Coexisting hyperparathyroidism with thyrotoxicosis

Abstract

The coexistence of hyperparathyroidism complicating thyrotoxicosis is quite rare. We report the case of one patient who presented with thyrotoxicosis, (total thyroxine of 15.1 micrograms/dl (5-13), free thyroxine index of 18 (4-15) and triiodothyronine by RIA of 305 ng/dl (70-230) and asymptomatic hypercalcemia of 15 mg/dl (8.5-10.6), who was also initially noted to have an elevated (C-terminal) serum immunoreactive parathyroid hormone (iPTH) level of 8,800 pg/ml (50-340). With propylthiouracil and propranolol, however, this patient became normocalcemic with a decrease in iPTH values to 714 pg/ml. As the patient was tapered from medication, after being rendered euthyroid, a recurrence of hypercalcemia with rising iPTH levels occurred. PTH levels should be helpful in defining coexisting hyperparathyroidism in patients with thyrotoxicosis since in the latter iPTH is usually suppressed. Our findings support the recommendation that in patients suspected of having both hyperparathyroidism and hyperthyroidism, a diagnosis of the former can only be made with certainty after the patient has been rendered euthyroid with persistently elevated serum calcium and iPTH levels. While there are no clinical features which permit the easy identification of patients who present with dual lesions, the determination of iPTH values may be the most consistently helpful test initially, whereas other parameters such as vitamin D, serum phosphate are less reliable.

Hyperfunctioning Thyroid Adenoma Concomitant with Papillary Thyroid Carcinoma, Follicular Thyroid Adenoma and Primary Hyperparathyroidism.

“…It has also been suggested that relative decrease in calcitonin in thyrotoxicosis stimulates parathyroid hormone production [11]. Some reports have therefore recommended observation of the serum levels of calcium and PTH until the patient becomes euthyroid due to antithyroid therapy [11,27]. We were unable to have an observation period since rapid growth of the thyroid nodule in our patient necessitated immediate surgical treatment.…”

Hypercalcemic Crisis due to Primary Hyperparathyroidism Occurring Concomitantly with Graves' Disease

“…The coexistence of hyperparathyroidism and thyrotoxicosis was considered to be rare in the past (6,14). However, Abboud et al reported the coexistence of thyrotoxicosis in 13 of 96 (13.5%) patients admitted for surgery for hyperparathyroidism (6).…”

Abordagem clínico-laboratorial no diagnóstico diferencial de hipercalcemia

“…A hipercalcemia associada à tireotoxicose pode ocorrer em 2-5% destes pacientes e seria decorrente principalmente de um aumento da reabsorção óssea (52). Na maioria dos casos, a hipercalcemia é assintomática e normaliza com o eutiroidismo (52,53).…”

“…Na maioria dos casos, a hipercalcemia é assintomática e normaliza com o eutiroidismo (52,53). No entanto, associação de HPT primário com tireotoxicose pode ocorrer, embora pouco freqüente (<1% casos) (54).…”