Clinical Guidelines and PTH Measurement: Does Assay Generation Matter?

Vitamin D assay and supplementation: still debatable issues

Over the last decades, in addition to the improvement of pathophysiological knowledge regarding the role and mechanisms of action of vitamin D, there has been a progressive advancement in analytical technologies for its measurement, as well as in methodological standardization. A significant number of scientific works, meta-analyses, and guidelines have been published on the importance of vitamin D and the need for supplementation in deficient individuals. However, it appears necessary to clarify the fundamental elements related to the measurement of vitamin D (both at the strictly analytical and post-analytical levels) and the scientific evidence related to the efficacy/safety of supplementation. In particular, there is a need to discuss current recommended levels for deficiency, insufficiency and possible toxicity in the light of evidence from standardization projects. Additionally, given the important interrelations between vitamin D, parathyroid hormone (PTH), and fibroblast growth factor-23 (FGF23), the analytical issues and clinical utility of these biomarkers will be discussed.

Chapter 2: Primary Hyperparathyroidism: diagnosis

Primary hyperparathyroidism is now predominantly an asymptomatic pathology, as blood calcium assay has become systematic. Diagnosis therefore requires screening for target organ damage when this is not already indicative of primary hyperparathyroidism. Classical clinical manifestations include bone, kidney and muscle signs, and are characterized by reversibility after parathyroid surgery. Their presence requires blood calcium assay. Non-classical manifestations include cardiovascular, digestive and neuropsychological signs, which are not known to be reversible after surgery. Positive diagnosis is biological, based on a parathyroid hormone value that is inappropriate to the blood calcium value. The typical form combines hypercalcemia, elevated parathyroid hormone and increased calciuria or calcium excretion fraction. Atypical forms combine either hypercalcemia and normal parathyroid hormone level, or normal calcemia with increased parathyroid hormone level, not necessarily secondary to another cause, such as 25(OH) vitamin D deficiency. The oral calcium loading test and the Pro-FHH score are contributive to diagnosis in atypical forms.

Severe Headache and Deterioration of Vision in Left Eye in a Chronic Hemodialysis Patient Revealing a Brown Tumor of Sphenoid Sinus

BACKGROUND/OBJECTIVES

Brown tumors are rare bone lesions associated with hyperparathyroidism, particularly secondary hyperparathyroidism (SHPT), in chronic renal failure. While brown tumors commonly affect bones rich in marrow, the involvement of the sphenoid sinus is extremely rare and can present with neurological symptoms. This study reports a case of a sphenoid sinus brown tumor in a patient on hemodialysis, highlighting its clinical presentation and diagnostic challenges.

METHODS

A 31-year-old woman undergoing chronic hemodialysis presented with a severe headache, diplopia, and progressive vision loss in her left eye. Laboratory tests revealed hypercalcemia, hypophosphatemia, and elevated parathyroid hormone (PTH) levels, consistent with SHPT. The diagnosis was confirmed through a clinical examination and magnetic resonance imaging (MRI).

RESULTS

The clinical examination confirmed decreased visual acuity in the left eye. The laboratory results revealed serum calcium of 15.5 mg/dL, phosphate of 1.0 mg/dL, and PTH of 2000 pg/mL, consistent with SHPT. The imaging studies identified a brown tumor in the sphenoid sinus exerting a mass effect on adjacent structures. This case underscores the rarity of brown tumors in this location, with very few similar reports in the literature.

CONCLUSIONS

Although rare, brown tumors should be considered in patients with SHPT who present with neurological symptoms or cranial lesions. An early diagnosis through biochemical and imaging studies is crucial to prevent severe complications. The management involves treating the underlying hyperparathyroidism, with surgical intervention indicated in cases of neural compression.

Multiple Reaction Monitoring-Mass Spectrometric Immunoassay Analysis of Parathyroid Hormone Fragments with Vitamin D Deficiency in Patients with Diabetes Mellitus

Current immunoassay techniques for analyzing clinically relevant parathyroid hormone (PTH) circulating fragments cannot distinguish microheterogeneity among structurally similar molecular species. This hinders the identification of molecular species and the capture of target analyte information. Since structural modifications are important in disease pathways, mass spectrometry can detect, identify, and quantify heterogeneous ligands captured by antibodies. We aimed to create a sensitive and selective multiple reaction monitoring-mass spectrometric immunoassay analysis (MRM-MSIA)-based method for detecting and quantifying PTH fragments or proteoforms for clinical research. Our study established MRM transitions using triple-quadrupole tandem mass spectrometry for the signature peptides of five PTH fragments. This method was validated according to FDA guidelines, employing the mass spectrometric immunoassay (MSIA) protocol to bolster detection selectivity and sensitivity. This validated approach was applied by analyzing samples from type 2 diabetes mellitus (T2DM) patients with and without vitamin D deficiency. We found serum PTH fragments associated with vitamin D deficiency in patients with and without T2DM. We developed and validated the MRM-MSIA technique specifically designed for the detection and quantification (amino acid (aa38-44), (aa45-51), and (aa65-75)) of these fragments associated with vitamin D deficiency and T2DM. This study is the first to accurately quantify plasma PTH fragments using MRM-MSIA, demonstrating its potential for clinical diagnostics.

Diagnosing Primary Hyperparathyroidism in Pregnancy: A Case of Altered Parathyroid Hormone Degradation in Pregnancy

Diagnosing primary hyperparathyroidism in pregnancy is difficult due to pregnancy-related changes in parathyroid hormone (PTH); calcium; 1,25 vitamin D; and renal calcium excretion. Parathyroid hormone-related peptide (PTHrP) produced by the placenta adds additional complexity. Our case is the first to demonstrate an increased rate of PTH degradation within a pregnant individual who returned unexpectedly low PTH levels. We describe a 27-year-old female patient who presented at 25 weeks gestation with pancreatitis and hypercalcemia. Primary hyperparathyroidism was suspected but variable PTH results led to uncertainty and an assay error was considered. PTH samples were collected in both serum-separating tubes (SST) and EDTA tubes and compared to controls (5 nonpregnant and 5 pregnant individuals). Samples were retested every 2 hours for a period of 10 hours. A rapid decline in the measured PTH was noted in the index case, an observation which differed from controls. We postulated that internal and/or external factors influenced the PTH measurement obtained from our patient. From our observations, rapid PTH degradation in pregnancy, and individual variation in PTH stability and laboratory processes, can influence PTH results and impact on interpreting hypercalcemia in pregnancy.

