Evidence-based cutoffs for total and adjusted calcium: a major factor in detecting severe hypo- and hypercalcemia

OBJECTIVES

Severe hypo- and hypercalcemia are common and urgent treatment is recommended. Free calcium (fCa) is the gold standard but needs blood gas tests with challenging preanalytics. Total calcium (tCa) and calculated adjusted calcium (aCa) are readily available, but their interpretation is hampered by identical tCa and aCa cutoffs, laborious local aCa calculation and difficult comparability of calcium biomarkers.

METHODS

Laboratory results from University Medicine Leipzig were evaluated over a five-year period (236,274 patients). A local aCa equation was derived by linear least squares regression, the agreement between fCa, tCa and aCa assessed with Cohen's κ and decision thresholds derived by this indirect method.

RESULTS

The local aCa equation was created from data of 9,756 patients, each with one paired measurement of tCa, fCa and albumin. Derived aCa cutoffs (1.95/3.15 mmol/L) differ markedly from derived tCa cutoffs (1.6/2.9 mmol/L) and severe hypo- and hypercalcemia can be more accurately assessed by aCa (κ=0.489, 0.812) than by tCa (κ=0.445, 0.744). Comparing our approach to standard care (tCa, literature cutoff), a total 3,250 of 3,680 (88.3 %) misclassified measurements were correctly classified when using aCa with evidence-based cutoffs.

CONCLUSIONS

Optimized cutoffs for aCa and tCa hold great potential for improved patient care. Locally derived aCa equations differ mostly in the chosen mean normal calcium and provide minimal overall improvement, but entail a close examination of the used cutoffs before application.

Twenty-four hour Holter ECG in normocalcemic and hypercalcemic patients with hyperparathyroidism

PURPOSE

To investigate the occurrence of arrhythmias in patients with normocalcemic (NC) primary hyperparathyroidism (PHPT) compared to both hypercalcemic PHPT patients and control subjects by means of 24-h Holter ECG.

METHODS

Thirteen NCPHPT postmenopausal patients were enrolled and age-matched with 13 hypercalcemic PHPT patients and 13 controls. Every subject underwent basal ECG, 24-h Holter ECG and mineral metabolism biochemical evaluation.

RESULTS

PHPT patients had higher mean serum calcium levels compared to both NCPHPT and controls; there was no difference in mean serum calcium levels between NCPHPT and controls. Both NCPHPT and PHPT patients had significantly higher mean PTH levels compared with controls. There were no differences in ECG parameters between the three groups, except for QTc interval. PHPT patients had normal QTc interval values, but significantly shorter mean values compared with those of controls and NCPHPT patients. During 24-h Holter ECG recording, 100% of PHPT patients had supraventricular premature beats (SVPBs), compared to 46% of NCPHPT (p = 0.005) and to 53% of controls (p = 0.01). PHPT patients experienced ventricular premature beats (VPBs) (69.2%) vs 15% of NCPHPT patients (p = 0.01) and 23% of controls (p = 0.04). There was no difference between NCPHPT and controls subjects concerning occurrence of both VPBs and SVPBs.

CONCLUSIONS

NCPHPT patients did not experience an increased occurrence of arrhythmias compared to controls, while PHPT patients showed an increased occurrence compared to both controls and NCPHPT. Our findings are most probably related to the short QTc interval caused by hypercalcemia observed in PHPT patients, but not in NCPHPT.

Discrepancies in corrected calcium versus ionised calcium in a geriatric population: an observational study

BACKGROUND

Calcium can be measured as ionised (Ca-ionised) or albumin-adjusted total calcium (Ca-albumin). Current clinical guidelines predominantly utilise Ca-albumin, despite Ca-ionised being the gold standard. Discrepancies can occur between these measurement modalities and can lead to clinical dilemmas. It remains unclear how large these discrepancies are in older patients. This study investigated the discrepancies between Ca-ionised and Ca-albumin in geriatric patients.

