Background
Postoperative hypoparathyroidism (hypoPT) is one of the most frequent complications following total thyroidectomy (TT). It occurs when the parathyroid glands are damaged or their function is impaired, leading to reduced parathyroid hormone (PTH) secretion and low calcium levels. Patients may experience fatigue, paraesthesia, muscle cramps and cognitive difficulties. In many cases the condition is transient, but a considerable proportion develop permanent hypoPT requiring lifelong calcium and vitamin D therapy. This places a substantial burden on patients, with reduced quality of life (QoL), negative effects on renal and cardiovascular health, and increased healthcare costs.

Current postoperative care is largely suboptimal. Standard practice is routine blood testing and supplementation for all TT patients, irrespective of individual risk. This “one-size-fits-all” approach may expose many patients to unnecessary procedures and hospital stays, while not sufficiently focusing on those at highest risk. Recent studies indicate that intraoperative PTH (ioPTH) is a promising early marker of parathyroid function, but its role in guiding management is still not clearly defined.

Studies
This PhD project aims to improve outcomes after TT by evaluating ioPTH as the basis for individualized postoperative care. It combines retrospective, prospective and randomized studies to build a robust foundation for risk-adapted management strategies.

Study 1
A retrospective cohort study including patients who underwent TT at Aarhus University Hospital within the past five years. The objectives are to determine the incidence of hypoPT and to identify risk factors such as comorbidities, surgical indication and body mass index.

Study 2
A prospective cohort study in which TT patients are followed to examine the association between the magnitude of ioPTH decline and patient-reported QoL. QoL is assessed using validated questionnaires (ThyPro39, SF-36, HPQ27) at baseline and during follow-up, providing insight into how intraoperative biochemical changes relate to patient experiences.

Study 3
Two randomized controlled trials:

• Patients with <75% ioPTH decrease are randomized to omission of routine postoperative blood tests during the first week versus standard monitoring. The hypothesis is that patients with preserved parathyroid function can be safely managed without early biochemical testing.
• Patients with >75% ioPTH decrease are randomized to early high-dose calcium and vitamin D supplementation versus standard care. The hypothesis is that intensified treatment in high-risk patients reduces symptoms and length of stay without increasing adverse events.

Across all studies, primary outcomes include postoperative calcium and PTH levels, incidence of transient and permanent hypoPT, and healthcare resource use. Secondary outcomes include patient-reported QoL, frequency of hypocalcaemia requiring intervention, and surgical complications.

Perspectives
By integrating results from retrospective analyses, prospective observation and randomized trials, this project seeks to generate comprehensive evidence for risk-adapted management of hypoPT after TT. The findings may reduce unnecessary procedures, optimise early treatment for high-risk patients and improve long-term outcomes, and are expected to inform future national and international clinical guidelines.