Abstract Purpose Postoperative hypoparathyroidism (HypoPT) is one of the most feared complications after thyroid surgery. In most cases, HypoPT is transient, requiring temporary substitution with calcium and active vitamin D. The analysis was conducted to investigate how calcium and vitamin D substitution was managed in routine postoperative clinical practice after discharge from hospital. Methods From March 2015 to December 2023, patients with HypoPT after thyroidectomy at the university medical center (UMC) Mainz, were included in a retrospective study. The rate of continued prescription of calcium and vitamin D by external practitioners in relation to the PTH and calcium levels at the first postoperative outpatient visit at the outpatient clinic of the UMC Mainz was analyzed and critically discussed. Results Ninety-four of 332 patients (28.3%) were continuously prescribed with calcium/vitamin D supplements: 14 had PTH deficiency and hypocalcemia and 14 had normal/elevated PTH levels with hypocalcemia, 59 had PTH values below the normal range and normo- or hypercalcemia and 7 had normal or elevated PTH levels with normocalcemia. Conclusions There are inconsistent procedures regarding the adjustment of the calcium and vitamin D substitution by the practices providing external follow-up treatment. To avoid iatrogenic suppression of PTH levels, high calcium load and potential affection of the kidney function, a reduction scheme should be actively recommended by thyroid surgeons.