PTH and Hypocalcemia: Calcium is a critical electrolyte with essential intracellular and extracellular functions, and its serum concentrations are meticulously maintained within a narrow physiological range.1 The major factors determining calcium homeostasis are parathyroid hormone (PTH), ionized calcium, calcitriol, vitamin D, and serum phosphate levels.2 The predominant clinical symptoms and signs of hypocalcemia are related to neuromuscular irritability, which include perioral paresthesia, tingling sensations in the fingers and toes, and involuntary muscle contractions.