum calcium, phosphate, creatinine, immunoreactive intact PTH, and 25-hydroxyvitamin D₃ (25[OH]D₃) levels in the fasting state. Glomerular filtration rate (GFR) was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.Results: Mean CKD-EPI estimated GFR was 81.9 ± 20.3 mL/min/1.73 m², and median GFR was 84.0 mL/min/1.73 m² (interquartile range, 26.8 mL/min/1.73 m²). The patients were divided into 5 groups according to the Kidney Disease: Improving Global Outcomes 2012 guidelines: group 1 with normal or increased GFR (>90 mL/min/1.73 m²); group 2 with mild GFR decrease (60 to 89 mL/min/1.73 m²); group 3a with mild to moderate GFR decrease (45 to 59 mL/min/1.73 m²); group 3b with moderate to severe GFR decrease (30 to 44 mL/min/1.73 m²); and group 4 with severe GFR decrease (<30 mL/min/1.73 m²). Among the 5 groups of patients, serum calcium levels were different (P = .025), whereas 25(OH)D₃ levels were not (P = .36). PTH levels were comparable across groups 1 through 3a, but they were significantly higher in groups 3b and 4 (P<.0001).Conclusion: In our series of PHPT patients, PTH levels did not rise as a result of renal impairment until GFR decreased below 45 mL/min/1.73 m².Abbreviations: 25(OH)D₃ = 25-hydroxyvitamin D₃ CKD-EPI = Chronic Kidney Disease-Epidemiology Collaboration GFR = glomerular filtration rate K/DOQI = National Kidney Foundation Disease Outcomes Quality Initiative KDIGO = Kidney Disease: Improving Global Outcomes MDRD = Modification of Diet in Renal Disease PHPT = primary hyperparathyroidism PTH = parathyroid hormone     

Falsely Elevated Plasma Parathyroid Hormone Level Mimicking Tertiary Hyperparathyroidism

ObjectiveTo report a case of misdiagnosed tertiary hyperparathyroidism attributable to heterophile antibody interference in a parathyroid hormone (PTH) assay.MethodsWe present clinical and laboratory data relative to this case and review the pertinent English-language literature.ResultsA 36-year-old woman with a functioning renal allograft, PTH excess (3, 374 pg/mL) refractory to medical therapy, and a history of renal osteodystrophy presented for consideration of a third parathyroidectomy. Remedial parathyroidectomy was performed. The PTH levels did not decline postoperatively, but the patient developed severe hypocalcemia. Reanalysis of the patient’s serum specimens was performed with (1) addition of heterophile blocking agents to the murine-based immunoassay and (2) use of a different, goat antibody-based immunoassay. The true PTH level was found to be 5 pg/mL with use of both methods.ConclusionPrevious administration of muromonab-CD3 (Orthoclone OKT3) for immunosuppression may have resulted in the development of human antimurine heterophile antibodies, causing a falsely elevated PTH result. (Endocr Pract. 2011;17:e8-e11)     

Characteristics of Ectopic Parathyroid Glands in 145 Cases of Primary Hyperparathyroidism

ObjectiveTo determine the prevalence of primary hyperparathyroidism (PHPT) arising from ectopic parathyroid glands, to analyze the clinical, biochemical, and anatomic characteristics of such cases, and to compare these characteristics with those found in PHPT associated with orthotopic parathyroid glands.MethodsWe conducted a retrospective study of cases of PHPT evaluated and treated at a referral center. Differences between patients with orthotopic and ectopic parathyroid glands were analyzed statistically.ResultsDuring a recent 5-year period at our institution, 145 cases of PHPT were treated operatively by 3 experienced surgeons. An ectopic parathyroid location was detected in 13 cases (9%). Of the 13 ectopic glands, 4 (31%) were at the tracheoesophageal groove, 4 (31%) were intrathymic, 2 (15%) were intrathyroidal, and 1 each was located in the aortopulmonary window, the anterior (nonthymic) mediastinum, and the submaxillary region. Patients with PHPT attributable to ectopic adenomas had significantly higher serum calcium levels (12.6 ± 0.9 mg/ dL versus 11.4 ± 1.2 mg/dL; P = .05) and larger tumors (25 ± 6.1 mm versus 19 ± 7.6 mm; P = .05) than did patients with orthotopic parathyroid glands. Moreover, hyperparathyroidism-related bone disease was significantly more frequent in patients with abnormal ectopic parathyroid glands than in those with orthotopic parathyroid glands (23% versus 1.5%, respectively; P = .04).ConclusionIn 9% of all cases of PHPT in our study, the condition was associated with ectopically located parathyroid glands. Such cases are usually characterized by larger parathyroid glands, higher serum calcium levels, and a higher frequency of severe bone disease. (Endocr Pract. 2010;16:977-981)     