Normocalcemic primary hyperparathyroidism: From pathophysiology to clinical management

Normocalcemic primary hyperparathyroidism (NPHPT), a variant of primary hyperparathyroidism (PHPT) characterized by persistently elevated parathyroid hormone (PTH) levels and normal serum calcium, has gained recognition as a substantial subset of PHPT cases. Despite its increasing prevalence, the precise pathophysiology and natural progression of NPHPT remain enigmatic. This in-depth literature review explores recent advancements in our understanding of NPHPT, encompassing pathophysiology, clinical presentation, diagnostic approaches, medical and surgical management options. By synthesizing this wealth of information, this review aims to contribute to a more nuanced and informed approach to the treatment of patients grappling with NPHPT. As our understanding of the condition continues to evolve, the knowledge gathered from this review has the potential to significantly enhance the quality of care and outcomes for individuals afflicted with NPHPT, ultimately improving their overall well-being and prognosis.

Liquid chromatography-tandem mass spectrometry in clinical laboratory protein measurement

Proteins are essential components of human cells and tissues, and they are commonly measured in clinical laboratories using immunoassays. However, these assays have certain limitations, such as non-specificity binding, insufficient selectivity, and interference of antibodies. More sensitive, accurate, and efficient technology is required to overcome these limitations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful analytical tool that provides high sensitivity and specificity, making it superior to traditional methods such as biochemical methods and immunoassays. While LC-MS/MS has been increasingly used for detecting small molecular analytes and steroid hormones in clinical practice recently, its application for protein or peptide analysis is still in its early stages. Established methods for quantifying proteins and peptides by LC-MS/MS are mainly focused on scientific research, and only a few proteins and peptides can be or have the potential to be detected and applied in clinical practice. Therefore, this article aims to review the clinical applications, advantages, and challenges of analyzing proteins and peptides using LC-MS/MS in clinical laboratories.

Rare genetic disorders that impair parathyroid hormone synthesis, secretion, or bioactivity provide insights into the diagnostic utility of different parathyroid hormone assays

PURPOSE OF REVIEW

Parathyroid hormone (PTH) is the major peptide hormone regulator of blood calcium homeostasis. Abnormal PTH levels can be observed in patients with various congenital and acquired disorders, including chronic kidney disease (CKD). This review will focus on rare human diseases caused by PTH mutations that have provided insights into the regulation of PTH synthesis and secretion as well as the diagnostic utility of different PTH assays.

RECENT FINDINGS

Over the past years, numerous diseases affecting calcium and phosphate homeostasis have been defined at the molecular level that are responsible for reduced or increased serum PTH levels. The underlying genetic mutations impair parathyroid gland development, involve the PTH gene itself, or alter function of the calcium-sensing receptor (CaSR) or its downstream signaling partners that contribute to regulation of PTH synthesis or secretion. Mutations in the pre sequence of the mature PTH peptide can, for instance, impair hormone synthesis or intracellular processing, while amino acid substitutions affecting the secreted PTH(1-84) impair PTH receptor (PTH1R) activation, or cause defective cleavage of the pro-sequence and thus secretion of a pro- PTH with much reduced biological activity. Mutations affecting the secreted hormone can alter detection by different PTH assays, thus requiring detailed knowledge of the utilized diagnostic test.

SUMMARY

Rare diseases affecting PTH synthesis and secretion have offered helpful insights into parathyroid biology and the diagnostic utility of commonly used PTH assays, which may have implications for the interpretation of PTH measurements in more common disorders such as CKD.

Endocrine Petrified Ear: Associated Endocrine Conditions in Auricular Calcification/Ossification (A Sample-Focused Analysis)

Petrified ear (PE), an exceptional entity, stands for the calcification ± ossification of auricular cartilage (CAC/OAC); its pathogenic traits are still an open matter. Endocrine panel represents one of the most important; yet, no standard protocol of assessments is available. Our objective was to highlight most recent PE data and associated endocrine (versus non-endocrine) ailments in terms of presentation, imagery tools, hormonal assessments, biopsy, outcome, pathogenic features. This was a comprehensive review via PubMed search (January 2000-March 2024). A total of 75 PE subjects included: 46 case reports/series (N = 49) and two imagery-based retrospective studies (N = 26) with CAC/OAC prevalence of 7-23% (N = 251) amid routine head/temporal bone CT scans. Endocrine PE (EPE): N = 23, male/female ratio = 10.5; average age = 56.78, ranges: 22-79; non-EPE cohort: N = 26; male/female ratio = 1.88, mean age = 49.44; ranges: 18-75 (+a single pediatric case).The longest post-diagnosis follow-up was of 6-7 years. The diagnosis of PE and endocrine anomalies was synchronous or not (time gap of 10-20 years). A novel case in point (calcified EPE amid autoimmune poly-endocrine syndrome type 2 with a 10-year post-diagnosis documented follow-up) was introduced. We re-analyzed EPE and re-classified another five subjects as such. Hence, the final EPE cohort (N = 50) showed: adrenal insufficiency was the most frequent endocrine condition (36%) followed by hypopituitarism (22%) and hypothyroidism (18%); 39% of the patients with adrenal failure had Addison's disease; primary type represented 72% of all cases with hypothyroidism; an endocrine autoimmune (any type) component was diagnosed in 18%. We propose the term of "endocrine petrified ear" and a workflow algorithm to assess the potential hormonal/metabolic background in PE.

Primary hyperparathyroidism in adults-(Part I) assessment and medical management: Position statement of the endocrine society of Australia, the Australian & New Zealand endocrine surgeons, and the Australian & New Zealand bone and mineral society

OBJECTIVE

To formulate clinical consensus recommendations on the presentation, assessment, and management of primary hyperparathyroidism (PHPT) in adults.

METHODS

Representatives from relevant Australian and New Zealand Societies used a systematic approach for adaptation of guidelines (ADAPTE) to derive an evidence-informed position statement addressing nine key questions.

RESULTS

PHPT is a biochemical diagnosis. Serum calcium should be measured in patients with suggestive symptoms, reduced bone mineral density or minimal trauma fractures, and in those with renal stones. Other indications are detailed in the manuscript. In patients with hypercalcaemia, intact parathyroid hormone, 25-hydroxy vitamin D, phosphate, and renal function should be measured. In established PHPT, assessment of bone mineral density, vertebral fractures, urinary tract calculi/nephrocalcinosis and quantification of urinary calcium excretion is warranted. Parathyroidectomy is the only definitive treatment and is warranted for all symptomatic patients and should be considered for asymptomatic patients without contraindications to surgery and with >10 years life expectancy. In patients who do not undergo surgery, we recommend annual evaluation for disease progression. Where the diagnosis is not clear or the risk-benefit ratio is not obvious, multidisciplinary discussion and formulation of a consensus management plan is appropriate. Genetic testing for familial hyperparathyroidism is recommended in selected patients.

