A clinical evaluation of radiation-induced hyperparathyroidism based on 148 surgically treated patients

Primary hyperparathyroidism after radioactive iodine therapy: Is it a distinct clinical entity?

BACKGROUND

Radioactive iodine (RAI) treatment is considered a rare cause of primary hyperparathyroidism (pHPT).

METHOD

A multi-institutional retrospective review of patients with pHPT who underwent parathyroidectomy from 1990 to 2020 was completed to evaluate the prevalence and latency time for development of RAI-associated pHPT and determine clinical differences in pHPT patients with or without prior RAI treatment.

RESULTS

1929 patients with sporadic pHPT underwent parathyroidectomy; 48 (2.5%) had prior RAI treatment and 1881 (97.5%) did not. RAI treatment was for thyrotoxicosis in 43 (90%) patients. Average latency was 24 years (3-59 years) and inversely correlated with age. Patients with prior RAI treatment had lower preoperative calcium and PTH levels (p < 0.0001). No significant differences were observed in age, symptoms, pathology, ectopic glands and cure rate.

CONCLUSION

RAI is a potential causative factor for pHPT, accounting for 2.5% of sporadic pHPT. RAI-associated pHPT may be a less severe form of sporadic pHPT and latency inversely correlates with age.

Bilateral neck exploration in primary hyperparathyroidism--when is it selected and how is it performed?

BACKGROUND

Although most patients with primary hyperparathyroidism (PHPT) are ideal candidates for minimally invasive parathyroidectomy, some will have more than one enlarged gland and require bilateral neck exploration to achieve biochemical cure. We evaluated the clinical evidence for when to choose bilateral neck exploration for patients with PHPT.

METHODS

We searched PubMed for English-language studies published from 1996 to 2008. The level of clinical evidence was determined according to the criteria proposed by Sackett (Chest 95[2 Suppl]:2S, 1989), and the grade of recommendation was established according to the criteria proposed by Heinrich et al. (Ann Surg 243:154, 2006).

RESULTS

Level III-IV evidence shows that patients with multiple endocrine neoplasia (MEN) 1 and PHPT should have a bilateral neck exploration (grade C recommendation). Only level IV evidence indicates that patients with familial PHPT should do so (no recommendation). Although most patients with MEN 2A have single-gland disease, bilateral neck exploration is still indicated, because they will have either a therapeutic or prophylactic total thyroidectomy for medullary thyroid cancer. A history of head and neck irradiation is associated with PHPT, but the risk of multi-gland parathyroid disease is apparently no higher than in sporadic cases (level IV evidence, no recommendation). Previous or current lithium therapy confers a higher risk of multi-gland disease (25%-45%; level IV-V evidence), which may require bilateral neck exploration. Preoperative localizing studies reliably identify most patients with single-gland but not multi-gland disease (level II-IV evidence). Negative localizing studies confer an approximately 50% risk of multi-gland disease and indicate that bilateral neck exploration is necessary. If two localizing studies are concordant, few patients will require bilateral neck exploration (level IV, no recommendation).

CONCLUSIONS

No level I or II evidence reliably identifies preoperative clinical risk factors for determining which patients should have routine bilateral neck exploration for multi-gland disease or for intraoperative decision making to convert to bilateral neck exploration. Imaging studies are positive in most patients (level II). No randomized studies exist to determine when a bilateral neck exploration is indicated based on clinical risk factors or imaging studies that may suggest multi-gland disease.

Prior head and neck radiation exposure is not a contraindication to minimally invasive parathyroidectomy

BACKGROUND

Most patients with primary hyperparathyroidism can have a minimally invasive parathyroidectomy based on localization studies showing single-gland disease. In patients with a history of head and neck irradiation, due to the increased risk of multigland disease and risk of concurrent thyroid cancer, minimally invasive parathyroidectomy is considered by some to be a contraindication. We postulated that previous history of head and neck irradiation should not be a contraindication for minimally invasive parathyroidectomy and tested this hypothesis in a prospective cohort of patients undergoing parathyroidectomy for primary hyperparathyroidism.

STUDY DESIGN

We performed a retrospective analysis of a prospective database of 491 consecutive parathyroidectomies performed between May 2005 and May 2007 at a tertiary referral medical center.

