Hypercalcemia can result from either hyperparathyroidism or non-parathyroid conditions. When hypercalcemia is accompanied by undetectable parathyroid hormone (PTH) levels, hyperparathyroidism is rarely considered the diagnosis. Herein, we report the case of a 65-year-old Caucasian woman referred to our hospital for further evaluation of hypercalcemia. Her symptoms included fatigue and brain fog, with undetectable PTH levels. A comprehensive workup, including a series of laboratory and imaging tests, excluded common non-parathyroid causes such as malignancy and familial hypocalciuric hypercalcemia. Ultrasound identified a likely enlarged parathyroid gland, which was further confirmed by a sestamibi scan. After 2 weeks of cinacalcet treatment, the patient's calcium levels decreased, indicating the parathyroid gland as the likely source of hypercalcemia. Parathyroidectomy was subsequently performed, revealing a 1927 mg adenoma. Postoperatively, the patient's calcium levels normalized, PTH levels became detectable within the normal range, and her symptoms resolved, with a marked improvement in energy. This case demonstrates that primary hyperparathyroidism can present with hypercalcemia and undetectable PTH. A genetic mutation in the PTH gene within the adenoma may explain the undetectable PTH levels preoperatively.
Keywords: Primary hyperparathyroidism; case report; cinacalcet; parathyroid; parathyroid hormone.
This case report discusses a 65-year-old woman who was found to have high calcium levels in her blood, a condition known as hypercalcemia. Typically, hypercalcemia can result from either a condition where the parathyroid glands produce too much parathyroid hormone (PTH) or from other non-parathyroid-related issues like cancer. However, when hypercalcemia occurs with undetectable levels of PTH, it is unusual for hyperparathyroidism to be the cause. In this patient’s case, she experienced symptoms like fatigue and brain fog, but her initial tests showed undetectable PTH levels. Further tests ruled out other common causes of high calcium, such as cancer or a genetic condition called familial hypocalciuric hypercalcemia. An ultrasound and a special scan called a sestamibi scan revealed an enlarged parathyroid gland, suggesting the presence of a parathyroid adenoma, a non-cancerous tumor. To confirm this, the doctors gave the patient a medication called cinacalcet, which is known to lower calcium levels if the parathyroid glands are involved. After two weeks of treatment, her calcium levels dropped, indicating that the parathyroid gland was indeed the source of the problem. The patient underwent surgery to remove the adenoma, which weighed nearly two grams. Following the surgery, her calcium levels returned to normal, and her PTH levels became detectable again within the normal range. Her symptoms, including fatigue, improved significantly, and she reported feeling more energetic. This case is unusual because it demonstrates that primary hyperparathyroidism can still be the cause of hypercalcemia even when PTH levels are initially undetectable. The doctors suspect that a genetic mutation in the adenoma might explain why PTH levels were undetectable before surgery. This case emphasizes the importance of thorough clinical evaluation, even when initial test results are not typical.
© The Author(s) 2024.