Asymptomatic and normocalcemic hyperparathyroidism, the silent attack: a combo-endocrinology overview

Primary hyperparathyroidism: from guidelines to outpatient clinic

Primary hyperparathyroidism (PHPT) is a common endocrine disease characterized by hypercalcemia due to inappropriately high parathyroid hormone secretion. While in the typical, symptomatic form of the disease diagnosis is set easily and standard management is surgical removal of the hyperfunctioning parathyroid (HP), this may not be the case in more subtle forms of PHPT, such as the asymptomatic and the normocalcemic PHPT. Localization of the HP could also be challenging, especially in small-sized adenomas, ectopic lesions or multiglandular disease. An experienced surgical team is essential to achieve curative parathyroidectomy. In this article, we used illustrative clinical vignettes to dissect the approach to the patient with PHPT, from the diagnosis establishment to the suggested investigation to identify classical and non-classical PHPT features and the methodology to locate the abnormal tissue. Accordingly, we elaborated on appropriate management, both surgical and conservative.

Calcium/phosphate ratio: an additional tool for the clinical management of asymptomatic primary hyperparathyroidism?

PURPOSE

Serum calcium/phosphate ratio (Ca/P) has been recently proposed as an additional tool to identify primary hyperparathyroidism (PHPT), especially in patients with subclinical presentation, with a proposed cut-off of 3.3 when both values are expressed in mg/dL. No data are available on the relationship between Ca/P and the clinical presentation of PHPT. We thus evaluated this relationship in a large, single-center, unselected series.

METHODS

515 consecutive PHPT patients (mean age 65 ± 13.15 years, 77.1% females) were retrospectively evaluated at diagnosis.

RESULTS

Mean Ca/P was 4.54 ± 1.5 (range 2.36-13.9), being higher than 3.3 in 88.5% of patients. Ca/P was significantly higher in (1) males, (2) symptomatic PHPT, (3) patients with 25-hydroxy vitamin D levels lower than 20 μg/L, (4) patients with osteitis fibrosa cystica, (5) patients with T score < - 2.5 at the radial site. In a multivariate regression analysis, Ca/P resulted significantly associated with PTH levels. After the exclusion of 57 patients with asymptomatic PHPT (aPHPT) patients and serum Ca higher than 1 mg/dL above the upper limit of normal range, no differences were found in Ca/P between aPHPT meeting or not surgical criteria.

CONCLUSIONS

In PHPT Ca/P ratio is associated with increased biochemical and clinical severity of disease and represents a direct indicator of clinical bone damage. However, it does not seem an additional tool to identify aPHPT patients reaching surgical indication.

Primary Hyperparathyroidism in the Common Orthopaedic Practice

An extensive review of the publications on primary hyperparathyroidism (pHPT) is presented in this report. It has strongly been emphasized in the literature that patients with pHPT may present either with the classical symptomatology or with asymptomatic disease, emerged due to biochemical screening. The clinical and epidemiological presentation of pHPT in western countries has changed profoundly during the past few decades, and bone disease is nowadays a distinct rarity. The introduction of serum calcium screening for osteoporosis and the technological advances in the laboratory assessment of parathyroid hormone have played important roles in early diagnosis. Subsequently, the disease is increasingly being detected as asymptomatic hypercalcaemia without guiding signs or symptoms. A third type of disease, the normocalcaemic variant, has been recently described in the literature. However, the potential diagnosis of pHPT should always be on the orthopaedics’ list of differential diagnoses in female or elderly patients with vertebral fractures and nephrolithiasis, either symptomatic or asymptomatic, as well as when solitary or multiple osteolytic lesions are encountered on the radiographs.

Additionally, a middle aged woman with parathyroid adenoma and subsequent brown tumors detected on the pelvic radiographs is reported. Her initial laboratory findings indicated a minimal increase of the serum calcium, a mild increase of the erythrocyte sedimentation rate, and a significant increase in total serum alkaline phosphatase. Finally, the detection of elevated parathyroid hormone levels indicated the diagnosis of pHPT and necessitated imaging studies of the parathyroid glands, which indicated a parathyroid adenoma. Following successful excision of the parathyroid adenoma, the patient suffered from the hungry bone syndrome. After a follow-up of 20 years, the patient had normal calcium, vitamin D, and parathyroid hormone serum levels, while a pelvic radiograph indicated no significant changes in the appearance of the brown tumors.

