Oxyphil parathyroid adenoma associated with primary hyperparathyroidism and marked post-operative hungry bone syndrome

Forestalling Hungry Bone Syndrome after Parathyroidectomy in Patients with Primary and Renal Hyperparathyroidism

Hungry bone syndrome (HBS), severe hypocalcemia following parathyroidectomy (PTX) due to rapid drop of PTH (parathormone) after a previous long term elevated concentration in primary (PHPT) or renal hyperparathyroidism (RHPT), impairs the outcome of underlying parathyroid disease.

OBJECTIVE

overview HBS following PTx according to a dual perspective: pre- and post-operative outcome in PHPT and RHPT. This is a case- and study-based narrative review.

INCLUSION CRITERIA

key research words "hungry bone syndrome" and "parathyroidectomy"; PubMed access; in extenso articles; publication timeline from Inception to April 2023.

EXCLUSION CRITERIA

non-PTx-related HBS; hypoparathyroidism following PTx. We identified 120 original studies covering different levels of statistical evidence. We are not aware of a larger analysis on published cases concerning HBS (N = 14,349). PHPT: 14 studies (N = 1545 patients, maximum 425 participants per study), and 36 case reports (N = 37), a total of 1582 adults, aged between 20 and 72. Pediatric PHPT: 3 studies (N = 232, maximum of 182 participants per study), and 15 case reports (N = 19), a total of 251 patients, aged between 6 and 18. RHPT: 27 studies (N = 12,468 individuals, the largest cohort of 7171) and 25 case reports/series (N = 48), a total of 12,516 persons, aged between 23 and 74. HBS involves an early post-operatory (emergency) phase (EP) followed by a recovery phase (RP). EP is due to severe hypocalcemia with various clinical elements (<8.4 mg/dL) with non-low PTH (to be differentiated from hypoparathyroidism), starting with day 3 (1 to 7) with a 3-day duration (up to 30) requiring prompt intravenous calcium (Ca) intervention and vitamin D (VD) (mostly calcitriol) replacement. Hypophosphatemia and hypomagnesiemia may be found. RP: mildly/asymptomatic hypocalcemia controlled under oral Ca+VD for maximum 12 months (protracted HBS is up to 42 months). RHPT associates a higher risk of developing HBS as compared to PHPT. HBS prevalence varied from 15% to 25% up to 75-92% in RHPT, while in PHPT, mostly one out of five adults, respectively, one out of three children and teenagers might be affected (if any, depending on study). In PHPT, there were four clusters of HBS indicators. The first (mostly important) is represented by pre-operatory biochemistry and hormonal panel, especially, increased PTH and alkaline phosphatase (additional indicators were elevated blood urea nitrogen, and a high serum calcium). The second category is the clinical presentation: an older age for adults (yet, not all authors agree); particular skeleton involvement (level of case reports) such as brown tumors and osteitis fibrosa cystica; insufficient evidence for the patients with osteoporosis or those admitted for a parathyroid crisis. The third category involves parathyroid tumor features (increased weight and diameter; giant, atypical, carcinomas, some ectopic adenomas). The fourth category relates to the intra-operatory and early post-surgery management, meaning an associated thyroid surgery and, maybe, a prolonged PTx time (but this is still an open issue) increases the risk, as opposite to prompt recognition of HBS based on calcium (and PTH) assays and rapid intervention (specific interventional protocols are rather used in RHPT than in PHPT). Two important aspects are not clarified yet: the use of pre-operatory bisphosphonates and the role of 25-hydroxyitamin D assay as pointer of HBS. In RHPT, we mentioned three types of evidence. Firstly, risk factors for HBS with a solid level of statistical evidence: younger age at PTx, pre-operatory elevated bone alkaline phosphatase, and PTH, respectively, normal/low serum calcium. The second group includes active interventional (hospital-based) protocols that either reduce the rate or improve the severity of HBS, in addition to an adequate use of dialysis following PTx. The third category involves data with inconsistent evidence that might be the objective of future studies to a better understanding; for instance, longer pre-surgery dialysis duration, obesity, an elevated pre-operatory calcitonin, prior use of cinalcet, the co-presence of brown tumors, and osteitis fibrosa cystica as seen in PHPT. HBS remains a rare complication following PTx, yet extremely severe and with a certain level of predictability; thus, the importance of being adequately identified and managed. The pre-operatory spectrum of assessments is based on biochemistry and hormonal panel in addition to a specific (mostly severe) clinical presentation while the parathyroid tumor itself might provide useful insights as potential risk factors. Particularly in RHPT, prompt interventional protocols of electrolytes surveillance and replacement, despite not being yet a matter of a unified, HBS-specific guideline, prevent symptomatic hypocalcemia, reduce the hospitalization stay, and the re-admission rates.