Calcium,Parathyroid Hormone,and Vitamin D in Patients with Primary Hyperparathyroidism: Normograms Developed from 10000 Cases

ObjectiveTo better define the typical and atypical biochemical profiles of patients with surgically proven primary hyperparathyroidism.MethodsIn this single-center, prospectively conducted study of consecutive patients with surgically proven primary hyperparathyroidism over a 7-year period, we analyzed serum calcium, parathyroid hormone, and 25-hydroxyvitamin D concentrations.ResultsA total of 10 000 patients were included, and more than 210 000 calcium, parathyroid hormone, and 25-hydroxyvitamin D values were evaluated. Both calcium and parathyroid hormone levels demonstrated a Gaussian distribution with the average calcium concentration being 10.9 ± 0.6 mg/dL and the average parathyroid hormone concentration being 105.8 ± 48 pg/mL. The average highest calcium and parathyroid hormone concentrations were 11.4 ± 0.7 mg/dL and 115.3 ± 50 pg/mL, respectively. At least 1 calcium value of 11.0 mg/dL was seen in 87% of patients, but only 21% had 1 or more calcium value above 11.5 mg/dL. Only 7% had a single serum calcium level reaching 12.0 mg/dL. Normocalcemic hyperparathyroidism was seen in just under 3% of patients who had identical findings at surgery. An average parathyroid hormone concentration less than 65 pg/mL was seen in 16%, with 10% of patients who had no high parathyroid hormone values. The average 25-hydroxyvitamin D concentration was 22.4 ± 9 ng/mL, with levels decreasing as calcium levels increased (P < .001); 36% had 25-hydroxyvitamin D levels below 20 ng/mL.ConclusionsPatients with PHPT present with a number of distinct biochemical profiles, but as a group, they present with a near-normal Gaussian distribution of both calcium and parathyroid hormone levels. Either serum calcium or parathyroid hormone remained normal in 13% of patients, yet the findings at surgery are similar to those of patients with elevated calcium or parathyroid hormone. Low 25-hydroxyvitamin D is an expected finding in patients with PHPT, decreasing as serum calcium levels increase. (Endocr Pract. 2011;17:384-394)     

Parathyroid Carcinoma: An Experience from the Indian Primary Hyperparathyroidism Registry

ObjectiveTo describe the details of widely invasive parathyroid carcinoma (WIPC) patients admitted in the Endocrinology department of our institute during the last 22 years and to compare their clinical, biochemical, and hormonal profile with minimally invasive parathyroid carcinoma (MIPC) and sporadic parathyroid adenoma patients.MethodsThis is a retrospective analysis of data from the Indian primary hyperparathyroidism registry.ResultsOf the 547 primary hyperparathyroidism patients in the registry, 5 (2 men and 3 women) had WIPC (0.9%) and 7 (1 man and 6 women) had MIPC (1.3%), with median ages of 45 (interquartile range, 41-51) years and 47 (interquartile range, 28-48) years, respectively. Among the patients with WIPC, renal manifestations were present in 5 patients, skeletal manifestations in 4 patients, and palpable neck masses in 4 patients. Three patients had distant metastases and 2 had cervical lymph node involvement. All 5 patients had surgical resection of their cancers, with persistent disease in 4 patients, but all patients died within 2 years after surgery. One patient with MIPC had a palpable parathyroid nodule; none had lymph nodal or distant metastases. None of the patients with MIPC died during the median follow-up of 18 (interquartile range, 12-18) months. Patients with WIPC had significantly higher serum calcium level compared with sporadic parathyroid adenoma patients with skeletal and renal manifestations.ConclusionAccurate histopathologic classification of parathyroid carcinoma is important as WIPC is associated with a more aggressive clinical course and a higher risk of mortality than MIPC.     