CONCLUSIONS

These clinical consensus recommendations were developed to provide clinicians with contemporary guidance on the assessment and management of PHPT in adults. It is anticipated that improved health outcomes for individuals and the population will be achieved at a decreased cost to the community.

PHPT with Pancreatitis: Atypical Presentation of PHPT

Background

Primary hyperparathyroidism (PHPT) is rarely associated with the occurrence of acute or chronic pancreatitis, requiring complex perioperative management. This study aimed to assess the prevalence and disease characteristics of pancreatitis in PHPT.

Materials and Methods

This study is a clinicopathological analysis of the medical records of patients who were diagnosed with PHPT with pancreatitis between 1989 and 2021 in the Endocrine Surgery department, SGPGI, Lucknow.

Results

Out of 548 PHPT cases, 44 (8.03%) were found to be associated with pancreatitis. The mean age was 33.57 years (15-65 years); 5 were ≤20 years, while 26 were ≤30 years of age. There were 27 males and 17 females. Twenty-one cases were of acute (11 acute, nine recurrent acute, one acute on chronic), whereas 23 were of chronic pancreatitis (six chronic calcific pancreatitis). The major clinical presentation of PHPT with pancreatitis was abdominal pain (65.91%). The mean number of attacks per patient in recurrent acute pancreatitis was two. Mean PTH levels were 68.19 pmol/L. The mean tumor size (in the largest dimension) was 2.79 ± 1.4 cm while the mean tumor weight was 4.91 g. Nephrolithiasis was associated with 25 cases. An association with multiple endocrine neoplasia type 1 syndrome was seen in one case. The final histopathological diagnosis was parathyroid carcinoma in two, hyperplasia in three, and parathyroid adenoma in 39 cases. Normocalcemia was seen in 27.2%, hypercalcemic crisis in 15.9%, and 25% of patients required semi-emergency parathyroidectomy. The outcome was favorable in all, as none had any further attacks of pancreatitis.

Conclusion

In our study, the prevalence of pancreatitis in PHPT cases was 8.03%. The majority of patients were young. Normocalcemia was seen in 12 patients, so even if calcium levels are normal, PHPT should be suspected in young patients with pancreatitis. Parathyroidectomy resulted in the complete resolution of symptoms of pancreatitis in all 44 patients.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Nutritional secondary hyperparathyroidism in a kitten, supported by immunoenzymatic measurement of feline intact parathyroid hormone

A 6-mo-old, intact male, domestic shorthair cat was referred with a history of poor growth, reluctance to move, and deformation of the nasal profile. The kitten had been fed a diet composed almost exclusively of a complementary pet food and tuna, which was similar to an all-meat diet. We detected osteopenia and hypocalcemia associated with severe parathyroid hormone (PTH) and calcitriol increases; we measured PTH concentrations with an immunoenzymatic method that has been validated in cats. Dietary correction, consisting of a complete and balanced wet pet food formulated for growth, resulted in normalization of calcium and PTH concentrations within 2 mo.

Parathyroid hormone-driven algorithms after thyroid surgery: Not one-size-fits-all

BACKGROUND

Underreported variation in parathyroid hormone (PTH) assays exists. Using quality improvement methods, we aimed to develop an institution-specific PTH-based protocol to predict hypocalcemia after thyroidectomy.

METHODS

We retrospectively reviewed patients who underwent total/completion thyroidectomy. A receiver operating curve (ROC) determined postoperative PTH cut-offs predictive of hypocalcemia. The stakeholders developed PTH-driven calcium management guidelines. Post-implementation outcomes were prospectively measured.

RESULTS

Pre-implementation, 95 patients were assessed. PTH ≤1.5 pmol/L (14.1 pg/ml) predicted hypocalcemia (96%sensitivity), and ≥2.8 pmol/L (26.4 pg/ml) predicted normocalcemia (99%specificity) (area under curve = 0.97, SEM = 0.018). PTH on the day of and morning after surgery were identically predictive. Post-implementation, 64 patients were assessed. Hypocalcemia occurred with PTH >2.8 pmol/L in 2 cases (3.1%). Calcium over-prescribing decreased from 13.7% to 3.1% (p = 0.06). Length of stay (LOS) > 2 nights decreased from 13% to 3.1% (p = 0.05).

CONCLUSION

A PTH-driven calcium management protocol post-thyroidectomy effectively reduces unnecessary calcium replacement and LOS. Given the variability in PTH assays, each institution may need to use individual cut-offs.

The influence of proteoforms: assessing the accuracy of total vitamin D-binding protein quantification by proteolysis and LC-MS/MS

OBJECTIVES

Vitamin D-binding protein (VDBP), a serum transport protein for 25-hydroxyvitamin D [25(OH)D], has three common proteoforms which have co-localized amino acid variations and glycosylation. A monoclonal immunoassay was found to differentially detect VDBP proteoforms and methods using liquid chromatography-tandem mass spectrometry (LC-MS/MS) might be able to overcome this limitation. Previously developed multiple reaction monitoring LC-MS/MS methods for total VDBP quantification represent an opportunity to probe the potential effects of proteoforms on proteolysis, instrument response and quantification accuracy.

METHODS

VDBP was purified from homozygous human donors and quantified using proteolysis or acid hydrolysis and LC-MS/MS. An interlaboratory comparison was performed using pooled human plasma [Standard Reference Material^® 1950 (SRM 1950) Metabolites in Frozen Human Plasma] and analyses with different LC-MS/MS methods in two laboratories.

RESULTS

Several shared peptides from purified proteoforms were found to give reproducible concentrations [≤2.7% coefficient of variation (CV)] and linear instrument responses (R²≥0.9971) when added to human serum. Total VDBP concentrations from proteolysis or amino acid analysis (AAA) of purified proteoforms had ≤1.92% CV. SRM 1950, containing multiple proteoforms, quantified in two laboratories resulted in total VDBP concentrations with 7.05% CV.

CONCLUSIONS

VDBP proteoforms were not found to cause bias during quantification by LC-MS/MS, thus demonstrating that a family of proteins can be accurately quantified using shared peptides. A reference value was assigned for total VDBP in SRM 1950, which may be used to standardize methods and improve the accuracy of VDBP quantification in research and clinical samples.