Risk factors and evolution of calcium and parathyroid hormone levels in hungry bone syndrome after parthyroidectomy for primary hyperparathyroidism

INTRODUCTION

Hungry bone syndrome (HBS) is a complication occurring after parathyroid surgery that can cause severe and prolonged hypocalcemia. The study objective was to know the risk factors for HBS after surgery for primary hyperparathyroidism and its relationship with serum calcium and parathyroid hormone levels.

MATERIAL AND METHODS

A case-control, observational, analytical study was conducted in patients who had undergone surgery for primary hyperparathyroidism in the past 10 years (2007-2016). Changes over time in serum calcium and PTH levels and the general characteristics of patients were analyzed.

RESULTS

The incidence rate of HBS in our series was 12.2%. HBS was found to be significantly associated to thyroid surgery during the surgical procedure itself (adjusted odds ratio [aOR]=17.241), to age older than 68 years (aOR=6.666), and to lesions greater than 1.7cm (aOR=7.165). A statistically significant relationship was seen between presence of HBS and corrected serum calcium levels higher than the mean the day after surgery and one week and 3 months later, and also with PTH levels higher than the mean before, during, and one day after surgery.

CONCLUSION

In our series, independent risk factors for development of HBS included patient age, lesion size, and whether or not the procedure was accompanied by thyroid surgery, which requires closer monitoring of mineral metabolism during the perioperative period.

Atypical Parathyroid Adenoma Complicated with Protracted Hungry Bone Syndrome after Surgery: A Case Report and Literature Review

Hungry Bone Syndrome refers to the severe and prolonged hypocalcemia and hypophosphatemia, following parathyroidectomy in patients with hyperparathyroidism. We present the case of an eighteen-year-old woman with a four-year history of hyporexia, polydipsia, weight loss, growth retardation, and poor academic performance. The diagnostic work-up demonstrated primary hyperparathyroidism with hypercalcemia of 13.36 mg/dL, a PTH level of 2551 pg/mL, bone brown tumors, and microcalcifications within pancreas and kidneys. Neck ultrasonography revealed a parathyroid adenoma of 33 × 14 × 14 mm, also identified on (99)Tc-sestamibi scan. Bone densitometry showed decreased Z-Score values (total lumbar Z-Score of -4.2). A right hemithyroidectomy and right lower parathyroidectomy were performed. Pathological examination showed an atypical parathyroid adenoma, of 3.8 g of weight and 2.8 cm in diameter. After surgery she developed hypocalcemia with tetany and QTc interval prolongation. The patient required 3 months of oral and intravenous calcium supplementation due to Hungry Bone Syndrome (HBS). After 42 months, she is still under oral calcium. Usually HBS lasts less than 12 months. Therefore we propose the term "Protracted HBS" in patients with particularly long recovery of 1 year. We present a literature review of the diagnosis, pathophysiology, and treatment of HBS.

Hungry bone syndrome: still a challenge in the post-operative management of primary hyperparathyroidism: a systematic review of the literature

Hungry bone syndrome (HBS) refers to the rapid, profound, and prolonged hypocalcaemia associated with hypophosphataemia and hypomagnesaemia, and is exacerbated by suppressed parathyroid hormone (PTH) levels, which follows parathyroidectomy in patients with severe primary hyperparathyroidism (PHPT) and preoperative high bone turnover. It is a relatively uncommon, but serious adverse effect of parathyroidectomy. We conducted a literature search of all available studies reporting a 'hungry bone syndrome' in patients who had a parathyroidectomy for PHPT, to identify patients at risk and address the pitfalls in their management. The severe hypocalcaemia is believed to be due to increased influx of calcium into bone, due to the sudden removal of the effect of high circulating levels of PTH on osteoclastic resorption, leading to a decrease in the activation frequency of new remodelling sites and to a decrease in remodelling space, although there is no good documentation for this. Various risk factors have been suggested for the development of HBS, including older age, weight/volume of the resected parathyroid glands, radiological evidence of bone disease and vitamin D deficiency. The syndrome is reported in 25-90% of patients with radiological evidence of hyperparathyroid bone disease vs only 0-6% of patients without skeletal involvement. There is insufficient data-based evidence on the best means to treat, minimise or prevent this severe complication of parathyroidectomy. Treatment is aimed at replenishing the severe calcium deficit by using high doses of calcium supplemented by high doses of active metabolites of vitamin D. Adequate correction of magnesium deficiency and normalisation of bone turnover are required for resolution of the hypocalcaemia which may last for a number of months after successful surgery. Preoperative treatment with bisphosphonates has been suggested to reduce post-operative hypocalcaemia, but there are to date no prospective studies addressing this issue.