RESULTS

Fifty-two (12.6%) patients had a history of head and neck irradiation and 360 (87.4%) had no exposure to radiation. The 2 groups had no significant difference in terms of gender or ethnicity. The radiation group was older, with an average age of 65.1 years versus 58.1 years (p < 0.0009). There was no significant difference in concurrent benign thyroid neoplasm, thyroid cancer, and type of parathyroid disease (single vs multigland) in the 2 groups. There was no significant difference in the operative approach used between the 2 groups (focused vs unilateral or bilateral).

CONCLUSIONS

Head and neck irradiation should not be a contraindication for minimally invasive parathyroidectomy in patients with primary hyperparathyroidism in the setting of preoperative localization studies showing single-gland disease and no concurrent thyroid neoplasm. Furthermore, history of head and neck irradiation is associated with a later age of presentation for parathyroidectomy.

Endocrine sequelae of cancer and cancer treatments

INTRODUCTION

Exposure to cancer and its treatments, including chemotherapy and radiotherapy, may result in late adverse effects including endocrine dysfunction. Endocrine disorders are the most commonly reported long-term complications of cancer treatment, especially by adult survivors of childhood cancers. This review will explore the endocrinologic adverse effects from non-endocrine cancer therapies.

METHODS

Searches including various Internet-based medical search engines such as PubMed, Medline Plus, and Google Scholar were conducted for published articles.

RESULTS

One hundred sixty-nine journal articles met the inclusion criteria. They included case reports, systematic analyses, and cohort reports. Endocrine disorders including hypothalamus dysfunction, hypopituitarism, syndrome of inappropriate anti-diuretic hormone secretion, diabetes insipidus, growth hormone disorders, hyperprolactinemia, gonadotropin deficiency, serum thyroid hormone-binding protein abnormalities, hypothyroidism, hyperthyroidism, hypomagnesium, hypocalcemia, hyperparathyroidism, hyperparathyroidism, adrenal dysfunction, gonadal dysfunction, hypertriglyceridemia, hypercholesterolemia, diabetes mellitus, and glycosuria were identified and their association with cancer therapies were outlined.

DISCUSSION/CONCLUSIONS

The journal articles have highlighted the association of cancer therapies, including chemotherapy and radiotherapy, with endocrine dysfunction. Some of the dysfunctions were more often experienced than others. Especially in patients treated with radiotherapy, some endocrinologic disorders were progressive in nature.

IMPLICATIONS FOR CANCER SURVIVORS

Recognition and awareness of endocrine sequelae of cancer treatments may permit for early detection and appropriate follow-up care for cancer survivors, thus improving their overall health and quality of life.

Hyperparathyroidism after radioactive iodine therapy

BACKGROUND

Radioactive iodine (RAI) treatment has been suggested to cause primary hyperparathyroidism (HPT). We describe a series of patients with HPT and a history of RAI exposure.

METHODS

Patient demographic and clinical information was evaluated, including the latency time to the development of HPT after RAI exposure.

RESULTS

We treated 11 patients with HPT and a history of RAI exposure. RAI treatment was administered for benign thyroid disease in 9 (82%) cases. Thirty-six cases of HPT after RAI exposure in the English literature were compiled for further analysis. In this collective experience, the average latency time to the development of HPT after RAI treatment was 13.5 +/- 9.1 years and was found to be inversely correlated with age at RAI exposure.

CONCLUSIONS

Patients who undergo RAI treatment are at risk of developing HPT, and this risk appears to increase in elderly patients. Serum calcium surveillance is recommended for patients who have undergone RAI treatment.

The coming of age of radiation-induced hyperparathyroidism: evolving patterns of thyroid and parathyroid disease after head and neck irradiation

BACKGROUND

This study investigates the association of thyroid and parathyroid disease in radiation-exposed patients and tests the hypothesis that hyperparathyroidism (HPT) occurs after a longer latency period.

METHODS

Routine questioning identified 40 patients in the endocrine surgery clinic with a history of radiation exposure. Patients with thyroid disease were screened for HPT and vice versa.