Primary Hyperparathyroidism in the Common Orthopaedic Practice

An extensive review of the publications on primary hyperparathyroidism (pHPT) is presented in this report. It has strongly been emphasized in the literature that patients with pHPT may present either with the classical symptomatology or with asymptomatic disease, emerged due to biochemical screening. The clinical and epidemiological presentation of pHPT in western countries has changed profoundly during the past few decades, and bone disease is nowadays a distinct rarity. The introduction of serum calcium screening for osteoporosis and the technological advances in the laboratory assessment of parathyroid hormone have played important roles in early diagnosis. Subsequently, the disease is increasingly being detected as asymptomatic hypercalcaemia without guiding signs or symptoms. A third type of disease, the normocalcaemic variant, has been recently described in the literature. However, the potential diagnosis of pHPT should always be on the orthopaedics’ list of differential diagnoses in female or elderly patients with vertebral fractures and nephrolithiasis, either symptomatic or asymptomatic, as well as when solitary or multiple osteolytic lesions are encountered on the radiographs.

Additionally, a middle aged woman with parathyroid adenoma and subsequent brown tumors detected on the pelvic radiographs is reported. Her initial laboratory findings indicated a minimal increase of the serum calcium, a mild increase of the erythrocyte sedimentation rate, and a significant increase in total serum alkaline phosphatase. Finally, the detection of elevated parathyroid hormone levels indicated the diagnosis of pHPT and necessitated imaging studies of the parathyroid glands, which indicated a parathyroid adenoma. Following successful excision of the parathyroid adenoma, the patient suffered from the hungry bone syndrome. After a follow-up of 20 years, the patient had normal calcium, vitamin D, and parathyroid hormone serum levels, while a pelvic radiograph indicated no significant changes in the appearance of the brown tumors.

A practical approach to normocalcemic primary hyperparathyroidism

Normocalcemic primary hyperparathyroidism is an entity on which several issues about its clinical management remains unclear. This is reflected in the main current guidelines, where there are no evidence-based specific recommendations. Through an exhaustive review of current literature, a clinical management algorithm for these patients is proposed. We consider the diagnosis criteria, the differential diagnosis, the clinical manifestations, and the treatment indications. When indicated, we also review the preoperative locations techniques and the surgical approach. Finally, when surgical treatment is not indicated, the patient is not a candidate to surgery or refuse surgical management, we review the medical treatment options and the follow-up schemes.

Primary hyperparathyroidism: Disease of diverse genetic, symptomatic, and biochemical phenotypes

Genetic, symptomatic, and biochemical heterogeneity of patients with primary hyperparathyroidism (PHPT) has become apparent in recent years. An in-depth, evidence-based review of the phenotypes of PHPT was conducted. This review was intended to provide the resulting information to surgeons who operate on patients with hyperparathyroidism. This review revealed that the once relatively clear distinction between familial and sporadic PHPT has become more challenging by the finding of various germline mutations in patients with seemingly sporadic PHPT. On the one hand, the genetic and clinical characteristics of some syndromes in which PHPT is an important component are now better understood. On the other hand, knowledge is emerging about novel syndromes, such as the rare multiple endocrine neoplasia type IV (MEN4), in which PHPT occurs frequently. It also revealed that, currently, the classical array of symptoms of PHPT is seen rarely upon initial presentation for evaluation. More common are nonspecific, nonclassical symptoms and signs of PHPT. In areas of the world where serum calcium levels are checked routinely, most patients today are "asymptomatic" and they are diagnosed after an incidental finding of hypercalcemia; however, some of them have subclinical involvement of bones and kidneys, which is demonstrated on radiographs, ultrasound, and modern imaging techniques. Last, the review points out that there are three distinct biochemical phenotypes of PHPT. The classical phenotype in which calcium and parathyroid hormone levels are both elevated, and other disease presentations in which the serum levels of calcium or intact parathyroid hormone are normal. Today several, distinct phenotypes of the disease can be identified, and they have implications in the diagnostic evaluation and treatment of patients, as well as possible screening of relatives.

