Primary hyperparathyroidism caused by a tiny mediastinal parathyroid adenoma with non-localising imaging studies.

Variations in parathyroid gland positions often cause failure in initial parathyroid adenoma surgery, especially when imaging fails to localise the adenoma. This report describes a female patient with primary hyperparathyroidism for which preoperative localisation studies did not determine the position of the hyperfunctioning gland. The initial approach with bilateral cervical exploration and intraoperative parathyroid hormone monitoring was performed unsuccessfully. A mediastinal adenoma was suspected due to meticulous negative neck exploration and repeated negative images for a neck adenoma. Subsequently, a second approach involving mediastinal exploration was performed. After the removal of remnant thymic tissue in the mediastinal space, a significant drop in intraoperative parathyroid hormone levels was achieved. The pathological result confirmed the presence of a tiny pathological parathyroid adenoma within the thymus. At 6 months follow-up, postoperative biochemical assessment was consistent with normal calcium and parathyroid hormone levels.

Role of Postoperative Intact Parathyroid Hormone Levels in Predicting Hypocalcaemia after Thyroidectomy.

OBJECTIVE: To determine the sensitivity and specificity of intact parathyroid hormone (iPTH) levels in predicting hypocalcaemia after thyroidectomy. STUDY DESIGN: A descriptive cross-sectional study. Place and Duration of the Study: Department of General Surgery, Shifa International Hospital and Shifa Foundation, Islamabad, from May 2021 to 2022. METHODOLOGY: The sample size was calculated to be 205 with consecutive non-probability sampling. Serum iPTH levels and serum calcium levels were measured postoperatively at 6 hours and 24 hours and recorded in a proforma for analysis. After collection, the data were entered and analysed using SPSS version 24.0. RESULTS: Among 205 patients, 157 (76.6%) were females and 48 (23.4%) were males. At 6 hours postoperatively, 121 (59%) patients had normal iPTH levels and 123 (60%) patients had normal serum calcium levels (p = 0.15). At 24-hour, 130 (63.4%) patients had normal iPTH levels and 92 (44.9%) patients had normal serum calcium levels (p = 0.001). Overall, 8 (3.9%) patients developed symptomatic hypocalcaemia (p = <0.001). The sensitivity and specificity of iPTH levels at ≤15 pg/ml were 100% and 70%, respectively, but at 24 pg/ml cut-off level, the specificity increased to 90% with sensitivity of 100%. CONCLUSION: Low serum iPTH levels at 6 hours after surgery can predict hypocalcaemia in patients undergoing thyroidectomy, even if serum calcium levels appear normal at that time. KEY WORDS: Parathyroid hormone, Serum calcium, Hypocalcaemia, Total thyroidectomy, Calcium homeostasis.

Induced pluripotent stem cells derived renal tubular cells from a patient with pseudohypoparathyroidism and its response to parathyroid hormone stimulation.

INTRODUCTION: Creating induced pluripotent stem cells (iPSCs) from somatic cells of patients with genetic diseases offers a pathway to generate disease-specific iPSCs carrying genetic markers. Differentiating these iPSCs into renal tubular cells can aid in understanding the pathophysiology of rare inherited renal tubular diseases through cellular experiments. MATERIALS AND METHODS: Two Japanese patients with Pseudohypoparathyroidism (PHP), a 49-year-old woman and a 71-year-old man, were studied. iPSC-derived tubular cells were established from their peripheral blood mononuclear cells (PBMCs). We examined changes in intracellular and extracellular cyclic adenosine monophosphate (cAMP) levels in these cells in response to parathyroid hormone (PTH) stimulation. RESULTS: Renal tubular cells, differentiated from iPSCs of a healthy control (648A1), showed a PTH-dependent increase in both intracellular and extracellular cAMP levels. However, the renal tubular cells derived from the PHP patients' iPSCs showed inconsistent changes in cAMP levels upon PTH exposure. CONCLUSION: We successfully created disease-specific iPSCs from PHP patients' PBMCs, differentiated them into tubular cells, and replicated the distinctive response of the disease to PTH in vitro. This approach could enhance our understanding of the pathophysiology of inherited renal tubular diseases and contribute to developing effective treatments.

