Hyperparathyroidism induced by hypothyroidism

Case Report: Familial Hypocalciuric Hypercalcaemia and Hashimoto's Thyroiditis

Introduction: Hypercalcaemia can be caused by many disorders. Primary hyperparathyroidism is the leading cause with parathyroidectomy being the definitive management. Familial hypocalciuric hypercalcaemia is a rarer cause in which resection of the parathyroid tissue does not result in normalized serum calcium.

Case presentation: We report the unusual case of a 53-year-old lady who presented with hypercalcaemia and elevated parathyroid hormone with a presumed diagnosis of primary hyperparathyroidism. She remained hypercalcaemic after parathyroidectomy and was later diagnosed with familial hypocalciuric hypercalcaemia. During the first operation, a lymph node was also removed, and the histopathology report suggested a metastasis of follicular variant papillary thyroid carcinoma (FVPTC). After multi-disciplinary team (MDT) discussion, the patient underwent a second exploration where total thyroidectomy and removal of the other parathyroid glands were performed. Hypercalcaemia completely resolved on surgical resection of the thyroid and parathyroid tissue, however histopathology revealed normal parathyroid glands and florid Hashimoto's thyroiditis. The initial diagnosis of FVPTC in the lymph node was revisited and the final histopathology report suggested an accessory thyroid nodule with florid Hashimoto's thyroiditis mimicking a lymph node.

Conclusion: Our case demonstrates the diagnostic dilemma in hypercalcaemia that may lead a patient to undergo unnecessary invasive procedures; the misdiagnosis of FVPTC after the first operation resulted in a second more extensive procedure. Patients with no clear surgical target and urine CCCR in the gray/non-diagnostic area should be routinely offered genetic testing despite negative family history.

Coexisting Tertiary Hyperparathyroidism and Severe Hypothyroidism in an End-Stage Renal Disease Patient on Hemodialysis

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Primary hyperparathyroidism due to an intrathyroidal parathyroid adenoma associated with chronic lymphocytic thyroiditis

This is a case of a 44-year-old woman with an anterior neck mass and hypothyroidism who presented with an incidental finding of an elevated serum calcium level and was found to have primary hyperparathyroidism and osteoporosis. During surgical exploration no parathyroid adenoma was found, although a nodule was palpated within the right thyroid lobe. Examination of the excised right thyroid lobe revealed an intrathyroidal parathyroid adenoma and chronic lymphocytic thyroiditis. After surgery, she did not develop severe hypocalcaemia and this was attributed to preoperative treatment with pamidronate. In the months following surgery, parathyroid hormone remained undetectable.

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.