Ionized vs serum calcium in the diagnosis and management of primary hyperparathyroidism: which is superior?

Analytical evaluation of a direct ion-selective-based analyser: Still gaps to close

INTRODUCTION

Discrepancies between electrolyte concentrations determined by blood gas analysers (BGA) and core-lab chemistry analysers may create confusion in clinical practice. This problem is rooted in the different ion-selective electrode (ISE) methodologies that are used. Whilst most available chemistry analysers use indirect ISE, we evaluated the analytical performance of the new automated chemistry analyser Biossays™ E6 (Snibe), equipped with direct ISE, for the determination of sodium (Na+), potassium (K+), chloride (Cl-), ionized calcium (iCa2+) and pH.

MATERIALS AND METHODS

Total precision, estimated deviation and total error were evaluated for all analytes on the E6 analyser. Several patient cohorts were used to perform method comparisons between the E6 and the direct (RP500e BGA) and indirect (Architect c16000 analyser) ISE methods routinely used in the lab. Obtained data were compared against pre-set quality specifications and used for adjustment of the 2 direct ISE methods. For Na+ and iCa2+, agreement with the routinely used protein-corrected Na+ and total calcium (TCa2+) concentrations were assessed respectively.

RESULTS

The analytical performance for the 4 tested electrolytes (Na+, K+, Cl-, iCa2+) and pH were acceptable and within the specified performance specifications. After adjustment of both direct methods, method comparison on an independent patient cohort showed good agreement. For Na+ and iCa2+, a good correlation with the protein corrected Na+ and TCa2+ results was observed.

CONCLUSION

The acceptable analytical performance and ease-of-use of the E6 direct ion selective instrument is making it feasible to optimize electrolyte determinations to direct methodology.

[Primary hyperparathyroidism: From diagnosis to treatment]

Primary hyperparathyroidism (PHPT) is the leading cause of hypercalcemia. It is secondary to hypersecretion of parathyroid hormone (PTH) by the parathyroid glands. Today, PHTP is asymptomatic in 80-90% of cases. Its repercussions are mainly renal (nephrolithiasis, nephrocalcinosis, decline in renal function) and skeletal (osteoporosis, fractures), and should be systematically investigated. Diagnosis is only biological, and in its classic form relies on the association of hypercalcemia, inappropriate PTH (normal or elevated) and hypercalciuria. Diagnosis of normocalcemic forms, where only PTH is elevated, requires elimination of secondary hyperparathyroidism and confirmation of elevated PTH on two consecutive samples, over a 3 to 6 months period. Imaging evaluation, which combines neck ultrasound with scintigraphy or 18F-choline PET/CT, is of interest only if surgery is indicated. Surgical management of the hyperfunctioning parathyroid gland(s) is the only curative treatment for HPTP. Medical management concerns patients for whom surgery is not indicated, who present a surgical contraindication or who refuse surgery. The diagnosis of HPTP warrants contact with an endocrinologist to ensure its management.

Male Lrp5A214V mice maintain high bone mass during dietary calcium restriction by altering the vitamin D endocrine system

Environmental factors and genetic variation individually impact bone. However, it is not clear how these factors interact to influence peak bone mass accrual. Here we tested whether genetically programmed high bone formation driven by missense mutations in the Lrp5 gene (Lrp5A214V) altered the sensitivity of mice to an environment of inadequate dietary calcium (Ca) intake. Weanling male Lrp5A214V mice and wildtype littermates (control) were fed AIN-93G diets with 0.125%, 0.25%, 0.5% (reference, basal), or 1% Ca from weaning until 12 weeks of age (ie, during bone growth). Urinary Ca, serum Ca, Ca regulatory hormones (PTH, 1,25 dihydroxyvitamin D3 (1,25(OH)2D3)), bone parameters (μCT, ash), and renal/intestinal gene expression were analyzed. As expected, low dietary Ca intake negatively impacted bones and Lrp5A214V mice had higher bone mass and ash content. Although bones of Lrp5A214V mice have more matrix to mineralize, their bones were not more susceptible to low dietary Ca intake. In control mice, low dietary Ca intake exerted expected effects on serum Ca (decreased), PTH (increased), and 1,25(OH)2D3 (increased) as well as their downstream actions (ie, reducing urinary Ca, increasing markers of intestinal Ca absorption). In contrast, Lrp5A214V mice had elevated serum Ca with a normal PTH response but a blunted 1,25(OH)2D3 response to low dietary Ca that was reflected in the renal 1,25(OH)2D3 producing/degrading enzymes, Cyp27b1 and Cyp24a1. Despite elevated serum Ca in Lrp5A214V mice, urinary Ca was not elevated. Despite an abnormal serum 1,25(OH)2D3 response to low dietary Ca, intestinal markers of Ca absorption (Trpv6, S100g mRNA) were elevated in Lrp5A214V mice and responded to low Ca intake. Collectively, our data indicate that the Lrp5A214V mutation induces changes in Ca homeostasis that permit mice to retain more Ca and support their high bone mass phenotype.