Utility of Antibodies in the Diagnoses of Thyroid Diseases: A Review Article

Thyroid problems are among the most widespread endocrine illnesses, affecting individuals in India and the global population. A thyroid function test is used to diagnose, screen, and monitor patients. Hyperthyroidism is a clinical condition due to excessive circulation of thyroid hormone; in contrast, hypothyroidism is due to a deficiency of thyroid hormone. Graves' disease (GD) is a form of hyperthyroidism due to thyroid-stimulating hormone receptor autoantibodies (TRAb), and anti-thyroid peroxidase antibodies (anti-TPO antibodies). The most common reason for hypothyroidism is Hashimoto's thyroiditis (HT), in which patients have thyroid receptor antibodies (TRAb), antibodies to thyroid peroxidase (TPO), and thyroglobulin antibodies. Many essential genes, including the thyroid-specific genes thyroglobulin (TSGT), TSH-receptor gene, human leukocyte antigen (HLA) genes, cytotoxic T lymphocyte-associated antigen (CTLA) genes, thyroglobulin gene, vitamin D receptor gene, and many immune-regulatory genes were associated with autoimmune thyroid diseases' (AITDs') etiology. This review paper aims to determine if antibodies are beneficial in detecting autoimmune thyroid disease or not. We have also discussed the etiology of autoimmune thyroid illness, serum antibodies in autoimmune thyroid disease, pathophysiology, and TSH receptor features.

Quantification of Parathyroid Hormone and its Fragments in Serum by Liquid Chromatography-High-Resolution Mass Spectrometry

Parathyroid hormone (PTH), an 84-amino acid peptide hormone, is a major regulator of calcium homeostasis. Quantification of PTH in serum is used clinically to investigate calcium imbalances and for monitoring osteodystrophy in patients with renal failure. In addition to intact PTH, several PTH fragments are found in circulation. Recent studies have shown that accurate quantification of PTH fragments may provide valuable clinical information in certain scenarios. In this chapter, a high-resolution mass spectrometry-based method for quantification of PTH (1-84) and its fragments is described. This method involves immunoaffinity capture of intact PTH and PTH-fragments followed by liquid chromatography-high-resolution mass spectrometry (LC-HRMS).

Menstrual Cycle Related Fluctuations in Circulating Markers of Bone Metabolism at Rest and in Response to Running in Eumenorrheic Females

This study examined potential fluctuations in bone metabolic markers across the menstrual cycle both at rest and after a 30-min bout of continuous running at 80% of V̇O_2max. Resting and post-exercise (0, 30, 90 min) sclerostin, parathyroid hormone (PTH), carboxy-terminal cross-linking telopeptide of type I collagen (β-CTXI), and procollagen type 1 N propeptide (PINP) were assessed in 10 eumenorrheic women (age: 21 ± 3 y, BMI: 23.2 ± 3.0 kg^.m²) during the mid- to late-follicular (FP: day 8.0 ± 1.4) and mid-luteal (LP: day 22.0 ± 2.5) phases of the menstrual cycle. Ovulation was determined using ovulation kits and daily measurement of oral body temperature upon awakening. Menstrual cycle phase was subsequently confirmed by measurement of plasma estradiol and progesterone. On average, resting estradiol concentrations increased from 46.3 ± 8.9 pg·mL^-1 in the FP to 67.3 ± 23.4 pg·mL^-1 in the LP (p = 0.015), and resting progesterone increased from 4.12 ± 2.36 ng·mL^-1 in the FP to 11.86 ± 4.49 ng·mL^-1 in the LP (p < 0.001). At rest, there were no differences between menstrual cycle phases in sclerostin (FP: 260.1 ± 135.0 pg·mL^-1; LP: 303.5 ± 99.9 pg·mL^-1; p = 0.765), PTH (FP: 0.96 ± 0.64 pmol·L^-1; LP: 0.79 ± 0.44 pmol·L^-1; p = 0.568), β-CTXI (FP: 243.1 ± 158.0 ng·L^-1; LP: 202.4 ± 92.3 ng·L^-1; p = 0.198), and PINP (FP: 53.6 ± 8.9 μg·L^-1; LP: 66.2 ± 20.2 μg·L^-1; p = 0.093). Main effects for time (p < 0.05) were shown in sclerostin, PTH, β-CTXI and PINP, without phase or interaction effects. Sclerostin increased from pre- to immediately post-exercise (45%; p = 0.007), and so did PTH (43%; p = 0.011), both returning to resting concentrations 30 min post-exercise. β-CTXI decreased from pre- to post-exercise (20%; p = 0.027) and was still below its pre-exercise concentrations at 90 min post-exercise (17%; p = 0.013). PINP increased immediately post-exercise (29%; p < 0.001), returning to resting concentrations at 30 min post-exercise. These results demonstrate no effect of menstrual cycle phase on resting bone marker concentrations or on the bone metabolic marker response to intense exercise.

Advances in the Progression and Prognosis Biomarkers of Chronic Kidney Disease

Chronic kidney disease (CKD) is one of the increasingly serious public health concerns worldwide; the global burden of CKD is increasingly due to high morbidity and mortality. At present, there are three key problems in the clinical treatment and management of CKD. First, the current diagnostic indicators, such as proteinuria and serum creatinine, are greatly interfered by the physiological conditions of patients, and the changes in the indicator level are not synchronized with renal damage. Second, the established diagnosis of suspected CKD still depends on biopsy, which is not suitable for contraindication patients, is also traumatic, and is not sensitive to early progression. Finally, the prognosis of CKD is affected by many factors; hence, it is ineviatble to develop effective biomarkers to predict CKD prognosis and improve the prognosis through early intervention. Accurate progression monitoring and prognosis improvement of CKD are extremely significant for improving the clinical treatment and management of CKD and reducing the social burden. Therefore, biomarkers reported in recent years, which could play important roles in accurate progression monitoring and prognosis improvement of CKD, were concluded and highlighted in this review article that aims to provide a reference for both the construction of CKD precision therapy system and the pharmaceutical research and development.

Proteoforms and their expanding role in laboratory medicine

The term “proteoforms” describes the range of different structures of a protein product of a single gene, including variations in amino acid sequence and post-translational modifications. This diversity in protein structure contributes to the biological complexity observed in living organisms. As the concentration of a particular proteoform may increase or decrease in abnormal physiological states, proteoforms have long been used in medicine as biomarkers of health and disease. Notably, the analytical approaches used to analyze proteoforms have evolved considerably over the years. While ligand binding methods continue to play a large role in proteoform measurement in the clinical laboratory, unanticipated or unknown post-translational modifications and sequence variants can upend even extensively tested and vetted assays that have successfully made it through the medical regulatory process. As an alternate approach, mass spectrometry—with its high molecular selectivity—has become an essential tool in detection, characterization, and quantification of proteoforms in biological fluids and tissues. This review explores the analytical techniques used for proteoform detection and quantification, with an emphasis on mass spectrometry and its various applications in clinical research and patient care including, revealing new biomarker targets, helping improve the design of contemporary ligand binding in vitro diagnostics, and as mass spectrometric laboratory developed tests used in routine patient care.