Preoperative Calcium and Parathyroid Hormone Values Are Poor Predictors of Gland Volume and Multigland Disease in Primary Hyperparathyroidism: A Review of 2000 Consecutive Patients

ObjectiveCalcium and parathyroid hormone (PTH) values are believed to have a linear relationship in patients with primary hyperparathyroidism and correlate with parathyroid gland size, with higher values predicting single-gland disease. In this modern series, these preoperative values were correlated with operative findings to determine their utility in predicting the gland involvement at parathyroid exploration.MethodsTwo thousand consecutive patients who underwent initial surgery for sporadic primary hyperparathyroidism from 2000 to 2014 were reviewed. All patients underwent a 4-gland exploration. Relationships between preoperative calcium and PTH values with the total gland volume of each patient were examined and stratified using the number of involved glands: single adenoma (SA), double adenoma (DA), and hyperplasia (H).ResultsThere were 1274 (64%) SA, 359 (18%) DA, and 367 (18%) H cases. There was a poor correlation between preoperative calcium and PTH values (R = 0.37) and both poorly correlated with the total gland volume (R < 0.40). Similarly, subgroup analysis using the number of involved glands showed poor correlation. The mean total gland volume was similar among all subgroups (SA = 1.28 cm³, DA = 1.43 cm³, and H = 1.27 cm³; P = .52), implying that individual glands were smaller in multigland disease. SA was found in 271 (53%) of patients with calcium levels of ≤10.5 mg/dL and 122 (78%) with levels of ≥12 mg/dL (P < .001).ConclusionThis is the largest series correlating preoperative calcium and PTH values with operative findings of gland size and number of diseased glands. Although a lower calcium value predicts somewhat more multigland disease, the overall poor correlation should make the parathyroid surgeon aware that gland size and multigland disease cannot be predicted by preoperative laboratory testing.     

The Role of Surgeon-Performed Office and Preincision Ultrasounds in Localization of Parathyroid Adenomas in Primary Hyperparathyroidism

ObjectiveWe studied the use of surgeon-performed office ultrasound (OU) and preincision ultrasound (PIU) in preoperatively localizing parathyroid adenomas in primary hyperparathyroidism (PHPT).MethodsA retrospective chart review was performed for patients with PHPT who underwent parathyroidectomy between 2013 and 2015. The results of OU and PIU were recorded and compared with the final surgical pathology.ResultsOf 348 patients with PHPT, 285 (81.9%) had single-lesion disease, 49 (14.1%) had double-lesion disease, and 14 (4.0%) had multigland disease with 3 or more lesions. For single-lesion disease, the overall sensitivity and specificity of OU to correctly lateralize the lesion were 64.2% and 91.2%, while those of PIU were 89.4% and 93.6%, respectively. The sensitivity and specificity of PIU were comparable to those of 4-dimensional computed tomography (87.1% and 90.7%, respectively) and ^99mTc-sestamibi scintigraphy (70.4% and 95.9%, respectively). While the majority of PIU cases were preceded by other imaging studies, the accuracy in localizing lesions was not largely affected by the presence of prior computed tomography and/or ^99mTc-sestamibi scintigraphy, as opposed to ultrasounds only. For detecting the presence of multigland disease, the sensitivity and specificity of OU were 26% and 92.2%, while those of PIU were 64.3% and 94.7%, respectively.ConclusionSurgeon-performed OU and PIU are valuable tools in preoperatively localizing the parathyroid adenoma in single-lesion disease, while their utility may be limited for double-lesion or multigland disease. PIU in particular yields high accuracy in detecting parathyroid lesions in combination with other imaging modalities.     