RESULTS

The known diagnosis at initial referral was thyroid disease alone in 26 of 40 patients, HPT alone in 9 of 40 patients, and both in 5 of 40 patients. After screening was completed, a total of 18 of 40 patients were found to have both thyroid disease and HPT. HPT manifested an average of 17 years later than thyroid disease (52.6 +/- 10.0 years vs 35.5 +/- 13.8 years after radiation therapy [ P < .05]). One third of the patients with HPT had normal serum calcium levels despite elevated parathyroid hormone levels and abnormal parathyroid glands.

CONCLUSION

As the widespread use of x-ray therapy for benign childhood conditions becomes more remote, practitioners should expect a decreasing number of patients with radiation-associated thyroid disease, with an increase in HPT. Patients with radiation exposure and thyroid disease should be evaluated carefully and followed for HPT. Those patients who undergo surgical procedures should have close inspection of the parathyroid glands, with biopsy and excision when appropriate.

Effects of prior neck radiation therapy on clinical features of primary hyperparathyroidism and associated thyroid tumors

OBJECTIVE

To compare the clinical and biochemical features, bone densitometry data, and results of diagnostic imaging to localize parathyroid tumors in patients with radiation-associated hyperparathyroidism (R-HPT) and patients with HPT who had no history of radiation exposure (NR-HPT).

METHODS

We performed a retrospective analysis of 34 patients with HPT who underwent evaluation and subsequent neck exploration between 1990 and 1995. We recorded and compared the symptoms, biochemical findings, bone densitometry data, results of diagnostic imaging, and pathologic findings in R-HPT and NR-HPT groups.

RESULTS

The R-HPT group (8 men and 4 women)generally was older than the NR-HPT group (14 men and 8 women), but the age difference was not statistically significant. Patients in the R-HPT group had received radiotherapy (6.9 to 21.7 Gy) between 2 and 9 years of age for various diagnoses. Eight patients (67%) in the R-HPT group and 13 (59%) in the NR-HPT group had no symptoms of HPT. The rest of the patients in both groups had nonspecific symptoms, such as fatigue and dyspepsia. Four patients (18%) in the NR-HPT group had nephrolithiasis, and 3 (14%) had skeletal manifestations at initial assessment. Serum calcium, phosphorus, and parathyroid hormone levels and 24-hour urine calcium excretion were similar in both groups. Mean lumbar spine bone mineral density was lower in women in the R-HPT group than in those in the NR-HPT group, but the prevalence of osteoporosis did not differ significantly in the two study groups. Sestamibi scintigraphy accurately localized adenomas in both groups equally well (sensitivity >90%). In the R-HPT group, 11 patients had a single parathyroid adenoma and 1 had hyperplasia of all four parathyroid glands. In the NR-HPT group, 21 patients had a single parathyroid adenoma and 1 had parathyroid hyperplasia. In nine patients in the R-HPT group, ultrasonography showed thyroid nodules >1 cm. Pathologic examination of surgical specimens in the R-HPT group confirmed thyroid carcinoma in 11 patients ( 10 papillary and 1 follicular can-cer); no patient in the NR-HPT group had thyroid cancer. Six weeks after thyroidectomy, patients with thyroid can-cer received 1311 (mean dose, 145 mCi), five of whom needed additional 1311 treatments.

CONCLUSION

Patients with a history of childhood neck irradiation who have HPT have a high likelihood of coexisting thyroid cancer. This observation may justify surgical exploration rather than vigilant follow-up in asymptomatic patients with primary HPT and coexisting thyroid nodules who have a history of radiation exposure.

Thyroid surgery and anaesthesia following head and neck irradiation for childhood malignancy

BACKGROUND

Increasing numbers of adolescents and young adults are undergoing thyroid surgery because of the risk of malignancy following previous irradiation for childhood malignancy. Irradiation to the head and/or neck regions may induce changes in the soft tissues and larynx that are far from normal with respect to both size and mobility. The aim of the present study was to evaluate the possible impact of such changes on both surgical and anaesthetic technique during thyroidectomy.

METHODS

This was a retrospective ease study. Thirty consecutive patients undergoing total thyroidectomy following previous irradiation for childhood malignancy formed the study group.