METHODS

This is an observational study of all geriatric patients (n = 876) in the Jeroen Bosch Hospital (January 2018 and January 2021) in whom both Ca-ionised and Ca-albumin were measured. Misclassification of calcaemic state (i.e. low, normal or high) was calculated (percentages), the measure of agreement was described using Cohen's Kappa and for the continuous data Pearson's correlation coefficient was used. Relevant categories of age and renal function were considered for effect modification effects and studied by interaction terms in a regression model.

RESULTS

In one-third of the measurements, there was a misclassification. Ca-albumin measurements failed to identify 28% of hypocalcaemia. In 3.5%, hypercalcemia based on Ca-albumin was not confirmed by Ca-ionised. The correlation coefficient between Ca-ionised and Ca-albumin was 0.743 (P = 0.01) and measure of agreement by Kappa was 0.213 (P < 0.001). In the oldest old (≥ 85 years) and patients with eGFR <30 ml/min/1.73 m2 ,the agreement by Kappa was lower, with values of 0.192 and 0.104, respectively.

CONCLUSION

There is a discrepancy between Ca-albumin and Ca-ionised in one-third of the geriatric patients, leading to clinical dilemmas. In the oldest old and patients with renal dysfunction, this problem is most pronounced.

Testing for Primary Hyperparathyroidism in 17,491 Patients With Hypercalcemia

BACKGROUND

Primary hyperparathyroidism (PHPT) is underdiagnosed and associated with many adverse health effects. Historically, many hypercalcemic patients have not received parathyroid hormone (PTH) testing; however, underlying reasons are uncertain. Our goals are to determine the PTH testing rate among hypercalcemic individuals at a large academic health system and to assess for characteristics associated with testing versus not testing for PHPT to inform future strategies for closing testing gaps.

METHODS

This retrospective study included adult patients with ≥1 elevated serum calcium result between 2018 and 2022. Based on the presence or absence of a serum PTH result, individuals were classified as "screened" versus "unscreened" for PHPT. Demographic and clinical characteristics of these groups were compared.

RESULTS

The sample comprised 17,491 patients: 6567 male (37.5%), 10,924 female (62.5%), mean age 59 y. PTH testing was performed in 6096 (34.9%). Characteristics independently associated with the greatest odds of screening were 5+ elevated calcium results (odds ratio [OR] 5.02, P < 0.0001), chronic kidney disease (OR 3.63, P < 0.0001), maximum calcium >12.0 mg/dL (OR 2.48, P < 0.0001), and osteoporosis (OR 2.42, P < 0.0001). Characteristics associated with lowest odds of screening were age <35 y (OR 0.60, P < 0.0001), death during the study period (OR 0.68, P < 0.0001), age ≥85 y (OR 0.70, P = 0.0007), and depression (OR 0.84; P = 0.0081).

CONCLUSIONS

Only 35% of hypercalcemic patients received PTH testing. Although the presence of PHPT-associated morbidity was generally associated with increased rates of screening, hypercalcemic patients with depression were 16% less likely to be tested.

Too Much of a Good Thing: Severe Hypercalcemia Presenting with Lethargy and Kidney Failure

INTRODUCTION

We present a case of a 58-year-old man with a history of laryngo-pharyngectomy including bilateral thyroidectomy due to hypopharyngeal cancer presenting with lethargy, acute kidney failure, and hypercalcemia. Milk alkali syndrome was diagnosed given the history of high-dose calcium / vitamin D supplementation after ruling out other causes of hypercalcemia. After initial treatment with normal saline, furosemide and denosumab, the patient developed severe symptomatic hypocalcemia as a rare adverse effect of denosumab.

Genetic profile of a large Spanish cohort with hypercalcemia

Introduction

The disorders in the metabolism of calcium can present with manifestations that strongly suggest their diagnosis; however, most of the time, the symptoms with which they are expressed are nonspecific or present only as a laboratory finding, usually hypercalcemia. Because many of these disorders have a genetic etiology, in the present study, we sequenced a selection of 55 genes encoding the principal proteins involved in the regulation of calcium metabolism.

Methods

A cohort of 79 patients with hypercalcemia were analyzed by next-generation sequencing.