Association between blood lead levels and parathyroid hormone among United States adolescents aged 12-19: a cross-sectional study.

Aims: Studies on the association between serum lead levels and parathyroid function in adolescents are lacking. Therefore, in this study, we elucidated the possible association between blood lead levels (BLLs) and the parathyroid hormone (PTH) in adolescents aged 12-19 years in the United States. Methods: In this study, information from the database of the National Health and Nutrition Examination Survey was utilized. The study included 3919 participants from survey cycles between 2003-2004 and 2005-2006. Multivariable linear regression analysis was performed to determine the correlation between BLLs and PTH. Furthermore, smooth curve fitting was utilized to analyze the dose-response relationship between BLLs and PTH. Results: Multivariable linear regression analysis revealed that every 1 µg/dL increase in BLLs was associated with 0.67 pg/mL increase in PTH (ß = 0.67, 95% CI: 0.16-1.18, p < 0.01). However, sex-stratified subgroup analysis revealed that this positive association was only observed in males (ß = 1.16, 95% CI: 0.50-1.83 p < 0.01). Smooth curve fitting revealed a positive correlation between BLLs and PTH. Conclusions: In adolescents in the United States, BLLs are positively correlated with PTH, particularly in males.

Single-cell analysis reveals transcriptional dynamics in healthy primary parathyroid tissue.

Studies on human parathyroids are generally limited to hyperfunctioning glands owing to the difficulty in obtaining normal human tissue. We therefore obtained non-human primate (NHP) parathyroids to provide a suitable alternative for sequencing that would bear a close semblance to human organs. Single-cell RNA expression analysis of parathyroids from four healthy adult M. mulatta reveals a continuous trajectory of epithelial cell states. Pseudotime analysis based on transcriptomic signatures suggests a progression from GCM2 hi progenitors to mature parathyroid hormone (PTH)-expressing epithelial cells with increasing core mitochondrial transcript abundance along pseudotime. We sequenced, as a comparator, four histologically characterized hyperfunctioning human parathyroids with varying oxyphil and chief cell abundance and leveraged advanced computational techniques to highlight similarities and differences from non-human primate parathyroid expression dynamics. Predicted cell-cell communication analysis reveals abundant endothelial cell interactions in the parathyroid cell microenvironment in both human and NHP parathyroid glands. We show abundant RARRES2 transcripts in both human adenoma and normal primate parathyroid cells and use coimmunostaining to reveal high levels of RARRES2 protein (also known as chemerin) in PTH-expressing cells, which could indicate that RARRES2 plays an unrecognized role in parathyroid endocrine function. The data obtained are the first single-cell RNA transcriptome to characterize nondiseased parathyroid cell signatures and to show a transcriptomic progression of cell states within normal parathyroid glands, which can be used to better understand parathyroid cell biology.

No Impairment in Bone Turnover or Executive Functions in Well-Treated Preschoolers with Phenylketonuria-A Pilot Study.

Patients with phenylketonuria (PKU) present signs of impaired executive functioning and bone health in adolescence and adulthood, depending in part on the success of therapy in childhood. Therefore, nine children with well-treated PKU (4-7 years old, 22.2% ♀, seven with a full set of data, two included into partial analysis) and 18 age-, gender- and season-matched controls were analyzed for differences in executive functioning and bone parameters in plasma. Plasma was analyzed with commercially available kits. Cognitive performance in tonic alertness, visuo-spatial working memory, inhibitory control and task switching was assessed by a task battery presented on a touch screen. Regarding cognition, only the performance in incongruent conditions in inhibitory control was significantly better in children with PKU than in controls. No further differences in cognitive tests were detected. Furthermore, no significant difference in the bone turnover markers osteocalcin, undercarboxylated osteocalcin and CTX were detected between children with PKU and controls, while children with PKU had a significantly higher vitamin D concentration (69.44 ± 12.83 nmol/L vs. 41.87 ± 15.99 nmol/L, p < 0.001) and trended towards lower parathyroid hormone concentrations than controls (48.27 ± 15.16 pg/mL vs. 70.61 ± 30.53 pg/mL, p = 0.066). In this small group of well-treated preschoolers with PKU, no impairments in cognitive performance and bone turnover were observed, while vitamin D supplementation of amino acid supplements seems to be sufficient to achieve good vitamin D status.