Analytical Validation of a New Immunoenzymatic Method for the Measurement of Feline Parathyroid Hormone in Cats with Chronic Kidney Disease

Simple Summary

Parathyroid hormone (PTH) is involved in many metabolic diseases, such as chronic kidney disease (CKD) and calcium disorders, and its measurement could be of clinical utility. However, available methods for the measurement of feline PTH are limited and not widely accessible. The aim of this study was to perform the analytical validation of a new method for PTH measurement in cats. Thirty-eight cats affected with CKD were included. The analytical protocol provided an evaluation of the precision, accuracy, and storage stability at different temperatures. The method investigated showed good precision and accuracy and good stability for 1 week of storage at freezing temperatures. The method was validated in cats, allowing its future use in diagnostic procedures.

Abstract

The determination of parathyroid hormone (PTH) in cats could be of clinical utility in many metabolic disorders, such as renal diseases, hypercalcemia, or nutritional imbalances. However, the available methods for the measurement of feline PTH are limited, not widely available, and need radioimmunoassays. The aim of this study was to perform the analytical validation of a new immunoenzymatic method for the measurement of feline PTH. Thirty-eight cats affected with chronic kidney disease (CKD) were included. PTH was measured using a two-site immunoenzymatic method validated in humans and dogs (ST AIA-PACK^® Intact PTH, Tosoh Bioscience, Tessenderlo, Belgium). The analytical validation provided the evaluation of precision (intra-assay and inter-assay), accuracy (linearity under dilution (LUD) and spike recovery test (SRT)), and the storage stability of serum samples at 20 °C, 4 °C, and −20 °C. The method showed good precision (intra-assay CVs (coefficient of variations) 3.19–9.61%; inter-assay CVs 9.26–15.28%). In both the intra- and inter-assays, the highest imprecision was found with the low concentration pool (9.61% and 15.28%) and accuracy (LUD and SRT r² = 0.99, p < 0.001), while the stability was optimal up until 7 days at −20 °C (−7.7%). The method was successfully validated in cats, allowing its future use in diagnostic procedures.

Population-based pediatric reference values for serum parathyroid hormone, vitamin D, calcium, and phosphate in Danish/North-European white children and adolescents

INTRODUCTION

Parathyroid hormone (PTH) and vitamin D are essential hormones in bone metabolism, especially during pediatric growth. Vitamin D insufficiency is often asymptomatic and is prevalent in high-latitude countries.

METHODS

In a Danish population-based cohort of 2211 6-18-year-olds, sex- and age-specific pediatric reference values for fasting concentrations of intact serum PTH, vitamin D (25-hydroxycholecalciferol, 25-OH-D), total calcium, and phosphate were generated in accordance with Clinical and Laboratory Standards Institute (CLSI) EP28-A3c guidelines. The effect of season on these biomarkers of bone metabolism was evaluated.

RESULTS

In boys, PTH concentrations increased with age, while the vitamin D and phosphate concentrations decreased (all p < .001). In girls, a peak in PTH concentrations and a nadir in vitamin D concentrations were observed in the 10-14-year-olds (both p < .001). Calcium and phosphate decreased with age for both sexes (girls: both p < .001; boys calcium: p < .05, boys phosphate: p < .001). Vitamin D was 20% lower in winter than summer for both sexes (both p < .001). Individuals with vitamin D sufficiency (25-OH-D > 50 nmol/L) exhibited a 5% lower level of PTH compared to the whole sample population (p < .001).

CONCLUSION

The concentrations of PTH, vitamin D, calcium, and phosphate vary during childhood and adolescence, and is dependent on sex and season. These factors should be considered when screening for and treating imbalances in bone metabolism.

Deciphering the Q-markers of nourishing kidney-yin of Cortex Phellodendri amurense from ZhibaiDihuang pill based on Chinmedomics strategy

BACKGROUND

Cortex Phellodendri amurensis (CPA) has high medicinal value in the treatment of kidney-yin deficiency diseases. However, due to the lack of research on the therapeutic material basis of CPA, the current quality control standard for CPA is defective, and the effect of the nourishing kidney-yin of CPA was limited.

PURPOSE

Based on the principle of correspondence between the syndrome and prescriptions, we studied the CPA in ZhibaiDihuang pill (ZBDH) to identify quality markers (Q-markers) of CPA in ZBDH for treating kidney-yin deficiency and seek the potential Q-markers of CPA under nourishing kidney-yin effect combined with the analysis of single CPA.

METHODS

Taking Chinmedomics as the core strategy, metabonomics analysis and effective component identification were performed by UPLC-MS.

RESULTS

A total of 121 chemical components of ZBDH were identified, among which the contents of berberine, palmatine, jatrorrhizine and magnoflorine changed the most obviously with the addition of CPA. Forty-five components were identified in the blood in the markedly effective state, including berberine, palmatine, jatrorrhizine and magnoflorine. The therapeutic material basis of ZBDH in the treatment of kidney-yin deficiency was found, and 6 components were found to derive from CPA, including magnoflorine and jatrorrhizine. In addition, seventeen components were identified in the blood in the single CPA treatment, including berberine, palmatine, jatrorrhizine and magnoflorine.

CONCLUSIONS

Magnoflorine and jatrorrhizine were the Q-markers of CPA for treating kidney-yin deficiency in the formula of ZBDH and they were also potential Q-markers of the nourishing kidney-yin of CPA.

The Association Between Dietary Inflammatory Index and Parathyroid Hormone in Adults With/Without Chronic Kidney Disease

Aims: We aimed to assess the association between dietary inflammation index (DII) with parathyroid hormone (PTH) and hyperparathyroidism (HP) in adults with/without chronic kidney disease (CKD).

Methods: Data were obtained from the 2003–2006 National Health and Nutrition Examination Survey (NHANES). The participants who were <18 years old, pregnant, or missing the data of DII, PTH, and CKD were excluded. DII was calculated based on a 24-h dietary recall interview for each participant. Weighted multivariable regression analysis and subgroup analysis were conducted to estimate the independent relationship between DII with PTH and the HP in the population with CKD/non-CKD.