Association between serum calcium and prognosis in patients with acute ischemic stroke in ICU: analysis of the MIMIC-IV database

BACKGROUND

While serum Ca has proven to be a reliable predictor of mortality across various diseases, its connection with the clinical outcomes of ischemic stroke (IS) remains inconclusive. Our research aimed to explore the relationships between serum total Ca (tCa) and serum ionized Ca (iCa) and mortality among acute IS (AIS) patients.

METHODS

We gathered data from 1773 AIS patients in the Medical Information Mart for Intensive Care Database IV, including baseline demographic data, comorbidities, vital signs, laboratory-based data, and scoring systems. Endpoints for the study encompassed 30-d, 90-d, and 365-d all-cause mortalities. Employing restricted cubic spline Cox regression, we explored potential nonlinear relationships between admission serum iCa and tCa levels and mortality. Participants were categorized into four groups based on serum iCa and tCa quartiles. Multivariable Cox regression analysis was then conducted to evaluate the independent association of iCa and tCa quartiles with all-cause mortality.

RESULTS

The restricted cubic spline revealed a U-shaped association between iCa and 30-d and 90-d mortality (P<0.05), while the relationship between iCa and 365-d mortality was linear (P<0.05). After adjusting for confounders, multivariable Cox analysis demonstrated that the lowest serum iCa level quartile was independently associated with increased risks of 30-d, 90-d, and 365-d mortality. Similarly, the highest serum iCa level quartile was independently associated with increased risks of 30-d and 90-d mortality, but not 365-d mortality. Notably, serum tCa level showed no association with increased risks of 30-d, 90-d, and 365-d mortality.

CONCLUSIONS

Our findings suggest that serum iCa, rather than tCa, is linked to ischemic stroke prognosis. Both high and low serum iCa levels are associated with poor short-term prognosis, while only low serum iCa is associated with poor long-term prognosis in AIS patients.

Metastatic pulmonary calcifications after pediatric liver transplantation

BACKGROUND

Pulmonary calcification (PC) is a rare clinical entity observed following liver transplantation (LT). Most often identified in adults or in patients with concomitant renal failure, PC is rarely reported in children. While the clinical course of PC is largely benign, cases of progressive respiratory failure and death have been reported. Additionally, PC may mimic several other disease processes making diagnosis and management challenging. Currently, little is reported regarding the diagnosis, management, and long-term outcomes of children with PC following LT.

METHODS

We performed a retrospective chart review of patients undergoing LT at our institution between 2006 and 2023. We identified two patients who developed PC following LT. Their diagnosis, clinical course, and long-term outcomes are reported. A literature review of the presentation, diagnosis, management, and outcomes of adult and pediatric patients with PC post-LT was also performed.

CONCLUSIONS

Pulmonary calcifications are a rare but notable complication after pediatric liver transplantation. Our case series adds to the limited literature on this clinical entity in children but also highlights the fact that effective diagnosis and treatment may be safely accomplished without the use of lung biopsy.

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.