Results

The 30% of our cohort presented one pathogenic or likely pathogenic variant in genes associated with hypercalcemia. We confirmed the clinical diagnosis of 17 patients with hypocalciuric hypercalcemia (pathogenic or likely pathogenic variants in the CASR and AP2S1 genes), one patient with neonatal hyperparathyroidism (homozygous pathogenic variant in the CASR gene), and another patient with infantile hypercalcemia (two pathogenic variants in compound heterozygous state in the CYP24A1 gene). However, we also found variants in genes associated with primary hyperparathyroidism (GCM2), renal hypophosphatemia with or without rickets (SLC34A1, SLC34A3, SLC9A3R1, VDR, and CYP27B1), DiGeorge syndrome (TBX1 and NEBL), and hypophosphatasia (ALPL). Our genetic study revealed 11 novel variants.

Conclusions

Our study demonstrates the importance of genetic analysis through massive sequencing to obtain a clinical diagnosis of certainty. The identification of patients with a genetic cause is important for the appropriate treatment and identification of family members at risk of the disease.

[A e-Hypercalcemia]

INTRODUCTION

Hypercalcemia is a common biological abnormality. The etiologies are mainly represented by hyperparathyroidism and neoplastic causes. The other causes, including poisoning, are rare, but should not be neglected.

OBSERVATION

An 82-year-old female patient presented to the emergency room for repeated falls at home, confusion, drowsiness and digestive symptoms. The initial assessment showed hypercalcemia above 3mmol/L. The etiological exploration revealed a very high concentration of 25OH-vitamin D. After repeated interrogations, it appeared that the cause of this intoxication was the intake of a food supplement purchased on the internet, following a prescription from her dentist.

CONCLUSION

Intoxication due to a food supplement containing vitamin D is possible and potentially serious. Raising the awareness of patients and healthcare professionals is necessary in order to prevent this type of poisoning and/or to diagnose it as soon as possible.

Clinical and outcome comparison of genetically positive vs. negative patients in a large cohort of suspected familial hypocalciuric hypercalcemia

OBJECTIVE

Biochemical suspicion of familial hypocalciuric hypercalcemia (FHH) might provide with a negative (FHH-negative) or positive (FHH-positive) genetic result. Understanding the differences between both groups may refine the identification of those with a positive genetic evaluation, aid management decisions and prospective surveillance. We aimed to compare FHH-positive and FHH-negative patients, and to identify predictive variables for FHH-positive cases.

DESIGN

Retrospective, national multi-centre study of patients with suspected FHH and genetic testing of the CASR, AP2S1 and GNA11 genes.

METHODS

Clinical, biochemical, radiological and treatment data were collected. We established a prediction model for the identification of FHH-positive cases by logistic regression analysis and area under the ROC curve (AUROC) was estimated.

RESULTS

We included 66 index cases, of which 30 (45.5%) had a pathogenic variant. FHH-positive cases were younger (p = 0.029), reported more frequently a positive family history (p < 0.001), presented higher magnesium (p < 0.001) and lower parathormone levels (p < 0.001) and were less often treated for hypercalcemia (p = 0.017) in comparison to FHH-negative cases. Magnesium levels showed the highest AUROC (0.825, 95%CI: 0.709-0.941). The multivariate analysis revealed that family history and magnesium levels were independent predictors of a positive genetic result. The predictive model showed an AUROC of 0.909 (95%CI: 0.826-0.991).

CONCLUSIONS

The combination of magnesium and a positive family history offered a good diagnostic accuracy to predict a positive genetic result. Therefore, the inclusion of magnesium measurement in the routine evaluation of patients with suspected FHH might provide insight into the identification of a positive genetic result of any of the CaSR-related genes.

Identification and characterization of a novel CASR mutation causing familial hypocalciuric hypercalcemia

Context

Although a monoallelic mutation in the calcium-sensing receptor (CASR) gene causes familial hypocalciuric hypercalcemia (FHH), the functional characterization of the identified CASR mutation linked to the clinical response to calcimimetics therapy is still limited.