Primary Hyperparathyroidism

ObjectiveTo review primary hyperparathyroidism and the key issues that are relevant to the practicing endocrinologist.MethodsThe latest information on the presentation, diagnosis, and traditional and nontraditional aspects of primary hyperparathyroidism is reviewed.ResultsThe diagnosis of primary hyperparathyroidism is straightforward when the traditional hypercalcemic patient is documented to have an elevated parathyroid hormone (PTH) level. Commonly, patients are identified who have normal serum calcium levels but elevated PTH levels in whom no secondary causes for hyperparathyroidism can be confirmed. Traditional target organs of primary hyperparathyroidism—the skeleton and the kidneys—continue to be a focus in the patient evaluation. Bone mineral density shows a typical pattern of involvement with the distal one-third radius being selectively reduced compared with the lumbar spine in which bone mineral density is generally well maintained. Neurocognitive and cardiovascular aspects of primary hyperparathyroidism, while a focus of recent interest, have not been shown to definitively aid in the decision for or against surgery. The recommendation for surgery in primary hyperparathyroidism is based on guidelines that focus on the serum calcium level, renal function, bone mineral density, and age. In patients who do not meet guidelines, a nonsurgical management approach has merit.ConclusionsPrimary hyperparathyroidism is continuing to show changes in its clinical profile, with normocalcemic primary hyperparathyroidism being a topic of great interest. Skeletal and renal features of primary hyperparathyroidism drive, in most cases, the decision to recommend surgery. In patients who do not meet any criteria for surgery, a conservative approach with appropriate monitoring is acceptable. (Endocr Pract. 2012;18:781-790)     

Role of Imaging Tests for Preoperative Location of Pathologic Parathyroid Tissue in Patients with Primary Hyperparathyroidism

Objective: Primary hyperparathyroidism (PHPT) can be cured by parathyroidectomy, and the preoperative location of enlarged pathologic parathyroid glands is determined by imaging studies, especially cervical ultrasonography and scintigraphy scanning. The aim of this retrospective study was to evaluate the use of preoperative cervical ultrasonography and/or parathyroid scintigraphy in locating pathologic parathyroid tissue in a group of patients with PHPT followed in the same endocrine center.Methods: We examined the records of 61 patients who had undergone parathyroidectomy for PHPT following ^99mTc-sestamibi scintigraphy scan and/or cervical ultrasonography. Scintigraphic and ultrasonographic findings were compared to histopathologic results of the surgical specimens.Results: Ultrasonography detected enlarged parathyroid glands in 87% (48/55) of patients with PHPT and ^99mTc-sestamibi scintigraphy in 79% (37/47) of the cases. Ultrasonography was able to correctly predict the surgical findings in 75% (41/55) of patients and scintigraphy in 72% (34/47). Of 7 patients who had negative ultrasonography, scintigraphy correctly predicted the surgical results in 2 (29%). Of 10 patients who had negative scintigraphy, ultrasonography correctly predicted the surgical results in 4 (40%). When we analyzed only patients with solitary eutopic parathyroid adenomas, the predictive positive values of ultrasonography and scintigraphy were 90% and 86%, respectively.Conclusion: Cervical ultrasonography had a higher likelihood of a correct positive test and a greater predictive positive value for solitary adenoma compared to ^99mTc-sestamibi and should be used as the first diagnostic tool for preoperative localization of affected parathyroid glands in PHPT.Abbreviations:Ca = calciumIEDE = Instituto Estadual de Diabetes e Endocrinologia Luiz CapriglionePHPT = primary hyperparathyroidismPTH = parathyroid hormone     