Trends in using intraoperative parathyroid hormone monitoring during parathyroidectomy: Protocol and rationale for a cross-sectional survey study of North American surgeons.

Hyperparathyroidism is a common endocrine disorder that occurs secondary to abnormal parathyroid gland functioning. Depending on the type of hyperparathyroidism, surgical extirpation of hyperfunctioning parathyroid glands can be considered for disease cure. Intraoperative parathyroid hormone (IOPTH) monitoring improves outcomes in patients undergoing surgery for primary hyperparathyroidism, but studies are needed to characterize its institutional adoption and its role in surgery for secondary and tertiary hyperparathyroidism, as these entities can be difficult to cure. Hence, we will perform a cross-sectional survey study of surgeon rationale, operational details, and barriers associated with IOPTH monitoring adoption across North America. We will utilize a convenience sampling technique to distribute an online survey to head and neck surgeons and endocrine surgeons across North America. This survey will be distributed via email to three North American professional societies (i.e., Canadian Society for Otolaryngologists-Head and Neck Surgeons, American Head and Neck Society, and American Association of Endocrine Surgeons). The survey will consist of 30 multiple choice questions that are divided into three concepts: (1) participant demographics and training details, (2) details of surgical adjuncts during parathyroidectomy, and (3) barriers to adoption of IOPTH. Descriptive analyses and multiple logistic regression will be used to evaluate the impact of demographic, institutional, and training variables on the use of IOPTH monitoring in surgery for all types of hyperparathyroidism and barriers to IOPTH monitoring adoption. Ethics approval was obtained by the Hamilton Integrated Research Ethics Board (2024-17173-GRA). These findings will characterize surgeon and institutional practices with regards to IOPTH monitoring during parathyroid surgery and will inform future trials aimed to optimize the use of IOPTH monitoring in secondary and tertiary hyperparathyroidism.

Association between tobacco smoke exposure and serum parathyroid hormone levels among US adults (NHANES 2003-2006).

Tobacco smoke exposure has been demonstrated to impede bone remodeling and diminish bone density, yet research regarding its correlation with parathyroid hormone (PTH) remains limited. This study aims to investigate the relationship between tobacco smoke exposure and serum PTH levels in adults aged 20 years and older. This study included 7,641 participants from two cycles of the National Health and Nutrition Examination Survey (NHANES, United States, 2003- 2006). Reflect tobacco smoke exposure through serum cotinine levels, and use an adjusted weighted multivariate linear regression model to test the independent linear relationship between serum cotinine and PTH. Stratified analysis was conducted to validate the sensitivity of the conclusions. Smooth curve fitting and threshold effect analysis were performed to assess the non-linear relationship. After comprehensive adjustment using weighted multivariate regression analysis, a negative correlation was found between serum cotinine and PTH levels. The interaction p-values in subgroup analyses were all greater than 0.05. Moreover, smooth curve fitting indicated a non-linear relationship between serum cotinine and PTH, with a turning point observed. Our research indicates that tobacco smoke exposure is negatively correlated and independent of serum parathyroid hormone levels, indicating that long-term tobacco smoke exposure may lead to parathyroid dysfunction in adults.

Alkaline Phosphatase: The Poor Man's iPTH - An Affordable Approach to Bone Health Assessment.