Results: A total of 7,679 participants were included with the median DII of −0.24 (−2.20 to 1.80) and a mean PTH level of 43.42 ± 23.21 pg/ml. The average PTH was 45.53 ± 26.63 pg/ml for the participants in the highest tertile group compared with 41.42 ± 19.74 pg/ml in the lowest tertile group (P < 0.0001). The rate of HP was 11.15% overall, while the rate in the highest DII tertile was 13.28 and 8.60% in the lowest DII tertile (P < 0.0001). The participants with CKD tended to have higher PTH levels compared with their counterparts (61.23 ± 45.62 vs. 41.80 ± 19.16 pg/ml, P < 0.0001). A positive association between DII scores and PTH was observed (β = 0.46, 95% CI: 0.25, 0.66, P ≤ 0.0001), and higher DII was associated with an increased risk of HP (OR = 1.05, 95% CI: 1.02, 1.08, P = 0.0023). The results from subgroup analysis indicated that this association was similar in the participants with different renal function, gender, age, BMI, hypertension, and diabetes statuses and could also be appropriate for the population with CKD.

Conclusions: Higher consumption of a pro-inflammatory diet appeared to cause a higher PTH level and an increased risk of HP. Anti-inflammatory dietary management may be beneficial to reduce the risk of HP both in the population with and without CKD.

The effect of chronic kidney disease on intraoperative parathyroid hormone: A linear mixed model analysis

BACKGROUND

Reduced creatinine clearance is an indication for surgery in asymptomatic primary hyperparathyroidism, and a significant proportion of patients undergoing parathyroidectomy have chronic kidney disease. The purpose of this study was to evaluate the kinetics of intraoperative parathyroid hormone decline during parathyroidectomy in patients who have chronic kidney disease compared with those with who have normal renal function.

METHODS

This is a single-center, retrospective study of patients with primary hyperparathyroidism undergoing parathyroidectomy (n = 646). Patients were grouped based on estimated glomerular filtration rate greater than (normal renal function) or less than (chronic kidney disease) 60 mL/min/1.73m². All patients had intraoperative parathyroid hormone monitoring and ≥6-month postoperative serum studies to confirm surgical cure. Intraoperative parathyroid hormone kinetic curves were analyzed using a linear mixed model.

RESULTS

Despite similar pre-excision values, patients with chronic kidney disease had significantly higher intraoperative parathyroid hormone values at 5 minutes (76 vs 58 pg/mL, P = .02) and 10 minutes (54 vs 37 pg/mL, P = .004) postexcision. No significant difference was observed in whether patients met Miami criterion by 5 minutes (chronic kidney disease 71%, normal renal function 78%, P = .255) or by 10 minutes (chronic kidney disease 95%, normal renal function 96%, P = .751) postexcision. Using a linear mixed model, glomerular filtration rate did not have a significant effect on the change in intraoperative parathyroid hormone over time.

CONCLUSION

Patients with chronic kidney disease had significantly higher postexcision intraoperative parathyroid hormone levels. However, renal function did not affect the change in intraoperative parathyroid hormone over time, nor did renal function ultimately affect the likelihood of meeting the Miami criterion. Intraoperative parathyroid hormone monitoring remains useful in this population, although additional time points may be needed to observe normalization of values.

Is there a role for bisphosphonates in vascular calcification in chronic kidney disease?

Theoretically bisphosphonates could accelerate or retard vascular calcification. In subjects with low GFR, the position is further confounded by a combination of uncertain pharmacokinetics (GI absorption is poor and inconsistent at all levels of renal function and the effect of low GFR generally is to increase bioavailability) and a highly variable skeletal substrate with extremes of turnover that increase unpredictably further. Although bisphosphonates reduce bone formation by 70-90% in subjects with normal GFR and reduce the ability of bone to buffer exogenous calcium fluxes, in bisphosphonate treated postmenopausal women accelerated vascular calcification has not been documented. The kidneys assist with this buffering, but the capacity to modulate calcium excretion declines as GFR falls, increasing the risk of hypercalcaemia in the event of high calcium influx. In the ESRD patient, decreased buffering capacity substantially increases the risk of transient hypercalcaemia, especially in the setting of dialysis, and as such may promote vascular calcification which is highly prevalent in the CKD population. Low bone turnover may thus be less of a vascular problem in patients with preserved renal function and a bigger problem when the GFR is low. In patients with stage 4 and 5 CKD, adynamic bone disease associates with the severity and progression of arterial calcification, including coronary artery calcification, and further suppression of bone turnover by a bisphosphonate might exacerbate an already high predisposition to vascular calcification. No convincing signal of harm has emerged from clinical studies thus far. For example 51 individuals with CKD stage 3-4 treated with either alendronate 70 mg per week or placebo for 18 months showed no difference in the rate of vascular calcifications. Conversely an observational study of women with stage 3-4 CKD with pre-existing cardiovascular disease found an increased risk of mortality with a hazard ratio of 1.22 (1.04-1.42) in those given bisphosphonates. Direct suppression of vascular calcification by bisphosphonates is probably confined to etidronate - treatment of soft tissue calcification was a recognized indication for this drug and etidronate markedly reduced progression of vascular calcification in CKD patients. Bisphosphonates are analogues of pyrophosphate, a potent calcification inhibitor in bone and soft tissue. Thus the efficacy of etidronate as treatment for soft tissue calcification brought with it a problematic tendency to cause osteomalacia. In contrast, conventional doses of nitrogen-containing bisphosphonates fail to yield circulating concentrations sufficient to exert direct anti-calcifying effects, at least in patients with good renal function and studies using alendronate and ibandronate have yielded inconsistent vascular outcomes.

Analytical and Clinical Validation of a New Immunoenzymatic Method for the Measurement of Canine Parathyroid Hormone

Simple Summary

In dogs affected with chronic kidney disease (CKD), mineral disorders, including renal hyperparathyroidism (RHPT), are frequent. Secondary RHPT is the increase in serum parathyroid hormone (PTH), that can have a significant impact in the disease progression. Despite its clinical utility, the measurement of serum PTH is not routinely executed due to limited availability of validated methods. The aims of this study were: the analytical validation of a new method for PTH measurement in dogs and analysis of the preliminary association of the obtained results with the renal status. Twenty-seven samples obtained from dogs that were healthy or affected with CKD were analysed. PTH was measured using a commercially available human assay. The precision and accuracy of this method were assessed and the PTH stability at different temperatures was evaluated. Clinical validation was performed by comparing PTH values with clinicopathological parameters often altered during CKD, such as creatinine and phosphorus, and with the disease severity. The method showed an optimal precision and accuracy; the stability was compatible with the standard sample processing times. PTH was positively associated with creatinine and phosphorus. The investigated method was successfully validated in dogs, allowing its use for clinical purposes.