Objective

A 45-year-old male presenting with moderate hypercalcemia, hypocalciuria, and inappropriately high parathyroid hormone (PTH) had a good response to cinacalcet (total serum calcium (Ca2+) from 12.5 to 10.1 mg/dl). We identified the genetic mutation and characterized the functional and pathophysiological mechanisms, and then linked the mutation to calcimimetics treatment in vitro.

Design

Sanger sequencing of the CASR, GNA11, and AP2S1 genes was performed in his family. The simulation model was used to predict the function of the identified mutant. In vitro studies, including immunoblotting, immunofluorescence, a cycloheximide chase study, Calbryte™ 520 Ca2+ detection, and half-maximal effective concentration (EC50), were examined.

Results

This proband was found to carry a de novo heterozygous missense I554N in the cysteine-rich domain of CASR, which was pathogenic based on the different software prediction models and ACGME criteria. The simulation model showed that CASR I554N mutation decreased its binding energy with Ca2+. Human CASR I554N mutation attenuated the stability of CASR protein, reduced the expression of p-ERK 1/2, and blunted the intracellular Ca2+ response to gradient extracellular Ca2+ (eCa2+) concentration. The EC50 study also demonstrated the correctable effect of calcimimetics on the function of the CASR I554N mutation.

Conclusion

This novel CASR I554N mutation causing FHH attenuates CASR stability, its binding affinity with Ca2+, and the response to eCa2+ corrected by therapeutic calcimimetics.

Hypercalcaemia of malignancy: a case of vitamin-D-mediated hypercalcaemia in lymphoma

Hypercalcaemia of malignancy (HCM) is a paraneoplastic syndrome that often portends a poor prognosis. We present an extremely rare (<1%) case of HCM due to extrarenal calcitriol (1,25-(OH)2D) production in a patient with splenic marginal zone lymphoma. A man in his 80s presented with a 3-week history of fatigue, unsteadiness and abdominal pain, and new findings of anaemia, kidney injury and hypercalcaemia. Laboratory evaluation, bone marrow biopsy and positron emission tomography/computed tomography (PET/CT) confirmed the diagnosis of splenic marginal zone lymphoma which produced calcitriol (1,25-(OH)2D3), causing the patient's hypercalcaemia.

[Hypercalcaemia: intensive care or general ward]

Hypercalcaemia is a life-threatening electrolyte imbalance, which not only occurs in the context of an endocrinological disease but is also frequently associated with a tumour. Its severity is determined by the level of deviation from normal, acuity of occurrence, and severity of the symptoms. These are unspecific, can affect any organ system and ultimately result in a life-threatening hypercalcaemic crisis characterised by cardiac arrhythmia, metabolic acidosis, exsiccosis, fever, psychotic states and, ultimately, coma. Endocrinological disorders, drugs such as vitamin D3, vitamin A, checkpoint inhibitors, but also malignancies can be causative for the development of hypercalcaemia. Up to 30% of tumour patients are affected by hypercalcaemia. It is associated with a poor prognosis and a high tumour burden. Malignant hypercalcaemia is mainly caused by PTHrP (parathormone-related peptide), which is secreted by the tumour cells. In oncological patients, serum calcium (ionised calcium and non-ionised calcium) should be evaluated regularly. As the level of serum calcium depends on the albumin concentration, the latter should also be evaluated. Treatment consists of increasing the intravasal volume, increasing calcium excretion and inhibiting calcium reabsorption.

