Hypercalcaemic Crisis Due to Primary Hyperparathyroidism: Report of Two Cases

Severe hypercalcemia secondary to parathyroid adenoma: Series of four consecutive cases at a tertiary care hospital in Qatar

INTRODUCTION

In most cases of parathyroid adenoma (PA), it is not palpable and physical examination shows no remarkable findings. Hence diagnosis requires an index of suspicion. The current paper describes four cases of severe hypercalcemia secondary to PA.

PRESENTATION OF CASES

Case 1 - 29 years old Sudanese female with history of nausea/vomiting, fatigue, loss of appetite and bone aches. She had large palpable left lower neck swelling, and high calcium and PTH. Ultrasound (US) neck and SPECT/CT scan after sestamibi injection showed left inferior PA. Case 2-73 years old Sudanese male referred with history of abdominal pain and flatulence. He had severely high calcium, elevated parathormone (PTH), and high 24-hour urine calcium. US and SPECT/CT showed a left inferior PA. Case 3-54 years old Bangladeshi male, referred with history of renal colic/urolithiasis. Laboratory results showed severely high calcium and PTH levels. US and SPECT/CT scan showed right inferior PA. Case 4-35 years old Tunisian female, 12 weeks pregnant, referred with recurrent nausea and vomiting of increasing frequency from the second week of pregnancy. Laboratory tests revealed severe hypercalcemia and high PTH. US showed two parathyroid lesions.

DISCUSSION

The patients were admitted as emergency cases and investigations diagnosed severe hypercalcemia secondary to PA. All patients underwent neck exploration and PA excision. Histology confirmed PA. The four cases were swiftly assessed and treated before progressing into the more serious hypercalcemic crisis which can lead to grave consequences, particularly in the case of the pregnant female. All patients recovered with no complications and were clinically well with normal calcium level on follow up.

CONCLUSION

Severe hypercalcemia must be swiftly and thoroughly assessed to prevent the more serious hypercalcemic crisis. Clinicians need to be suspicious of parathyroid adenoma as a probable cause. Severe hypercalcemia is often accompanied with vomiting, and in pregnant females, this could be mistaken for hyperemesis gravidarum. Excision of the parathyroid adenoma treats the condition and follow up of serum calcium and PTH confirms the favorable outcome of surgery.

Parathyroid Crisis: A Case of Elective Parathyroidectomy

A parathyroid crisis is characterized by a severe elevation in calcium, usually above 14-15 mg/dl alongside acute signs and symptoms of hypercalcemia. It is a rare but potentially life-threatening complication of primary hyperparathyroidism (PHPT). Among all primary hyperparathyroidism cases, parathyroid carcinoma accounts for only less than 1%. Although the definitive management is surgical parathyroidectomy, the exact timing of surgery is not well-established. We describe a case of a patient with abrupt onset of severe hypercalcemia who was managed medically and discharged for elective parathyroidectomy. This was because her workup was suspicious for parathyroid carcinoma, and there was a need to pursue a positron emission tomography (PET)-computed tomography (CT) scan to evaluate for other malignancies before proceeding with parathyroidectomy. The patient experienced the resolution of her symptoms of acute encephalopathy and improvement in her calcium levels from 22.3 mg/dl (8.8-10.2 mg/dl) on admission to 9.1 mg/dl on day 13 of hospitalization and discharge. In this report, we review the literature on the timing of parathyroidectomy in patients with a parathyroid crisis and how this has evolved over time with the use of new hypocalcemic agents. We discuss that parathyroidectomy performed emergently within 72 hours vs after 72 hours has not shown any significant impact on long-term survival in patients with parathyroid crisis. Moreover, medical management is crucial while waiting for surgery.