Evaluation and Management of Primary Hyperparathyroidism: Summary Statement and Guidelines from the Fifth International Workshop

The last international guidelines on the evaluation and management of primary hyperparathyroidism (PHPT) were published in 2014. Research since that time has led to new insights into epidemiology, pathophysiology, diagnosis, measurements, genetics, outcomes, presentations, new imaging modalities, target and other organ systems, pregnancy, evaluation, and management. Advances in all these areas are demonstrated by the reference list in which the majority of listings were published after the last set of guidelines. It was thus, timely to convene an international group of over 50 experts to review these advances in our knowledge. Four Task Forces considered: 1. Epidemiology, Pathophysiology, and Genetics; 2. Classical and Nonclassical Features; 3. Surgical Aspects; and 4. Management. For Task Force 4 on the Management of PHPT, Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) methodology addressed surgical management of asymptomatic PHPT and non-surgical medical management of PHPT. The findings of this systematic review that applied GRADE methods to randomized trials are published as part of this series. Task Force 4 also reviewed a much larger body of new knowledge from observations studies that did not specifically fit the criteria of GRADE methodology. The full reports of these 4 Task Forces immediately follow this summary statement. Distilling the essence of all deliberations of all Task Force reports and Methodological reviews, we offer, in this summary statement, evidence-based recommendations and guidelines for the evaluation and management of PHPT. Different from the conclusions of the last workshop, these deliberations have led to revisions of renal guidelines and more evidence for the other recommendations. The accompanying papers present an in-depth discussion of topics summarized in this report. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Vitamin A Induced Hypercalcemia in Burn Patients: A Case Study

Vitamin and steroid supplementation such as oxandrolone are commonly given to speed the recovery process in severe burn injuries. Vitamin A is administered concurrently with steroids because of its pro-inflammatory and positive effects on wound healing. However, vitamin A supplementation warrants caution as hypercalcemia can result from vitamin A overdose. Our case involves an 18-year-old male injured in an oil field explosion who presented with 55% total body surface area partial and full thickness burns. Following successful resuscitation, he was given vitamin A, oxandrolone, vitamin C, and zinc sulfate as part of the standard vitamin supplementation. On hospital day 33, serum calcium levels were noted to be elevated and increased to 13 mg/dL a few days later. Parathyroid hormone and vitamin D levels were found to be within normal range, and urine analysis showed normal calcium excretion. Subsequent assessment of vitamin A levels revealed significantly elevated levels at 93 mcg/dL. Vitamin A supplementation was discontinued, and the patient was discharged on hospital day 42. At the one-month follow-up, serum calcium levels were normal, which links the hypercalcemia to vitamin A overdose. This case highlights the importance of considering vitamin A overdose as a cause for asymptomatic hypercalcemia with a normal parathyroid and vitamin D workup. While routine, vitamin A supplementation in burn patients calls for assessment of both serum calcium and vitamin A levels throughout the hospital stay to prevent hypercalcemia and its negative effects.

A Clinical Review of the Psychiatric Sequelae of Primary Hyperparathyroidism

Despite one-quarter of patients with primary hyperparathyroidism (PHPT) experiencing psychiatric symptoms, there remains a dearth of literature regarding the diagnosis and further management of psychiatric sequelae in PHPT. We aim to review the literature pertaining to the epidemiology, disease presentation, pathophysiology, diagnostics, and therapeutics regarding psychiatric sequelae of PHPT with an emphasis on clinical pearls for practicing psychiatrists. A literature search was conducted using the US National Library of Medicine’s PubMed resource using the following keywords in various combinations: primary hyperparathyroidism, neuropsychiatric, calcium, psychosis, mania, depression, catatonia, delirium, parathyroidectomy, and psychotropic medication. We discuss in depth all aspects of the diagnosis and management of psychiatric sequela in PHPT. We have also identified epidemiological trends, discussed the most common clinical presentations, and postulated possible mechanisms for psychiatric symptoms in PHPT. Psychiatrists should maintain diagnostic suspicion for PHPT in older adult female patients presenting with new-onset psychiatric illness. Several mechanisms involving the following may explain the variety of psychiatric symptoms in PHPT: tyrosine hydroxylase, parathyroid hormone, interleukin-6, monoamine oxidase, calcium, and the sodium-potassium adenosine triphosphatase transporter. We recommend psychiatrists take a symptom-oriented approach to management. Treating a patient’s psychosis, mania, depression, catatonia, delirium, or eating disorder pathology via conventional therapeutics seems like a rational approach despite the underlying medical etiology. Only parathyroidectomy has been proven to be definitive in the complete amelioration of psychiatric symptoms.

Comparative prospective study on the presentation of normocalcemic primary hyperparathyroidism. Is it more aggressive than the hypercalcemic form?

