We present a case report of delayed calcium normalization after successful parathyroidectomy in a 38-year-old patient with PHPT.<h4>Methods</h4>Parathyroidectomy was performed, with evidence of a decrease in PTH levels of more than 50% in the first 24 hours postoperatively compared to presurgical PTH; however, despite curative parathyroidectomy, a delayed calcium normalization was evidenced, with hypercalcemia persistence up to 120 hours postoperatively.<h4>Results</h4>After the first month postoperatively, serum calcium remained normal. This evidence concerns the gene PTH and hypercalcemia disease.