Primary Hyperparathyroidism in the Young: Comparison with Adult Primary Hyperparathyroidism

Objective: Primary hyperparathyroidism (PHPT) is relatively common among adults but rarely encountered in children and adolescents. According to the western literature, young PHPT is different from adult PHPT and is associated with more severe hypercalcemia. PHPT in the adult Indian population is different from its western counterpart. Here we present the clinical, biochemical, and surgical characteristics of young patients with PHPT treated at our tertiary care center.Methods: PHPT patients were divided into adult (≥25 years) and young (<25 years) groups. The clinical, biochemical, hormonal, and histopathologic characteristics and treatment outcomes in the groups were compared.Results: Out of 358 patients, 47 patients were young and 311 patients were adults. The mean ages of the groups were 19 ± 4 and 45 ± 12 years, respectively. The corresponding female-to-male ratios were 1.24:1 and 3.38:1 (P<.05). The nature and frequency of presenting symptoms were comparable between the 2 groups. The most common symptom in young patients with PHPT was bone pain and was not significantly different from adults (57% vs. 61%, respectively). The most common symptom in adult PHPT was fatigue, which was also not significantly different from young patients (63% vs. 53%, respectively), The serum calcium, phosphate, 25-hydroxyvitamin D levels; alkaline phosphatase Z-score; and parathyroid hormone levels were comparable between the 2 groups. Parathyroid adenoma was the most common histopathologic finding, while hyperplasia was rare in both groups.Conclusion: We observed that young PHPT is not markedly different from its adult counterpart in an Indian population.Abbreviations: ALP = alkaline phosphatase; Ca = calcium; Cr = creatinine; iPTH = intact parathyroid hormone; 25(OH)D = 25-hydroxyvitamin D; P = phosphate; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; RR = reference range; ^99mTc sestamibi = technetium sestamibi; USG = ultrasonography     

Associations of Serum Ionized Calcium,Phosphate, and Pth Levels with Parathyroid Scan in Primary Hyperparathyroidism

Objective: To evaluate the relationship between various biochemical parameters in patients with primary hyperparathyroidism (PHPT) with positive and negative technetium-99 sestamibi (Tc) parathyroid scans performed with single-photon emission computed tomography/computed tomography (SPECT/CT).Methods: This retrospective analysis was used to develop a logistic probability model. It included 218 patients with PHPT. The main outcome measures were serum total calcium, ionized calcium, intact parathyroid hormone (PTH), albumin, alkaline phosphatase, phosphate, 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D, 24-h urinary calcium levels, and parathyroid adenoma weight.Results: Individually, using cut-off levels of 6.0 mg/dL for ionized calcium, 3.0 mg/dL for phosphate, and 90 pg/mL for intact PTH, we found that 91.3% (P = .005), 70.7% (P = .004) and 87.90% (P = .023) of the patients had a positive Tc scan with their corresponding strengths of associations in the parentheses. Similar significant associations were sustained in multivariate setting for serum ionized calcium (P = .015), phosphate (P = .016), and intact PTH (P = .028). A logistic probability model was designed to predict the probability of being positive for Tc scan given a set of covariates.Conclusion: There are significant associations between the levels of serum ionized calcium, phosphate, intact PTH, and Tc scan positivity. Further studies with larger patient populations are needed.Abbreviations: BMI = body mass index; CT = computed tomography; CV = coefficient variation; DXA = dual-energy x-ray absorptiometry; MRI = magnetic resonance imaging; PHPT = primary hyperparathyroidism; PPV = positive predictive value; PTH = parathyroid hormone; SPECT = single-photon emission computed tomography; Tc = technetium-99 sestamibi     