Mucormycosis-induced hypercalcemia: a case report

Hypercalcemia is a vital laboratory marker because it can show underlying severe diseases like cancer and infections. Of all the causes of hypercalcemia, primary hyperparathyroidism, and malignancies are the most common, but granulomatous diseases, such as certain fungal infections, can also be the cause. Here we describe the case of a 29-year-old woman, an insulin-dependent diabetic, found unconscious and tachypneic at home. In the emergency room, the medical team diagnosed diabetic ketoacidosis (DKA) and acute kidney injury (AKI). During hospitalization, despite resolving acidemia, persistent hypercalcemia attracted attention. Laboratory tests showed decreased parathyroid hormone (PTH) levels, confirming non-PTH-dependent hypercalcemia. Computed tomography (CT) of the chest and abdomen demonstrated no alterations, but an upper digestive endoscopy revealed an ulcerated and infiltrative lesion in the stomach. A biopsy showed a granulomatous infiltrate due to mucormycosis infection. The patient received liposomal amphotericin B for 30 days and isavuconazonium for two months. Serum calcium levels improved during treatment. Inquiry of the etiology of hypercalcemia should begin with the PTH assay; high levels are consistent with hyperparathyroidism; low levels, with calcium or vitamin D intoxication, malignancies, prolonged immobilization, and granulomatous diseases. In the latter cases, the overproduction of 1-alpha-hydroxylase by the granulomatous tissue increases the conversion of 25(OH)vitamin D into 1-25(OH)vitamin D, which causes the intestinal absorption of calcium. We have described the first hypercalcemia related to mucormycosis infection in a young diabetic patient, although case presentations associate other fungal infections with elevated serum calcium.

Measurement of plasma total calcium before plasma free ionized calcium - a possibility with affordable pitfalls

Free ionized calcium (fCa) is considered the gold standard for assessing calcium status in patients, but it is relatively expensive and is associated with several preanalytical and analytical error sources. We investigated the feasibility of using a reflex test that involves first measuring total calcium (tCa) and if out of reference range, then measure fCa, with expectation of reducing the number of fCa measurements. We used data from 1815 unique patients with concurrent measurement of fCa, tCa and albumin adjusted calcium (aCa). Patients were stratified by albumin level, and the association of fCa to tCa and aCa respectively was assessed with linear regression. The regression analysis showed the best linearity for tCa and aCa at albumin <35 g/L (R2: 0.80-0.90), and the poorest at albumin >40 g/L (R2: tCa 0.58; aCa 0.59). We examined the accuracy of hypo- and hypercalcemia classifications for tCa, aCa and the reflex test. aCa had more misclassifications of hypo- and hypercalcemia than tCa, with respectively 25% and 21%. Implementation of the reflex test would correct any false hypo- or hypercalcemia classified by tCa, leaving only false negative results corresponding to 9% of all tCa measurements. False negative results were on average 0.04 mmol/L above or below the reference range of fCa. Implementation of the reflex test reduces the number of fCa by 68% without major errors diagnosing hyper- or hypocalcemia.

Ionized hypercalcemia can resolve with nutritional modification in cats with idiopathic hypercalcemia or chronic kidney disease

CASE SERIES SUMMARY

Cats with ionized hypercalcemia that were fed diets with either more than 200 mg calcium per 100 kilocalories (kcal), a calcium:phosphorus (Ca:P) ratio greater than 1.4:1 or both, based on diet history, were included in this case series. Ionized hypercalcemia was documented at least twice in all cats before enrollment. Cats were referred for evaluation of ionized hypercalcemia (n = 5) or were incidentally found to have ionized hypercalcemia (n = 5). After medical workups, cats were diagnosed with either idiopathic hypercalcemia (IHC; n = 7) or chronic kidney disease (n = 3). Cats receiving medications to treat IHC (eg, alendronate, corticosteroids) were excluded. Nutritional recommendations were made to transition the cats to diets with less thn 200 mg calcium per 100 kcal and a Ca:P ratio less than 1.4:1. Ionized calcium (iCa) concentrations were rechecked in all cats, with a median recheck time of 9 weeks (range 3-20). Of the 10 cats, nine (90%) had a decrease in iCa. Of the 10 cats, six (60%) became normocalcemic after the diet change, three (30%) had a partial response and one (10%) did not respond. Of the four cats that did not achieve normocalcemia with a change in diet, two (50%) received chia seeds (1-2 g per day), and at the next recheck, both cats' iCa concentrations had normalized. Three cats had a long-term follow-up. Ionized normocalcemia was maintained for at least two consecutive follow-up visits over a median follow-up period of 33 weeks (range 12-34).