Pediatric hyperparathyroidism: review and imaging update

Hyperparathyroidism, due to increased secretion of parathyroid hormones, may be primary, secondary or tertiary. Most pediatric patients with sporadic primary hyperparathyroidism will be symptomatic, presenting with either end-organ damage or nonspecific symptoms. In younger patients with primary hyperparathyroidism, there is a higher prevalence of familial hyperparathyroidism including germline inactivating mutations of the calcium-sensing receptor genes that result in either neonatal severe hyperparathyroidism or familial hypocalciuric hypercalcemia. Parathyroid scintigraphy and ultrasound are complementary, first-line imaging modalities for localizing hyperfunctioning parathyroid glands. Second-line imaging modalities are multiphase computed tomography (CT) and magnetic resonance imaging. In pediatrics, multiphase CT protocols should be adjusted to optimize radiation dose. Although, the role of these imaging modalities is better established in preoperative localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism, the same principles apply in secondary and tertiary hyperparathyroidism. In this manuscript, we will review the embryology, anatomy, pathophysiology and preoperative localization of parathyroid glands as well as several subtypes of primary familial hyperparathyroidism. While most of the recent imaging literature centers on adults, we will focus on the issues that are pertinent and applicable to pediatrics.

Bone Quality as Measured by Trabecular Bone Score in Normocalcemic Primary Hyperparathyroidism

OBJECTIVE

The impact of normocalcemic hyperparathyroidism (NHPT) on bone quality remains largely unexplored. We aimed to investigate the usefulness of trabecular bone score (TBS) assessment in NHPT and the accuracy of TBS in predicting vertebral fractures (VFs) in NHPT.

METHODS

In this multicentric cross-sectional study, we assessed the TBS in 47 subjects with NHPT, 41 with primary hyperparathyroidism (PHPT), and 39 age- and sex-matched control subjects.

RESULTS

TBS values did not differ among the 3 groups. The prevalence of low TBS (TBS < 1.2) was 23.4% in NHPT, 26.8% in PHPT, and 15.4% in controls, without statistically significant differences between groups. However, we found a lower lumbar spine Z-score adjusted for TBS (LS Z-score∗TBS) in PHPT participants when compared with controls (-0.48 ± 1.06 vs 0.07 ± 0.93, P = .017). In NHPT group, LS Z-score∗TBS did not detect patients with overall VFs (threshold, -0.15; area under the curve, 0.45; 95% CI, 0.253-0.648; accuracy, 55.3%). Instead, it was useful for moderate-severe VFs (threshold, 0.55; area under the curve, 0.81; 95% CI, 0.62-0.996; accuracy, 83%). In PHPT subjects also, TBS did not predict VFs.

CONCLUSION

In NHPT, TBS is not reduced. When adjusted for TBS, the LS Z-score might predict moderate-to-severe VFs.

Management of parathyroid disorders: recommendations of the working group of the Bone Section of the Hellenic Endocrine Society

The Bone Section of the Hellenic Endocrine Society has issued the recommendations herein presented with the aim of providing guidance on optimal management of patients with parathyroid disorders in everyday clinical practice within the Greek health care setting. Although the methodology followed to formulate these recommendations was not strictly based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) principles, they were drawn up after an extensive review of the literature and of the currently available guidelines for the management of parathyroid disorders worldwide. Specifically for primary hyperparathyroidism (PHPT), the 2011 guidelines of the Greek National Organization of Medicines were updated accordingly. In particular, definitions, etiologies, and recommended and optional laboratory and imaging examinations are provided both for PHPT and chronic hypoparathyroidism (HypoPT). Finally, treatment algorithms are provided for the management of both PHPT and HypoPT. Specifically for HypoPT, the treatment algorithm describes the recommended steps that should be followed to achieve optimal management of chronic hypocalcemia and the complications of HypoPT through the conventional treatment available in Greece and the use of recombinant human PTH(1-84).