Hypocalcaemic Primary Hyperparathyroidism

A patient with many symptoms and signs of primary hyperparathyroidism had hypocalcaemia when first seen. Bone section histology showed osteomalacia and osteitis fibrosa, and the hyperparathyroidism at this stage was considered to be secondary to osteomalacia with postgastrectomy steatorrhoea. On treatment with vitamin D (with disappearance of her bone pains and weakness) she developed hypercalcaemia. She regained her health after removal of a 6-g. parathyroid adenoma. Normal histology was shown in another parathyroid gland.We believe that the initial hypocalcaemia was due to vitamin-D deficiency, which produced ineffective hyperparathyroidism until it was corrected. A review of the few reports of patients with autonomous hyperparathyroidism with steatorrhoea and osteomalacia does not support the argument that these patients had “tertiary” disease. It suggests that most of them, like our patient, had primary hyperparathyroidism.     

Diagnostic Fine-Needle Aspiration Biopsy of an Intrathyroidal Parathyroid Gland and Subsequent Eucalcemia in a Patient with Primary Hyperparathyroidism

ObjectiveTo present the clinical course of a patient with persistent primary hyperparathyroidism (PHPT) whose intrathyroidal parathyroid gland was diagnosed by ultrasound-guided fine-needle aspiration biopsy (FNAB).MethodsWe describe the clinical course and laboratory, radiographic, and microscopic findings of a patient with persistent PHPT due to an intrathyroidal cystic parathyroid gland and review the relevant literature.ResultsA 74-year-old man with PHPT (presenting serum calcium concentration, 16.2 mg/dL; intact parathyroid hormone [PTH] concentration, 341 pg/mL) had surgical excision of the right superior, right inferior, and left inferior parathyroid glands, but the left superior parathyroid gland remained unidentified. Microscopic examination revealed parathyroid hyperplasia. Technetium Tc 99m sestamibi single-photon emission computed tomography imaging showed uptake in 2 foci, 1 on each side of midline in the neck. Reoperation with attention to the left neck failed to locate another parathyroid gland. Neck ultrasonography demonstrated a complex nodule within the right lower lobe of the thyroid. Results from FNAB of the solid component were consistent with parathyroid cells, and cystic fluid PTH concentration was greater than 1800 pg/mL. Nine months later, neck ultrasonography showed a hypoechoic area located posterior to the inferior pole of the right thyroid. The patient remained eucalcemic 16 months postprocedure.ConclusionAutoinfarction of the parathyroid gland and aspiration of cystic fluid may explain resolution of hypercalcemia. Although PHPT due to functioning parathyroid cysts is rare, and PHPT due to cystic parathyroid hyperplasia has been described, this is the first case report of a patient with persistent PHPT due to a functional parathyroid cyst whose diagnosis by FNAB was followed by eucalcemia. (Endocr Pract. 2008;14:80-86)     

Immunoreactive Parathyroid Hormone in Circulation of Man

WE have reported that parathyroid hormone (PTH) is secreted from the parathyroid in vivo as a polypeptide of eighty-four amino-acids, identical to the hormone stored in the glands (molecular weight of 9,500), but that the hormonal polypeptide is cleaved after it enters the general circulation¹. A large hormonal fragment from this cleavage, with a molecular weight of approximately 7,500, has been identified in the circulation. The fragment differs immunologically from the hormone secreted and extracted from the glands¹. To analyse the biological significance of the metabolism of the hormone and the chemical nature and hormonal activity of the large circulating fragment, we have developed radioimmunoassays that specifically measure the amino-terminal (N-assay) and carboxyl-terminal (C-assay) regions of the hormonal molecule. We now report that much higher concentrations of immunoreactive hormone are found in the general circulation by the C-assay than by the N-assay. The studies with the N-assay indicate that the large fragment has lost a portion of the amino-terminal sequence required for biological activity⁹. Since the fragment is present in much higher concentration than native uncleaved hormone, we must conclude that much of the immunoreactive PTH detected in the circulation is biologically inactive.     

Prospects of Parathyroid Hormone in Therapeutic Intervention

International Journal of Peptide Research and Therapeutics - Biologically active peptides and proteins have wide applications as therapeutic agents as well as diagnostics. Parathyroid hormone...