Primary hyperparathyroidism with classic and severe skeletal involvement

A 63-year-old woman has had multiple repeated fractures. A diagnosis of primary hyperparathyroidism (PHPT) was made after she was found to be hypercalcaemic with an elevated level of intact parathyroid hormone (iPTH). Radiographs revealed classic and severe bone findings in PHPT, features which were common in the past but are thought to be rare at this modern age. She also had nephrolithiasis and osteoporosis. An enlarged parathyroid gland was seen on ultrasound and CT scan, and hyperfunction was demonstrated by scintigraphy. Parathyroidectomy was performed. Histopathologic analysis revealed a parathyroid adenoma. She developed the hungry-bone syndrome 7 days postoperatively, which resolved with with administration of calcium and calcitriol.

[Functioning oxyphil cell adenoma of parathyroid diagnosed with ureteral stone]

A case of oxyphil cell adenoma of parathyroid is presented. A 82-year-old woman complained of back pain. Left hydronephrosis, elevated serum calcium-parathyroid hormone and a nodule in the right neck suggested functioning parathyroid adenoma. Resected adenoma (15 mm x 10 mm x 5 mm) was exclusively composed of oxyphil cell. Production of parathyroid hormone by oxyphil cells was confirmed by immunohistochemistry. This case was found to be the smallest parathyroid oxyphil cell adenoma hitherto reported that caused urolithiasis.

Oxyphil parathyroid adenoma: a malignant presentation of a benign disease

Functioning parathyroid adenomas of the oxyphil cell type are rare, and the clinical characteristics of patients with these tumors have not been well defined. We describe two cases of severe primary hyperparathyroidism (PHPT) caused by benign oxyphil parathyroid adenomas. The patients' clinical presentations mimicked parathyroid carcinoma. Both had very large tumors associated with marked elevations in PTH and serum calcium levels. Skeletal manifestations were also atypical for benign PHPT, with severe osteoporosis in one patient and osteitis fibrosa cystica in the other. These cases also highlight the remarkable capacity of the skeleton to recover after successful parathyroidectomy, previously reported in other forms of severe PHPT. Bone mineral density improved dramatically 1 yr after parathyroidectomy, with increases of 51% at the lumbar spine, 36% at the total hip, and 11% at the distal one third radius. Most of the increases occurred in the first postoperative months. Consistent with this early and accelerated skeletal response, markers of bone turnover were increased 2 months after surgery and normalized by 8 months postoperatively. In patients with PHPT who present with severe or atypical clinical features, oxyphil adenoma should be considered.

Metachronous Double Parathyroid Adenomas Involving Two Different Cell Types: Chief Cell and Oxyphil Cell

OBJECTIVE

To describe a patient with the rare occurrence of metachronous double parathyroid adenomas involving two different cell types.

METHODS

We present a case report and a summary of the related literature.

RESULTS

Double parathyroid adenomas are rare, occurring in 1.7 to 9% of patients with primary hyperparathyroidism. Most double parathyroid adenomas are synchronous lesions; few metachronous double parathyroid adenomas have previously been reported. Most parathyroid adenomas are of the chief cell variety, with oxyphil cell adenomas occurring in less than 1% of cases. In a 73-year-old man with no prior history or known family history of endocrine disease, primary hyperparathyroidism developed, and cervical ultrasonography demonstrated a mass in the right side of the neck. Subsequent parathyroidectomy revealed a right superior chief cell adenoma. Postoperatively, the patient's parathyroid hormone and serum calcium levels returned to normal and remained so for at least 9 years. Twelve years after the first operation, recurrent hyperparathyroidism prompted repeated surgical exploration of the neck, which disclosed a large left superior parathyroid mass. Surgical excision and histologic examination revealed the lesion to be an oxyphil cell adenoma.

CONCLUSION

To our knowledge, this is the first reported case of metachronous double parathyroid adenomas involving two different cell types: chief cell and oxyphil cell.