RELEVANCE AND NOVEL INFORMATION

Dietary calcium concentrations and the dietary Ca:P ratio appear to be important variables in considering nutritional approaches for hypercalcemic cats.

Vitamin D Abuse in Pursuit of "Gains" Resulting in Acute Kidney Injury

Vitamin toxicity represents an increasingly frequent clinical diagnosis and can be difficult to initially recognize given the plethora of over-the-counter supplements available. The young, active, and heavily male population of the military is especially susceptible to such supplementation pitfalls. Here we present the case of acute renal failure with hypercalcemia that was found to be secondary to unrecognized high-dose over-the-counter vitamin supplementation and subsequent vitamin D hypervitaminosis initiated by the patient in the hope of boosting testosterone production. This clinical scenario demonstrates the dangers of easily accessible, often seemingly benign supplements and the need for greater education and awareness of supplementation use.

Lithium-associated primary hyperparathyroidism:: An evaluation of screening and referral patterns in a southeastern veteran population

BACKGROUND

Long-term lithium therapy has a well-established but under-recognized association with primary hyperparathyroidism. Rates of hypercalcemia, screening for primary hyperparathyroidism, and referral for parathyroidectomy were evaluated among United States veterans on long-term lithium therapy.

METHODS

Patients undergoing chronic long-term lithium therapy (>12 months) were identified from 1999 to 2022. Demographics, long-term lithium therapy duration, post-treatment calcium, parathyroid hormone, creatinine, and vitamin D levels were abstracted. Rates of screening for hypercalcemia (calcium ≥10.2 mg/dL), primary hyperparathyroidism (parathyroid hormone ≥30 pg/mL in the setting of hypercalcemia), referral for parathyroidectomy, and outcomes were evaluated.

RESULTS

A total of 1,356 patients underwent long-term lithium therapy, 514 of whom received chronic long-term lithium therapy. Baseline characteristics of patients with and without post-treatment hypercalcemia were compared. Of 148 patients with post-treatment hypercalcemia, 112 (74.7%) underwent no further evaluation for primary hyperparathyroidism, while 36 (25.3%) patients had a parathyroid hormone level recorded. Although 33 (91.7%) hypercalcemic patients screened positive for primary hyperparathyroidism, only 5 (13%) were referred for parathyroidectomy. Of the 4 patients who underwent parathyroidectomy, mean calcium was 11.2 mg/dL (range 11.1-11.4), and mean parathyroid hormone was 272 pg/mL (range 108-622). Three patients were localized on preoperative imaging, 2 of whom underwent unilateral exploration with cure, with 1 experiencing recurrence at 31 months. The remaining patient who localized preoperatively underwent bilateral exploration and had 2 ipsilateral glands resected and persistence. The patient who did not localize preoperatively underwent bilateral exploration with 3 gland resection and cure.

CONCLUSIONS

Screening for primary hyperparathyroidism and referral for parathyroidectomy are underutilized in United States veterans undergoing chronic long-term lithium therapy. Institutional protocols to standardize screening, surveillance, and referrals to endocrinology/endocrine surgery could benefit this population at increased risk for primary hyperparathyroidism.

Primary hyperparathyroidism

Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia, is most often identified in postmenopausal women with hypercalcemia and parathyroid hormone (PTH) levels that are either frankly elevated or inappropriately normal. The clinical presentation of PHPT includes three phenotypes: target organ involvement of the renal and skeletal systems; mild asymptomatic hypercalcemia; and more recently, high PTH levels in the context of persistently normal albumin-corrected and ionized serum calcium values. The factors that determine which of these three clinical presentations is more likely to predominate in a given country include the extent to which biochemical screening is employed, the prevalence of vitamin D deficiency, and whether a medical center or practitioner tends to routinely measure PTH levels in the evaluation of low bone density or frank osteoporosis. When biochemical screening is common, asymptomatic primary hyperparathyroidism is the most likely form of the disease. In countries where vitamin D deficiency is prevalent and biochemical screening is not a feature of the health care system, symptomatic disease with skeletal abnormalities is likely to predominate. Finally, when PTH levels are part of the evaluation for low bone mass, the normocalcemic variant is seen. Guidelines for surgical removal of hyperfunctioning parathyroid tissue apply to all three clinical forms of the disease. If guidelines for surgery are not met, parathyroidectomy can also be an appropriate option if there are no medical contraindications to surgery. In settings where either the serum calcium or bone mineral density is of concern, and surgery is not an option, pharmacological approaches are available and effective. Referencing in this article the most current published articles, we review the different presentations of PHPT, with particular emphasis on recent advances in our understanding of target organ involvement and management.