RESULTS

There were no permanent surgical or anaesthetic complications in the group. In particular there were no cases of either permanent recurrent laryngeal nerve palsy or permanent hypoparathyroidism. Twenty-eight patients had an uneventful intubation and two were unable to be intubated directly, one requiring fibre-optic bronchoscopic intubation and the other having surgery performed with a laryngeal mask following failed bronchoscopy. Both of these patients had received high-dose direct irradiation to the larynx for solid tumours.

CONCLUSIONS

Despite potential difficulties associated with the heavily irradiated larynx, thyroid surgery and anaesthesia can be performed safely with minimal complications in experienced hands.

Parathyroid adenoma after radiation in an 8-year-old boy

We describe an 8-year-old boy who had asymptomatic hypercalcemia 4 years after radiotherapy involving the left orbit and lungs. A right parathyroid adenoma was diagnosed, and normocalcemia was achieved after its removal. Routine monitoring of serum calcium and phosphate levels is recommended for children after head and neck irradiation.

Hyperparathyroidism associated with a chronic hypothyroid state

Reports of the coexistence of hyperparathyroidism and thyroid disease have raised the issue of a possible etiologic relationship. The present study tests the hypothesis that chronic elevation of thyroid-stimulating hormone (TSH) is related to the development of hyperparathyroidism. Four groups of 60 female rats were treated as follows: group 1, control; group 2, propylthiouracil (PTU) 0.0025%; group 3, PTU 0.0025% plus thyroxine, 5 microg two times per week; and group 4, only thyroxine. The animals' serum calcium, phosphorus, TSH, thyroxine, and parathyroid hormone (PTH) levels were evaluated at 0, 6, 12, and 18 months. Significant elevation of TSH was sustained throughout the 18 months in groups 2 and 3. The PTH levels were also significantly elevated in both group 2 and group 3 animals (P = 0.02). The histopathologic features of the parathyroids were evaluated at 18 months. In the group 2 (PTU only) animals, which had profound hypothyroid, 44% developed parathyroid adenomas. In the group 3 (PTU plus thyroxine) animals, who had mildly elevated TSH levels, 53% developed parathyroid adenomas. These findings are consistent with the hypothesis that prolonged TSH stimulation may lead to hyperparathyroidism in the rat model.

Simultaneous presentation of parathyroid, thyroid and parotid tumours 44 years after neck irradiation

A case of three tumours presenting 44 years following external irradiation to the neck is reported. Whilst thyroid, parotid and parathyroid tumours are all described in this situation, the simultaneous presentation of all three has not been documented previously.

Differentiated thyroid cancer in children

Differentiated thyroid cancer in children remains a controversial disease entity. Its incidence has markedly declined over the last decade since the use of radiotherapy in the treatment of benign conditions of the head, neck, and thorax was abandoned. Other etiologic factors have become relatively more important. The clinical presentation of childhood thyroid cancer is similar to that found in adults, except for a higher frequency of local and distant metastases at the time of initial diagnosis. The specificity and sensitivity of diagnostic tests are limited; however, like in adults, fine-needle aspiration compares favorably with other available diagnostic methods. The therapeutic approach to a child with thyroid cancer represents the most controversial issue associated with the disease. This review provides a discussion of the rationale for the different therapeutic options and emphasizes the excellent prognosis and survival rates, especially when patients are subjected to aggressive treatment with total thyroidectomy followed by the administration of radioactive iodine.

Hyperparathyroidism subsequent to neck irradiation. Risk factors

A follow-up examination of 444 persons treated with x-rays for tuberculous cervical adenitis was performed to determine if the risk for hyperparathyroidism (HPT) following radiation exposure can be related to the age at treatment, the dose of x-rays, or the sex of the patient. The overall incidence of HPT was 14%. There was no definite age-dependent difference in susceptibility to the induction of HPT. The doses of radiation among the 63 subjects who developed HPT ranged from 0.6 to 45.7 Gy (60-4570 rad). There was a statistically significant positive correlation between the dose of radiation and the probability of developing HPT. After doses of 14 Gy (1400 rad) or more 29% of the subjects had developed HPT. After neck irradiation women had twice the relative risk of men of developing HPT. This sex ratio was lower than in the series of nonirradiated HPT patients treated at the same institution during the time of the follow-up study.