Abstract

Renal hyperparathyroidism (RHPT) is one of the main complications in dogs affected with Chronic Kidney Disease (CKD). The measurement of serum parathyroid hormone (PTH) could be of clinical utility for the disease’s treatment and follow-up; however, PTH is not routinely determined due to limited available methods, often not fully validated in dogs. The aims of this study were the analytical validation of an immunoenzymatic method for the measurement of PTH in canine serum and the analysis of preliminary association of the obtained results with renal function. Twenty-six samples obtained from dogs healthy or affected with CKD were analysed. PTH was measured using a two-site immunoenzymometric human assay (ST AIA-PACK^® Intact PTH, Tosoh Bioscience). The analytical validation protocol evaluated the assay precision and accuracy. Also, the PTH’s storage stability at 20 °C, 4 °C and −20 °C was assessed. Clinical validation was performed by comparing PTH values with creatinine, phosphorus and International Renal Interest Society (IRIS) stage. The method showed optimal precision and accuracy, whereas stability was adequate up to 4 h at 20 °C, 24 h at 4 °C and 6 months at −20 °C. PTH was positively associated with creatinine, phosphorus and IRIS stage. The investigated method was thus successfully validated in dogs, allowing its use for clinical purpose.

[Intraoperative measurement of parathyroid hormone in hyperparathyroidism]

Intraoperative parathyroid hormone (IOPTH) determination is based on the short half-life of parathyroid hormone (PTH) and the rapid analytical technology. The IOPTH provides functional information regarding correction of the overproductive state in hyperparathyroidism (HPT) and is superior to macroscopic evaluation of the parathyroid gland (PG) as well as any (intraoperative frozen section) form of histology (so-called biochemical frozen section). In this article the relevance and evaluation of IOPTH is defined for the most important forms of HPT, for primary HPT, renal secondary and tertiary HPT, multiple endocrine neoplasia type 1 (MEN1) and parathyroid carcinoma and clinical scenarios based on the currently available data. It becomes apparent that the additional benefits of IOPTH depend on diverse prerequisites of the specific type of HPT, the diagnostics as well as individual patient factors and strategic considerations for resection. Overall, the costs for IOPTH are comparably low and seem to be justified with respect to the gain in quality. In the hands of specialized endocrine surgeons IOPTH is an essential tool for intraoperative decision-making and quality assurance.

Intraoperative parathyroid hormone (IOPTH) assay might be better than the second-generation assay in parathyroidectomy for primary hyperparathyroidism

BACKGROUND

It is unclear whether the third-generation intraoperative parathyroid hormone assay can improve surgical outcomes over second-generation assay in primary hyperparathyroidism. We aimed to compare the rate of decrease and diagnostic accuracy between the two assays after parathyroid adenoma excision.

METHODS

Consecutive patients undergoing parathyroidectomy with intraoperative parathyroid hormone were analyzed. Blood was drawn before and 10 minutes and 20 minutes after excision of the adenoma. The same blood sample was run simultaneously in the second-generation assays (Elecsys PTH STAT) and third-generation assays (Elecsys 1-84 PTH). Biochemical cure meant >50% intraoperative parathyroid hormone decrease at 10 minutes. Cure meant normocalcemia 6 months after operation.

RESULTS

Relative to the second-generation assay, the value of the intraoperative parathyroid hormone level was less in the third-generation assay before excision (P < .001), at 10 minutes (P < .001), and at 20 minutes (P < .001). The intraoperative parathyroid hormone rate of decrease and the proportion of normalized post-excision intraoperative parathyroid hormone were greater in the third-generation assay (P < .001), but the prediction accuracy appeared similar between the 2 (91.5% vs 91.0%). Patients with worse renal function (estimated glomerular filtration rate <80mL/min/1.73m²) had a slower intraoperative parathyroid hormone decrease in the second-generation but not in the third-generation assay.

CONCLUSION

Despite comparable accuracy between the two generations of assay, the third-generation assay might be better than the second-generation assay because of the more rapid decrease in the intraoperative parathyroid hormone and a greater percentage of normalized intraoperative parathyroid hormone, regardless of baseline renal function.

H-type blood vessels participate in alveolar bone remodeling during murine tooth extraction healing

OBJECTIVES

We aimed to investigate whether skeletal-specific H-type blood vessels exist in alveolar bone and how they function in alveolar bone remodeling.

MATERIALS AND METHODS

H-type vessels with high expression of CD31 and Endomucin (CD31^hi Emcn^hi ) were immunostained in alveolar bone. Abundance and age-related changes in CD31^hi Emcn^hi endothelial cells (H-ECs) were detected by flow cytometry. Osteoprogenitors association with H-type vessels and bone mass were detected in tooth extraction model of alveolar bone remodeling by immunohistofluorescence and micro-CT, respectively. Transcription and expression of H-EC feature genes during in vitro Notch inhibition were measured by RT-qPCR and immunocytofluorescence.

RESULTS

We verified that H-type vessels existed in alveolar bone, the abundance of which was highest at infancy age, then decreased but maintained a constant level during aging. In tooth extraction model, H-ECs significantly increased with concomitant perivascular accumulation of Runx2⁺ osteoprogenitors and gradually augmentation of bone mass. Notch inhibition of in vitro cultured H-ECs resulted in decreased expression levels of Emcn and hes1, but not Pecam1 or Kdr genes, with decreased expression levels of H-EC numbers, accordingly.

CONCLUSIONS

The present study suggests that H-type vessels promote osteogenesis during alveolar bone remodeling. Notch signaling pathway regulates expression of Emcn and possibly determines fate and functions of alveolar H-ECs.

Oxidation of parathyroid hormone

Parathyroid hormone (PTH) is the key hormone regulating calcium homeostasis and, as such, is an important diagnostic and prognostic marker. Although the measurement of PTH has greatly improved over the past few decades, oxidation status thereof is unaccounted for in currently used assays. PTH can be oxidized on methionine residues located at amino acid positions 8 and 18. This is a relevant post-translational modification as, due to refolding of the molecule, it results in the decreased ability to activate the PTH1 receptor. Although this loss of activity after oxidation was observed as early as 1934, only recently a method was developed to measure and distinguish non-oxidized PTH (n-oxPTH) from oxidized PTH. This method creates exciting possibilities for studying more specifically the role of n-oxPTH in physiology and pathology. Therefore, it can now be explored what the clinical implications of measuring n-oxPTH will be. Herein, we review the available evidence of the effect of oxidation on the biological activity of PTH. We also discuss studies examining the mechanism of PTH oxidation in vivo and efforts to stabilize synthetic PTH ex vivo for therapeutic applications. Lastly, the available studies regarding the clinical significance of n-oxPTH are evaluated and future directions discussed.