Primary hyperparathyroidism in pregnancy: a case report highlighting uncommon complication

Primary hyperparathyroidism (PHPT) is characterized by elevated levels of calcium and parathyroid hormone (PTH). However, the interpretation of diagnostic tests, such as serum calcium and PTH levels, is complex in pregnant women. The aim of this report is to present a case of PHTP in a pregnant adolescent, with a special emphasis on an uncommon complication, as well as diagnostic and treatment strategies. A 17-year-old pregnant female presented with hyperemesis gravidarum and neurological symptoms, leading to the diagnosis of cerebral venous thrombosis. Further investigations revealed hypercalcemia and persistently elevated PTH levels, consistent with PHPT. After localization studies, the patient underwent an emergency parathyroidectomy with a diagnosis of parathyroid adenoma. During follow-up, intrauterine growth restriction and severe preeclampsia developed, necessitating an emergency cesarean section. Both the mother and neonate had favorable outcomes. PHPT is an infrequent condition in the pregnant population, and its diagnosis can be challenging due to the overlap of symptoms with normal physiological changes during pregnancy. The occurrence of uncommon complications, such as thrombotic phenomena, highlights the need for a comprehensive approach to ensure early detection and management. In most cases, parathyroidectomy is the treatment of choice.

Pneumocystis jirovecii pneumonia presenting with severe, refractory hypercalcaemia in an immunosuppressed renal transplant patient: Review of the literature and novel biochemical insights

Pneumocystis jirovecii pneumonia (PJP) is a rare but serious complication of immunosuppression post-solid organ transplantation. We present a case of refractory, severe hypercalcaemia due to PJP in a renal transplant recipient. Treatment of PJP led to normalisation of the patient's calcium levels, and clinical improvement. To further explore the proposed calcitriol-driven mechanism leading to hypercalcaemia in PJP, we performed biochemical analysis on pre- and post-treatment serum and bronchoalveolar lavage sample at the time of PJP diagnosis. We confirmed high circulating and pulmonary levels of calcitriol in acute, untreated PJP with severe hypercalcaemia. PJP treatment led to reduction of circulating calcitriol to within normal range. We present this case, together with a literature review of similar reported cases, and the novel biochemical evidence supporting extra-renal production of calcitriol by activated pulmonary macrophages as the mechanism underpinning hypercalcaemia in PJP.

IgG4-related disease presenting as severely symptomatic hypercalcemia: A case report and review of literature

Immunoglobulin G4-related disease (IgG4-RD)-associated hypercalcemia has rarely been reported. We report a case of IgG4-RD that presented as severe symptomatic hypercalcemia. A 50-year-old woman with a history of sustained bilateral periorbital swelling and proptosis for more than 5 years presented to our hospital complaining of a 3-day history of significant and progressive nausea, vomiting, loss of appetite, fatigue, and pruritus. She denied a long history of medication. On admission, laboratory tests showed severe hypercalcemia with serum adjusted calcium elevated to 4.34 mmol/L and renal dysfunction with serum creatinine elevated to 206 μmol/L. Urinary calcium excretion was increased. The serum IgG4 subclass was markedly elevated to 22.4 g/L with polyclonal hypergammaglobulinemia. Tests of autoantibodies were all negative. Bone metabolism markers that reflect the activity of osteoblasts and osteoclasts were all significantly elevated. However, the levels of intact parathyroid hormone and 25(OH) vitamin D3 were decreased. B-ultrasonography showed chronic inflammation of bilateral submandibular glands. Neither bone marrow biopsy nor positron emission tomography - computed tomography examination showed evidence of neoplastic diseases. The patient was treated with intravenous saline infusion, loop diuretics, salmon calcitonin, glucocorticoids, and hemodialysis with a good response.