This review delves into relatively less discussed role of alkaline phosphatase (ALP) as an accessible alternative to intact parathyroid hormone (iPTH) in the context of bone health assessment, particularly focussing on its potential boon for underprivileged individuals with chronic kidney disease (CKD) in South Asia. The financial constraints faced by this demographic often hinder regular monitoring of iPTH levels. ALP emerges as a promising surrogate, offering a cost-effective and practical solution for bone health evaluation in resource-constrained settings.

Vitamin D status in female dogs with mammary gland tumors.

BACKGROUND: Little information exists about vitamin D status in bitches with mammary tumors. OBJECTIVES: To determine whether low plasma vitamin D concentrations are found in bitches with mammary tumors. ANIMALS: Eighty-five client-owned bitches with mammary tumors (n = 21 benign, n = 64 malignant) and 39 age-matched healthy bitches. METHODS: Case-control study. Plasma ionized and total calcium, phosphorus, magnesium, urea, creatinine, albumin, total proteins, alanine aminotransferase, alkaline phosphatase, parathyroid hormone (PTH), calcitriol (1,25-dihydroxyvitamin D), and 25-hydroxyvitamin D concentrations were measured in all bitches at the time of clinical diagnosis and before any treatments. Statistical analysis was performed to compare variables among groups (control, benign, and malignant). RESULTS: No significant differences were found when plasma 25-hydroxyvitamin D concentrations in bitches with malignant (148.9 [59.9] ng/mL) and benign mammary tumors (150.1 [122.3] ng/mL) were compared with control group (129.9 [54.5] ng/mL). Parathyroid hormone was significantly higher in bitches with malignant (19.9 [20.5] pg/mL), and benign mammary tumors (14.6 [14.9] pg/mL) compared with control group (7.5 [7.5] pg/mL; P < .01). Only the presence of mammary tumors (P < .01) and age (P = .04; adjusted R2 = .22) was significant in predicting PTH. CONCLUSIONS: Bitches with mammary tumors do not have low 25-hydroxyvitamin D concentrations thus vitamin D supplementation is unlikely to be useful for prevention of mammary tumors in bitches.

Acute pancreatitis and refractory hypercalcemia in the third trimester caused by parathyroid carcinoma.

BACKGROUND: Hypercalcemia can be a rare contributor to acute pancreatitis (AP) in pregnancy. This is primarily due to primary hyperparathyroidism (PHPT), resulting from parathyroid carcinoma. We exhibited a case report to analyze the diagnosis and treatment during the onset of hypercalcemia-induced AP. CASE PRESENTATION: A 32-year-old primigravida presented with acute pancreatitis near full-term gestation. Following a cesarean delivery, there was a reduction in serum amylase and peripancreatic exudate, but her serum calcium concentrations persistently elevated over 4.0 mmol/L. Interventions to lower the hypercalcemia were only temporarily effective, until a high serum parathyroid hormone (PTH) concentration of 1404 pg/mL was detected. Ultrasound revealed a 31 mm × 24 mm hypoechoic oval nodule in the left lower lobe of the thyroid gland. She underwent a parathyroidectomy, resulting in a dramatic decrease in serum PTH level, from preoperative levels of 2051 pg/mL to 299 pg/mL just 20 minutes after removal. Similarly, her serum calcium declined from 3.82 mmol/L to 1.73 mmol/L within 24 hours postoperatively. The final histopathology suggested parathyroid carcinoma. CONCLUSION: When refractory hypercalcemia is present, serum PTH levels should be measured to determine PHPT. Parathyroidectomy is the optimal strategy for alleviating hypercalcemia and clarifying the underlying pathology.

Determination of Reference Intervals of Some Biochemistry Tests by the Bhattacharya and Hoffmann Methods.