BACKGROUND

Some patients with primary hyperparathyroidism (PHPT) have an elevated PTH that does not always correlate with high blood calcium levels. We aimed to compare the clinical presentation between normocalcaemic and hypercalcaemic forms using ionized calcium levels as an inclusion criterion.

METHODS

We included all patients referred for surgery for PHPT between January 2015 and December 2017. Patients were divided into 2 groups (hypercalcaemic (hPHTP)/normocalcaemic (nPHPT)).

RESULTS

104 patients were included.64% of the patients who were initially classified as normocalcaemic had high ionized calcium levels. There were no differences between groups except in terms of bone resorption parameters:patients with hypercalcaemia had higher osteocalcin (37.4vs23.5 ng/mL,P = .02), collagen amino-terminal propeptide (73.5vs49.2 ng/mL,P = .005), and beta-CTX levels (0.68vs0.38 ng/mL,P = .001). Bone involvement as measured by densitometry was similar.

CONCLUSSIONS

When these patients' diagnosis and classification is accurate, their clinical presentation and symptoms are similar to those of the classical form. Since the only difference is in terms of bone resorption parameters, in most cases it seems to be an attenuated form or even similar to the classical presentation. The improvement in diagnostic sensitivity supports the use of ionized calcium levels in patients suspected to have nPHPT.

Surgical Management of Normocalcemic Primary Hyperparathyroidism and the Impact of Intraoperative Parathyroid Hormone Testing on Outcome

Objective To review our surgical experience and the impact of intraoperative parathyroid hormone (IOPTH) testing among patients with normocalcemic primary hyperparathyroidism. Study Design Case series with chart review. Setting Academic referral hospital. Subject and Methods Normocalcemic hyperparathyroidism (NCHPT) patients were identified with normal-range blood ionized calcium and serum elevated parathyroid hormone. Patient demographics, intraoperative findings, IOPTH dynamics, and biochemical outcomes were compared with those of classic primary hyperparathyroidism (PHPT) patients. Results Of the 2120 patients who underwent parathyroidectomy, 616 patients met the inclusion criteria: 119 (19.5%) patients had NCHPT, and 497 (80.5%) had classic PHPT. NCHPT patients had higher rates of multigland hyperplasia as compared with classic PHPT (12% vs 4%, P = .002) and smaller gland size ( P < .001). Of 119 NCHPT patients, 114 (97%) achieved >50% drop in IOPTH intraoperatively, as opposed to 492 (99%) among 497 classic PHPT patients ( P = .014). IOPTH drop >50% had an equivalent positive predictive value for long-term cure in both groups. Conclusions Surgeons treating NCHPT patients should suspect the presence of multigland disease and have a low threshold for converting to bilateral exploration depending on IOPTH decay dynamics.

American Thyroid Association Statement on Postoperative Hypoparathyroidism: Diagnosis, Prevention, and Management in Adults

BACKGROUND

Hypoparathyroidism (hypoPT) is the most common complication following bilateral thyroid operations. Thyroid surgeons must employ strategies for minimizing and preventing post-thyroidectomy hypoPT. The objective of this American Thyroid Association Surgical Affairs Committee Statement is to provide an overview of its diagnosis, prevention, and treatment.

SUMMARY

HypoPT occurs when a low intact parathyroid hormone (PTH) level is accompanied by hypocalcemia. Risk factors for post-thyroidectomy hypoPT include bilateral thyroid operations, autoimmune thyroid disease, central neck dissection, substernal goiter, surgeon inexperience, and malabsorptive conditions. Medical and surgical strategies to minimize perioperative hypoPT include optimizing vitamin D levels, preserving parathyroid blood supply, and autotransplanting ischemic parathyroid glands. Measurement of intraoperative or early postoperative intact PTH levels following thyroidectomy can help guide patient management. In general, a postoperative PTH level <15 pg/mL indicates increased risk for acute hypoPT. Effective management of mild to moderate potential or actual postoperative hypoPT can be achieved by administering either empiric/prophylactic oral calcium and vitamin D, selective oral calcium, and vitamin D based on rapid postoperative PTH level(s), or serial serum calcium levels as a guide. Monitoring for rebound hypercalcemia is necessary to avoid metabolic and renal complications. For more severe hypocalcemia, inpatient management may be necessary. Permanent hypoPT has long-term consequences for both objective and subjective well-being, and should be prevented whenever possible.