[A case of severe hyperparathyroidism in clinical practice. Case report]

Disorders of the mineral balance often determine the symptoms, the severity of the course and the prognosis of many diseases. Primary hyperparathyroidism (PHPT) is a common endocrine disease caused by increased secretion of parathyroid hormone as a result of primary damage to the parathyroid glands. Diagnosis of PHPT is often difficult. Clinical signs of PHPT appear months or years after the onset of the disease, however, the presence of hypercalcemia serves as an early indication of the disease of the thyroid gland. Often, patients are observed for a long time by related specialists (rheumatologists, traumatologists-orthopedists, oncologists), which gives rise to a lot of problems consisting in the lack of adequate treatment and its result, the progression of the disease, disability, and a decrease in the quality of life. Often, patients are observed for a long time by related specialists (rheumatologists, orthopedic traumatologists, oncologists) under the "masks" of various pathologies (osteoporosis, recurrent urolithiasis, etc.), which gives rise to a lot of problems, consisting in an erroneous diagnosis, lack of adequate treatment and its result, progression of the disease, disability, and a decrease in the quality of life. Late diagnosis of PHPT leads to the development of severe complications (osteoporetic fractures, renal failure) and an increased risk of premature death. A clinical case of late diagnosis of PHPT at the stage of pronounced bone complications of the disease, which proceeded under the guise of osteoarthritis, is considered. According to the results of laboratory and instrumental studies, the following were revealed: hypercalcemia, a significant increase in the concentration of PTH, adenoma of the left lower parathyroid gland, hyperparathyroid osteodystrophy, and a decrease in bone mineral density. Surgical treatment was performed - selective parathyroidectomy with the development of hypocalcemia in the early postoperative period, which was stopped by taking calcium supplements and active vitamin D metabolites and is designed to help practitioners of various specialties to understand the issues of diagnosis of PHPT and effective care for patients.

[New Mutation of CYP24A1 in a Case of Idiopathic Infantile Hypercalcemia Diagnosed in Adulthood]

Mutations in the 24-hydroxylase gene CYP24A1 have been recognized as causes of childhood idiopathic hypercalcemia (IIH), a rare disease (incidence <1:1,000,000 live births) characterized by increased vitamin D sensitivity, with symptomatic severe hypercalcemia. IIH was first described in Great Britain two years after the start of a program of vitamin D supplementation in milk for the prevention of rickets, manifesting in about 200 children with severe hypercalcemia, dehydration, growth failure, weight loss, muscle hypotonia, and nephrocalcinosis. The association between the epidemic occurrence of IIH and vitamin D administration was quickly attributed to intrinsic hypersensitivity to vitamin D, and the pathogenic mechanism was recognized in the inactivation of Cytochrome P450 family 24 subfamily A member 1 (CYP24A1), which was identified as the molecular basis of the pathology. The phenotypic spectrum of CYP24A1 mutation can be variable, manifesting predominantly with childhood onset and severe symptomatology (severe hypercalcemia, growth retardation, lethargy, muscle hypotonia, dehydration), but also with juvenile-adult onset forms with nephrolithiasis, nephrocalcinosis, and alterations in phosphocalcium homeostasis. We describe the case of a patient in whom the diagnosis of IIH was made in adulthood, presenting with finding of nephrocalcinosis in childhood, and with subsequent onset of severe hypercalcemia with hypercalciuria, hypoparathyroidism, hypervitaminosis D, and recurrent renal lithiasis. Genetic investigation revealed the presence in homozygosity of the c_428_430delAAG_p.Glu143del variant in the CYP24A1 gene with autosomal recessive transmission, a mutation not reported in the literature.