BACKGROUND: Clinical laboratory tests are being evaluated with reference intervals (RI). Therefore, it is important that each laboratory determines and classifies its own reliable RI for each test to ensure an accurate and effective interpretation. The proposed method for determining RI is the "direct" approach, but it is a difficult, troublesome, time-consuming, and expensive method. An alternative approach is the "indirect" approach. In this study, we aimed to compare the RI values determined by the indirect method from the Calcium (Ca), Magnesium (Mg), Phosphate (P), 25-Hydroxy Vitamin D (25(OH)D), and Parathyroid hormone (PTH) test results with the RI provided by the manufacturer. METHODS: A total of 1,520,314 Ca, Mg, P, 25(OH)D, and PTH test results, which were studied in our laboratory between January and November 2022, were included in the study. Data cleaning was done for individuals between the ages of 18 - 89, and only one record was allowed. The Tukey method was used to determine and exclude extreme values. Ca and Mg tests were divided into age groups (18 - 59 and 60 - 89 years), P, 25(OH)D, and PTH tests were divided into female - male groups. RI was calculated by using the Bhattacharya and Hoffmann methods. CLIA 19 acceptable limits were used to evaluate the compliance with the manufacturer's RI. RESULTS: The RI results obtained by applying the Bhattacharya and Hoffmann methods were found to be significantly consistent and compatible with each other. According to the manufacturer's RI, Ca and Mg were compatible with RI in both methods, P was considered compatible with PTH and 25(OH)D upper reference limit in the Bhattacharya method, P was considered compatible with 25(OH)D lower reference limit and PTH upper reference limit in the Hoffmann method, while 25(OH)D lower reference limit was found to be different in the Bhattacharya method, and 25(OH)D upper reference limit and PTH lower reference limit were found to be different in the P male group in the Hoffmann method. CONCLUSIONS: We believe that it is of great importance for each laboratory to determine the RI specific for the population they serve and to choose the analytical method they use according to age and gender while periodically updating them to interpret the test results correctly.

Vitamin D3 suppresses Npt2c abundance and differentially modulates phosphate and calcium homeostasis in Npt2a knockout mice.

Vitamin D3 is clinically used for the treatment of vitamin D3 deficiency or osteoporosis, partially because of its role in regulating phosphate (Pi) and calcium (Ca2+) homeostasis. The renal sodium-phosphate cotransporter 2a (Npt2a) plays an important role in Pi homeostasis; however, the role of vitamin D3 in hypophosphatemia has never been investigated. We administered vehicle or vitamin D3 to wild-type (WT) mice or hypophosphatemic Npt2a-/- mice. In contrast to WT mice, vitamin D3 treatment increased plasma Pi levels in Npt2a-/- mice, despite similar levels of reduced parathyroid hormone and increased fibroblast growth factor 23. Plasma Ca2+ was increased ~ twofold in both genotypes. Whereas WT mice were able to increase urinary Pi and Ca2+/creatinine ratios, in Npt2a-/- mice, Pi/creatinine was unchanged and Ca2+/creatinine drastically decreased, coinciding with the highest kidney Ca2+ content, highest plasma creatinine, and greatest amount of nephrocalcinosis. In Npt2a-/- mice, vitamin D3 treatment completely diminished Npt2c abundance, so that mice resembled Npt2a/c double knockout mice. Abundance of intestinal Npt2b and claudin-3 (tight junctions protein) were reduced in Npt2a-/- only, the latter might facilitate the increase in plasma Pi in Npt2a-/- mice. Npt2a might function as regulator between renal Ca2+ excretion and reabsorption in response to vitamin D3.

Parathyroid hormone (1-34) retards the lumbar facet joint degeneration and activates Wnt/ß-catenin signaling pathway in ovariectomized rats.