Significance of the ionized calcium measurement to assess calcium status in osteopenic/osteoporosis postmenopausal outpatients

INTRODUCTION

Evaluation of calcium status is important in the osteoporotic risk assessment. Although guidelines indicate total calcium (tCa) as first-line measurement, directly measured ionized calcium (m-iCa), considered as the gold standard, is more and more often required. Aim of this study is to evaluate the agreement between m-iCa, tCa and iCa calculated from a formula based on total calcium and albumin (c-iCa) in osteopenic/osteoporotic postmenopausal outpatients.

METHODS

A total of 140 postmenopausal outpatients, 41 osteopenic (OPN) and 99 osteoporotic (OP) were enrolled. Levels of tCa, m-iCa, c-iCa, total protein and albumin, vitamin D (25-OHD), parathyroid hormone 1-84 (PTH), bone alkaline phosphatase, osteocalcin and serum collagen type 1 cross-linked C-telopeptide (CTX) were also measured.

RESULTS

There were no statistically significant differences between OPN and OP groups regarding values of tCa, m-iCa, and c-iCa, 25-OHD and PTH. However, OP women had lower levels of CTX (p < 0.05). A significant direct correlation between m-iCa and tCa (r = 0.60, p < 0.001) and c-iCa (r = 0.61, p < 0.001) was found. Women with isolated hyper-m-iCa had similar DEXA parameter levels respect to the other patients. However, one patient with confirmed primary hyperparathyroidism presented hyper-m-iCa versus normal tCa and c-iCa values.

CONCLUSIONS

The use of tCa could be sufficient to characterize the calcium status in postmenopausal outpatients, but reflexive calcium testing strategy for m-iCa test is necessary to women presenting the low or high extremes of tCa levels, or in women with suspected PHPT.

Expanding the net: The re-evaluation of the multidimensional nomogram calculating the upper limit of normal PTH (maxPTH) in the setting of secondary hyperparathyroidism and the development of the MultIdimensional Predictive hyperparaTHyroid model (Mi-PTH)

BACKGROUND

The multidimensional nomogram calculating the upper limit of normal PTH (maxPTH) model identifies a personalized upper limit of normal parathyroid hormone (PTH) and successfully predicts classical primary hyperparathyroidism (PHP). We aimed to assess whether maxPTH can distinguish normocalcemic PHP (NCPHP) from secondary hyperparathyroidism (SHP), including subjects who underwent bariatric surgery (BrS).

METHODS

A total of 172 subjects with 359 complete datasets of serum calcium (Ca), 25-OH vitamin D, and intact PTH from Oregon were analyzed: 123 subjects (212 datasets) with PHP and 47 (143) with SHP, including 28 (100) with previous BrS. An improved prediction model, MultIdimensional evaluation for Primary hyperparaTHyroidism (Mi-PTH), was created with the same variables as maxPTH by the use of a combined cohort (995 subjects) including participants from previous studies.

RESULTS

In the Oregon cohort, maxPTH's sensitivity was 100% for classical PHP and 89% for NCPHP, but only 50% for normohormonal PHP (NHPHP) and 40% specific for SHP. In comparison, although sensitivity for NCPHP was similar (89%), Mi-PTH vastly improved SHP specificity (85%). In the combined cohort, Mi-PTH had better sensitivity of 98.5% (vs 95%) and specificity 97% (vs 85%).

CONCLUSION

MaxPTH was sensitive in detecting PHP; however, there was low specificity for SHP, especially in patients who underwent BrS. The creation of Mi-PTH provided improved performance measures but requires further prospective evaluation.

Sporadic primary hyperparathyroidism: medical and surgical updates

This review discusses recent findings on the clinical presentation, evaluation, medical and surgical management of primary hyperparathyroidism. Medical management includes the use of cinacalcet and bisphosphonates for bone loss and correction of vitamin D deficiency. Surgical updates reviewed recent studies on the preoperative localization of the disease, specifically, sestamibi scans, 4DCT and MRI. Focused parathyroidectomy continues to be the preferred surgical approach for a select group of patients, guided by intraoperative use of PTH and new technology, such as endoscopic and robotic platforms; however, there appears to be no difference in long-term success compared to the traditional approach.