Clinical, Biochemical, and Radiological Profile of Normocalcemic Primary Hyperparathyroidism

CONTEXT

The clinical and radiological aspects of normocalcemic hyperparathyroidism (NHPT) are confounded by the differing methods used to rule out secondary hyperparathyroidism and by the small sample size.

OBJECTIVE

To assess the clinical, biochemical, and radiological profile of NHPT compared with primary hyperparathyroidism (PHPT) and control subjects.

DESIGN

Multicentric cross-sectional study.

SETTING

Outpatient clinic.

PATIENTS

47 NHPT, 41 PHPT, and 39 age- and sex-matched control subjects.

MAIN OUTCOME MEASURES

Calcium metabolism and bone turnover markers (BTMs). Lumbar spine, total hip, femoral neck, one-third distal radius bone mineral density (BMD). Morphometric vertebral fracture (VF) assessed by dual-energy X-ray absorptiometry.

RESULTS

NHPT patients had significantly higher parathyroid hormone, 25(OH)-vitamin D levels and lower calcium × phosphorus product than controls (P < .001). Compared with PHPT, the NHPT group had significantly higher 25(OH) vitamin D levels (P = .016). NHPT had BTM levels similar to controls and PHPT. NHPT, PHPT, and controls have similar lumbar spine and femoral neck BMD. NHPT and controls had a similar radial BMD, while patients with PHPT had a lower radial BMD than both patients with NHPT (P = .031) and controls (P < .05). Using the control group as the reference, after adjustment for interacting factors, there was no increase in risk of moderate-severe VF in NHPT (odds ratio [OR] 1.04, 95% confidence interval [CI] 0.25-4.55), while PHPT had an increased risk (OR 3.81,95% CI 1.15-15.12). Seventy-nine percent of NHPT and 59% of PHPT patients fulfilled the criteria for asymptomatic hyperparathyroidism.

CONCLUSIONS

The biochemical phenotype of NHPT is intermediate between PHPT and controls. In contrast, the bone phenotype resembles controls with normal bone turnover, no significant BMD impairment, and no increased risk of VF.

Gender Predilection in Sporadic Parathyroid Adenomas

Primary hyperparathyroidism is a common endocrinopathy that is mainly caused by benign parathyroid adenomas. The frequency, clinical presentation and complications of the disease show significant differences between genders, with the majority of cases being reported in postmenopausal women. Due to this gender predilection, several studies have investigated the role of sex hormones in the pathogenesis of the disease and their potential use as targets for optimal and gender-specific management. Epigenetic mechanisms that regulate gene transcription may also contribute to these differences between genders. In this review, we outline what is currently known regarding the role of sex hormones and the recent data on the role of non-coding RNAs in the differences between genders in primary hyperparathyroidism due to sporadic parathyroid adenomas.

Coronary artery disease is more severe in patients with primary hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism is associated with an increased cardiovascular mortality, but mechanisms underlying this association are unclear. The goal of this study was to evaluate coronary artery calcifications via the coronary calcification score in primary hyperparathyroidism patients, to compare with control subjects, and to identify risk factors for high to intermediate risk coronary calcification scores (coronary calcification score >100).

METHOD

Cross-sectional study of primary hyperparathyroidism patients without a history of coronary artery disease, diabetes, or severe, chronic kidney disease. Coronary calcification scores were compared with a cohort of population-based control subjects.

RESULTS

The mean coronary calcification score was 120 ± 344 in 130 primary hyperparathyroidism patients. The coronary calcification score was >100 in 27 patients (21%). When compared with control subjects, the percentage of positive coronary calcification scores was similar in primary hyperparathyroidism patients (53% vs 50%); however, positive coronary calcification scores were at the 67^th percentile of the control subjects cohort (P < .001). In multivariable regression, patient age (1.1; 1.1-1.2; P < .001), patients in the mild normocalcemic primary hyperparathyroidism group (5.1; 1.1-22.6; P = .037), and the need for antihypertensive medications (6.1; 1.8-20.9; P < .001) remained independent predictors for a coronary calcification score >100.

CONCLUSION

Positive coronary calcification scores were greater in primary hyperparathyroidism patients than in population-based control subjects. These study data may provide new criteria for parathyroidectomy in patients with primary hyperparathyroidism.