PTH Derivative promotes wound healing via synergistic multicellular stimulating and exosomal activities

BACKGROUND

Diabetic wounds are a disturbing and rapidly growing clinical problem. A novel peptide, parathyroid hormone related peptide (PTHrP-2), is assumed as multifunctional factor in angiogenesis, fibrogenesis and re-epithelization. This study aims to test PTHrP-2 efficiency and mechanism in wound healing.

METHODS

Through repair phenomenon in vivo some problems were detected, and further research on their mechanisms was made. In vivo therapeutic effects of PTHrP-2 were determined by HE, Masson, microfil and immunohistochemical staining. In vitro direct effects of PTHrP-2 were determined by proliferation, migration, Vascular Endothelial Grown Factor and collagen I secretion of cells and Akt/ Erk1/2 pathway change. In vitro indirect effects of PTHrP-2 was study via exosomes. Exosomes from PTHrP-2 untreated and treated HUVECs and HFF-1 cells were insolated and identified. Exosomes were co-cultured with original cells, HUVECs or HFF-1 cells, and epithelial cells. Proliferation and migration and pathway change were observed. PTHrP-2-HUVEC-Exos were added into in vivo wound to testify its hub role in PTHrP-2 indirect effects in wound healing.

RESULTS

In vivo, PTHrP-2 exerted multifunctional pro-angiogenesis, pro-firbogenesis and re-epithelization effects. In vitro, PTHrP-2 promoted proliferation and migration of endothelial and fibroblast cells, but had no effect on epithelial cells. Therefore, we tested PTHrP-2 indirect effects via exosomes. PTHrP-2 intensified intercellular communication between endothelial cells and fibroblasts and initiated endothelial-epithelial intercellular communication. PTHrP-2-HUVEC-Exos played a hub role in PTHrP-2 indirect effects in wound healing.

CONCLUSION

These findings of this study indicated that PTHrP-2, a multifunctional factor, could promote wound healing via synergistic multicellular stimulating and exosomal activities.

Cardiovascular consequences of parathyroid disorders in adults

PTH is a metabolic active hormone primarily regulating calcium and phosphate homeostasis in a very tight and short term-manner. Parathyroid disorders in adult patients reflect a variety of different conditions related either to the parathyroid glands itself or to the effects of the secreted hormone. The clinical spectrum varies from the common disease primary hyperparathyroidism (PHPT) to the orphan conditions pseudohypoparathyroidism (Ps-HypoPT) and chronic hypoparathyroidism (HypoPT). The purpose of this review is to describe the consequences of disturbances in levels or action of PTH for cardiac function and cardiovascular risk in adult patients with these disorders. Most patients with PHPT achieve the diagnose by chance and have minor or no specific symptoms. Still, these patients with mild PHPT do possess cardiovascular (CV) morbidity, however so far not proven ameliorated by surgery in controlled trials. In severe cases, the CV risk is increased and with a potential reversibility by treatment. Patients with Ps-HypoPT have resistance to PTH action, but not necessarily total resistance in all tissues. So far, no clear CV morbidity or risk has been demonstrated, but there are several aspects of interest for further studies. Most patients with HypoPT do get their hormonal deficiency syndrome following neck surgery. These patients do experience multiple symptoms and do have an increased CV-risk before the primary surgery. Based on existing data, their CV mortality do not deviate from the expected when adjusting for the preexisting increased risk. Patients with nonsurgical (NS-) HypoPT do demonstrate increased CV-risk also associated with exposure time. Endocrine disorders with alterations in PTH function have major impact on the cardiovascular system of importance for morbidity and mortality, wherefore management of these specific diseases should be optimized currently, as new data become available, however also avoiding over-treating asymptomatic patients.

Comparison between Second- and Third-Generation PTH Assays during Minimally Invasive Parathyroidectomy (MIP)

METHODS

112 patients (of which 72.3% females) underwent MIP by the same surgeon. Age, sex, body mass index (BMI), pre- and postoperative serum calcium, creatinine, 25(OH)D levels, PTH at baseline (PTH T0), and PTH at 10 minutes after adenoma resection (PTH T10) were recorded. Both PTH 2G and PTH 3G assays were assessed using the Diasorin assays.

RESULTS

The mean age was 56.1 ± 14.7 years. Mean value of BMI, preoperative calcium, 25(OH)D, and CKD-EPI-eGFR were, respectively, 26.8 ± 4.8 kg/m², 110.9 ± 7.9 mg/L, 19.3 ± 9.2 ng/mL, and 88.6 ± 25.6 mL/min/1.73 m². PTH 2G and PTH 3G assays were well correlated at PTH T0 and PTH T10 (respectively, correlation coefficient 0.74 and 0.72 for intraclass correlation type 3). The median PTH fall was, respectively, of 79.9% and 82.5% for PTH 2G and PTH 3G. Multivariate analysis using the combined PTH 2G and PTH 3G as a dependent variable with 2 repeated measurements (at PTH 0 and PTH 10) showed a significant effect of preoperative calcium on IOPTH fall (p=0.001, effect size 0.13), while no significant effects were observed for sex, age, BMI, and 25(OH)D.

CONCLUSION

PTH 2G and PTH 3G assays resulted in a similar drop in IOPTH values. Elevated preoperative calcium levels are the only independent predictor of IOPTH decline. Further studies are needed to determine other factors that can influence PTH kinetics.

The Interplay Between the Renin-Angiotensin-Aldosterone System and Parathyroid Hormone

The renin-angiotensin-aldosterone system (RAAS) is the regulatory system by which renin induces aldosterone production. Angiotensin II (Ang II) is the main effector substance of the RAAS. The RAAS regulates blood pressure and electrolyte balance by controlling blood volume and peripheral resistance. Excessive activation of the RAAS is an important factor in the onset of cardiovascular disease and the deterioration of this disease. The most common RAAS abnormality is primary aldosteronism (PA). Parathyroid hormone (PTH) is a peptide secreted by the main cells of the parathyroid gland, which promotes elevated blood calcium (Ca²⁺) levels and decreased blood phosphorus (Pi) levels. Excessive secretion of PTH can cause primary hyperparathyroidism (PHPT). Parathyroidism is highly prevalent in postmenopausal women and is often associated with secondary osteoporosis. PA and PHPT are common endocrine system diseases. However, studies have shown a link between the RAAS and PTH, indicating a positive relationship between them. In this review, we explore the complex bidirectional relationship between the RAAS and PTH. We also point out possible future treatment options for related diseases based on this relationship.