PURPOSE: Facet joint degeneration (FJD) is a major cause of low back pain. Parathyroid hormone (PTH) (1-34) is commonly used to treat osteoporosis. However, little is known about its effects on FJD induced by estrogen deficiency. This study aims to investigate the effects of PTH (1-34) on FJD induced by estrogen deficiency and the underlying pathogenesis of the disease. METHODS: Forty 3-month-old female Sprague-Dawley rats were randomly divided into four groups: 30 received bilateral ovariectomy (OVX) followed by 12 weeks of treatment with normal saline, PTH (1-34) or 17ß-estradiol (E2), and 10 received sham surgery followed by administration of normal saline. Status and Wnt/ß-catenin signaling activity in the cartilage and subchondral bone of the L4-L5 FJs and serum biomarkers were analyzed. RESULTS: Administration of PTH (1-34) and E2 ameliorated cartilage lesions, and significantly decreased MMP-13 and caspase-3 levels and chondrocyte apoptosis. PTH (1-34) but not E2 significantly increased cartilage thickness, number of chondrocytes, and the expression of aggrecan. PTH (1-34) significantly improved microarchitecture parameters of subchondral bone, increased the expression of collagen I and osteocalcin, and decreased RANKL/OPG ratio. E2 treatment significantly increased the OPG level and decreased the RANKL/OPG ratio in the subchondral bone of ovariectomized rats, but it did not significantly improve the microarchitecture parameters of subchondral bone. Wnt3a and ß-catenin expression was significantly reduced in the articular cartilage and subchondral bone in OVX rats, but PTH (1-34) could increase the expression of these proteins. E2 significantly increased the activity of Wnt/ß-catenin pathway only in cartilage, but not in subchondral bone. The restoration of Wnt/ß-catenin signaling had an obvious correlation with the improvement of some parameters associated with the FJs status. CONCLUSION: Wnt/ß-catenin signaling may be a potential therapeutic target for FJD induced by estrogen deficiency. PTH (1-34) is effective in treating this disease with better efficacy than 17ß-estradiol, and the efficacy may be attributed to its restoration of Wnt/ß-catenin signaling.

Impact of Plant and Animal Protein-Based Meals on Serum Fibroblast Growth Factor-23 Levels in Healthy Young Men: A Randomized Crossover Trial.

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone secreted by osteocytes in response to dietary phosphate intake. An increase in FGF23 level is an indicator of excess phosphate intake relative to the residual nephron number. Therefore, avoiding excessive phosphate intake and inhibiting the elevation of serum FGF23 levels are important to preserve the number of functional nephrons. This randomized crossover trial aimed to determine the potential differences in the impacts on serum FGF23 levels between plant protein and animal protein-based meals in individuals with normal renal function. Nine young men were administered plant (no animal protein) or animal protein-based meals (70% of their protein was from animal sources) with the same phosphate content. The test meals consisted of breakfast, lunch, and dinner. Blood samples were collected in the morning, after overnight fasting, and before and after eating the test meals (for two consecutive days at the same hour each day). Furthermore, a 24-h urine sample was obtained on the day the test meal was consumed. No significant interactions were found among serum phosphate, calcium, and 1,25-dihydroxyvitamin D levels. However, after eating plant protein-based meals, serum FGF23 levels decreased and serum intact parathyroid hormone levels increased (interaction, p<0.05). Additionally, urine 24-h phosphate excretion tended to be lower in individuals consuming plant protein-based meals than in those consuming animal protein-based meals (p=0.06). In individuals with normal renal function, plant protein-based meals may prevent an increase in serum FGF23 levels and kidney damage caused by phosphate loading.

The role of magnesium in the pathogenesis of osteoporosis.