Common Key Genes in Differentiating Parathyroid Adenoma From Thyroid Adenoma

Recent studies have demonstrated the close relationship between parathyroid adenoma (PA) and thyroid follicular adenoma (FTA). However, the underlying pathogenesis remains unknown. This study focused on exploring common pathogenic genes, as well as the pathogenesis of these two diseases, through bioinformatics methods. This work obtained PA and FTA datasets from the Integrated Gene Expression Database to identify the common differentially expressed genes (DEGs) of two diseases. The functions of the genes were investigated by GO and KEGG enrichment. The program CytoHubba was used to select the hub genes, while receiver operating characteristic curves were plotted to evaluate the predictive significance of the hub genes. The DGIbd database was used to identify gene-targeted drugs. This work detected a total of 77 DEGs. Enrichment analysis demonstrated that DEGs had activities of 3',5'-cyclic AMP, and nucleotide phosphodiesterases and were associated with cell proliferation. NOS1, VWF, TGFBR2, CAV1, and MAPK1 were identified as hub genes after verification. The area under the curve of PA and FTA was>0.7, and the hub genes participated in the Relaxin Signaling Pathway, focal adhesion, and other pathways. The construction of the mRNA-miRNA interaction network yielded 11 important miRNAs, while gene-targeting drug prediction identified four targeted drugs with possible effects. This bioinformatics study demonstrated that cell proliferation and tumor suppression and the hub genes co-occurring in PA and FTA, have important effects on the occurrence and progression of two diseases, which make them potential diagnostic biomarkers and therapeutic targets.

Overview of the 2022 WHO Classification of Parathyroid Tumors

The 2022 WHO classification reflects increases in the knowledge of the underlying pathogenesis of parathyroid disease. In addition to the classic characteristic features of parathyroid neoplasms, subtleties in histologic features which may indicate an underlying genetic abnormality reflect increased understanding of the clinical manifestations, histologic, and genetic correlation in parathyroid disease. The importance of underlying genetic aberrancies is emphasized due to their significance to the care of the patient. Traditionally, the term "parathyroid hyperplasia" has been applied to multiglandular parathyroid disease; however, the concept of hyperplasia is generally no longer supported in the context of primary hyperparathyroidism since affected glands are usually composed of multiple "clonal" neoplastic proliferations. In light of these findings and management implications for patient care, the 2022 WHO classification endorses primary hyperparathyroidism-related multiglandular parathyroid disease (multiglandular multiple parathyroid adenomas) as a germline susceptibility-driven multiglandular parathyroid neoplasia. From such a perspective, pathologists can provide additional value to genetic triaging by recognizing morphological and immunohistochemical harbingers of MEN1, CDKN1B, MAX, and CDC73-related manifestations. In the current WHO classification, the term "parathyroid hyperplasia" is now used primarily in the setting of secondary hyperplasia which is most often caused by chronic renal failure. In addition to expansion in the histological features, including those that may be suggestive of an underlying genetic abnormality, there are additional nomenclature changes in the 2022 WHO classification reflecting increased understanding of the underlying pathogenesis of parathyroid disease. The new classification no longer endorses the use of "atypical parathyroid adenoma". This entity is now being replaced with the term of "atypical parathyroid tumor" to reflect a parathyroid neoplasm of uncertain malignant potential. The differential diagnoses of atypical parathyroid tumor are discussed along with the details of worrisome clinical and laboratory findings, and also features that define atypical histological and immunohistochemical findings to qualify for this diagnosis. The histological definition of parathyroid carcinoma still requires one of the following findings: (i) angioinvasion (vascular invasion) characterized by tumor invading through a vessel wall and associated thrombus, or intravascular tumor cells admixed with thrombus, (ii) lymphatic invasion, (iii) perineural (intraneural) invasion, (iv) local malignant invasion into adjacent anatomic structures, or (v) histologically/cytologically documented metastatic disease. In parathyroid carcinomas, the documentation of mitotic activity (e.g., mitoses per 10mm²) and Ki67 labeling index is recommended. Furthermore, the importance of complete submission of parathyroidectomy specimens for microscopic examination, and the crucial role of multiple levels along with ancillary biomarkers have expanded the diagnostic workup of atypical parathyroid tumors and parathyroid carcinoma to ensure accurate characterization of parathyroid neoplasms. The concept of parafibromin deficiency has been expanded upon and term "parafibromin deficient parathyroid neoplasm" is applied to a parathyroid neoplasm showing complete absence of nuclear parafibromin immunoreactivity. Nucleolar loss is considered as abnormal finding that requires further molecular testing to confirm its biological significance. The 2022 WHO classification emphasizes the role of molecular immunohistochemistry in parathyroid disease. By adopting a question-answer framework, this review highlights advances in knowledge of histological features, ancillary studies, and associated genetic findings that increase the understanding of the underlying pathogenesis of parathyroid disease that are now reflected in the updated classification and new entities in the 2022 WHO classification.