PTH and endocrine system disorder: Primary hyperparathyroidism (PHPT), caused by parathyroid adenoma in 84% and parathyroid hyperplasia in 15% of cases, is an endocrine disorder that induces metabolic dysregulation of calcium and phosphate owing to increased production and secretion of parathyroid hormone (PTH).[1] Typically, hypercalcemia in patients with PHPT leads to hypertension via systemic vascular contraction resulting from increased serum calcium levels.[2] However, we encountered a challenging case in which a patient with PHPT experienced severe hypotension after tracheal intubation.