Night Sweats as the Presenting Symptom of Primary Hyperparathyroidism

Background: Approximately 25–40% of patients report night sweats in the previous month during appointments with their primary care clinicians. The differential diagnosis for night sweats is broad, with hyperthyroidism, carcinoid syndrome, pheochromocytoma, medullary thyroid carcinoma, insulinoma, and acromegaly as established endocrine causes. We present a case of primary hyperparathyroidism (PHPT) in which the patient’s chief complaint was night sweats and resolution occurred after parathyroidectomy. Case. A 39-year-old female reported one-year of daily night sweats that required changes of clothes and bedding. She denied excessive daytime sweating, frequent palpitations, tremors, nightmares, rashes, fevers, chills, cough, headaches, dizziness, abdominal pain, diarrhea, disrupted menses, or unintentional weight loss. Vital signs and examination were unremarkable. Hypercalcemia (11.0 mg/dL, 8.6–10.3) was noted and confirmed by additional serum calcium measurements. Intact PTH ranged from 27–33 pg/mL (12–88), and 24 h urine calcium (258 mg) excluded familial hypocalciuric hypercalcemia (FHH). Parathyroid scintigraphy and neck ultrasound identified a left neck mass, and the patient underwent successful resection of a left inferior parathyroid adenoma. Hypercalcemia and night sweats initially resolved after surgery, but the patient returned six weeks later with recurrence of night sweats. Reevaluation was notable for serum calcium 10.4 mg/dL, phosphorus 2.4 mg/dL (2.5–5.0), and intact PTH 104 pg/mL. A right superior parathyroid adenoma was identified on repeat parathyroidectomy, and the patient experienced durable resolution of night sweats and hypercalcemia following her second parathyroid surgery. She was screened for multiple endocrine neoplasia type 1 (MEN1) due to multiple parathyroid tumors, though no known pathogenic menin gene variants were identified. Conclusions: A title/abstract search in PubMed linking “hyperparathyroidism” and “hypercalcemia” to “night sweats,” “sleep hyperhidrosis,” “sweating,” “hot flashes,” “hot flushes,” “diaphoresis” and “vasomotor symptoms” yielded only one relevant case of a postmenopausal woman with hot flushes unresponsive to hormone replacement that resolved after parathyroidectomy for PHPT. Hypercalcemia is known to affect central nervous system function. It is possible that in rare cases hypercalcemia alters function of the medial preoptic area, lowering the temperature threshold above which peripheral vasodilatation and perspiration occur to dissipate heat. The patient’s predisposition to only night sweats is unclear, though unlike the first patient reported with PHPT and sweating, our patient is premenopausal. This case indicates that vasomotor symptoms may occur with PHPT and resolve after successful parathyroid surgery.