Magnesium (Mg), a nutritional element which is essential for bone development and mineralization, has a role in the progression of osteoporosis. Osteoporosis is a multifactorial disease characterized by significant deterioration of bone microstructure and bone loss. Mg deficiency can affect bone structure in an indirect way through the two main regulators of calcium homeostasis (parathyroid hormone and vitamin D). In human osteoblasts (OBs), parathyroid hormone regulates the expression of receptor activator of nuclear factor-κ B ligand (RANKL) and osteoprotegerin (OPG) to affect osteoclast (OC) formation. In addition, Mg may also affect the vitamin D3 -mediated bone remodeling activity. vitamin D3 usually coordinates the activation of the OB and OC. The unbalanced activation OC leads to bone resorption. The RANK/RANKL/OPG axis is considered to be a key factor in the molecular mechanism of osteoporosis. Mg participates in the pathogenesis of osteoporosis by affecting the regulation of parathyroid hormone and vitamin D levels to affect the RANK/RANKL/OPG axis. Different factors affecting the axis and enhancing OC function led to bone loss and bone tissue microstructure damage, which leads to the occurrence of osteoporosis. Clinical research has shown that Mg supplementation can alleviate the symptoms of osteoporosis to some extent.

Primary Hyperparathyroidism: Part Two: Surgical Management.

Primary hyperparathyroidism (PHPT) is caused by the overproduction of parathyroid hormone by 1 or more parathyroid glands resulting in hypercalcemia and its downstream clinical consequences. The definitive management of PHPT is surgery. Approaches to successful surgery include bilateral exploration or focused parathyroidectomy with intraoperative parathyroid hormone monitoring, which in experienced hands are both associated with a low risk of complications.

Surgical Management of Secondary and Tertiary Hyperparathyroidism.

Secondary hyperparathyroidism (SHPT) often arises from kidney disease and is characterized by elevated parathyroid hormone (PTH) levels. The reported optimal PTH level to balance the compensatory physiologic response in SHPT with the pathologic morbidity and mortality has changed over time with our evolving understanding. Parathyroidectomy for kidney-related hyperparathyroidism requires consideration of the patient's dialysis status, potential for kidney transplantation, and medical history. Extent of parathyroidectomy and intraoperative decision-making requires consideration to maximize cure with the risk of permanent hypoparathyroidism. Parathyroidectomy for kidney-related hyperparathyroidism can provide a reduction in morbidity, mortality, and improved kidney allograft function and survival.

Primary Hyperparathyroidism: Part One: Evaluation.

Primary hyperparathyroidism (PHPT) is a disorder characterized by the autonomous overproduction of parathyroid hormone (PTH) that leads to hypercalcemia, multiple clinical sequelae, and heterogenous presentation. Whether PHPT is caused by a single benign adenoma (85%), multiglandular disease (15%), or parathyroid carcinoma (1%), surgery is the definitive treatment.

Association of defects of enamel with polymorphisms in the vitamin D receptor and parathyroid hormone genes.

This cross-sectional study aimed to investigate the association between developmental defects of enamel (DDE) and single nucleotide polymorphisms (SNPs) in the genes encoding the vitamin D receptor (VDR) and parathyroid hormone (PTH). Orthodontic patients receiving treatment at a dental school were selected through convenience sampling. Intra-oral photographs were used to assess DDE, which were classified according to the criteria proposed by Ghanim et al. (2015) by a single calibrated examiner (Kappa>0.80). Enamel hypoplasia, molar-incisor hypomineralization (MIH), hypomimineralized second primary molar (HSPM), and non-MIH/HSPM demarcated opacities were considered for the analysis. Genomic DNA was extracted from buccal cells. The SNPs in VDR (rs7975232) and PHT (rs694, rs6256, and rs307247) were genotyped using real-time polymerase chain reactions (PCR). Statistical analyses were performed using the PLINK software (version 1.03, designed by Shaun Purcell, EUA). Chi-square or Fisher's exact tests were performed at a significance level of 5%. Ninety-one (n=91) patients (49 females and 42 males) (mean age of 14.1±5.8 years) were included. The frequency of DDE was 38.5% (35 patients). Genotype distributions were in Hardy-Weinberg equilibrium. No significant statistical association was found between DDE and the SNPs evaluated. A borderline association (p=0.09) was observed between DDE and the CC haplotype for SNP rs7975232 in VDR. In conclusion, the selected SNPs in VDR and PTH genes were not associated with DDE in the studied samples.