The Optimal Parathyroid Hormone Cut-Off Threshold for Early and Safe Management of Hypocalcemia After Total Thyroidectomy

The Impact of Calcium and Vitamin D Supplementation Prior to Thyroidectomy on Mitigating Postoperative Hypocalcemia

Background Hypocalcemia remains the most frequent complication after thyroidectomy. It can either be transient or permanent, and patients often find it unpleasant due to its association with prolonged hospitalization. The objective of this study was to determine the role of preoperative calcium and vitamin D supplementation in preventing hypocalcemia after subtotal/total thyroidectomy. Material and methods This quasi-experimental study was conducted at the Department of General Surgery, Ayub Teaching Hospital, Abbottabad, Pakistan, from January 2023 to July 2023. We utilized non-probability purposive sampling. Patients undergoing total thyroidectomy were recruited and followed until discharge to ascertain outcomes. They were divided into two groups: Group A received vitamin D (200,000 IU) one week preoperatively as single intramuscular dose and calcium (1 gm) orally two times daily for one week preoperatively, while Group B served as the control. Venous blood samples were taken post-surgery, on the second and seventh day and at day 30 to assess hypocalcemia. Chi-square test was employed, comparing hypocalcemia in both groups with a p-value ≤0.05 considered significant. Results One hundred thirty-two patients underwent subtotal/total thyroidectomy, with 46.2% (n = 61) being male and 53.8% (n = 71) female. The mean age of these patients was 37.12 ± 6.22 years, ranging from 20 to 50 years, and 57.6% (n = 76) were aged over 35 years. More than half (55.3%, n = 73) hailed from rural areas, while 4.7% (n = 59) resided in urban locales. Among the patients, 15.9% (n = 21) had a history of diabetes, and 24.2% (n = 32) were hypertensive. The mean body mass index (BMI) was 23.32 ± 2.41 kg/m2, with 7.6% (n = 10) classified as obese. The mean preoperative serum calcium level was 9.87 ± 1.07 mg/dL. Postoperatively, the mean serum calcium level was 8.74 ± 0.83 mg/dL. Both Group A (preoperative vitamin D and calcium supplementation) and Group B (control) demonstrated comparable baseline characteristics before undergoing thyroidectomy. The incidence of postoperative hypocalcemia was notably lower in Group A, with only 4.5% (n = 3) experiencing this complication. By contrast, 24.2% (n = 16) of patients in Group B, the control group, developed hypocalcemia (P = 0.001). Conclusion Our study supports the use of preoperative calcium and vitamin D supplementation in patients undergoing thyroidectomy to combat hypocalcemia. The treated group showed significantly lower hypocalcemia compared to the untreated group B. We recommend preoperative calcium and vitamin D supplementation for all thyroidectomy patients to reduce related morbidities and hospitalization duration.

A Parathyroid Hormone-guided Calcium and Calcitriol Supplementation Protocol Reduces Hypocalcemia-related Readmissions Following Total Thyroidectomy

OBJECTIVE

To determine the effect of a 4 hour postoperative serum parathyroid hormone (PTH) guided calcium and calcitriol supplementation protocol on the incidence of hypocalcemia and hospital readmissions in patients undergoing total thyroidectomy.

METHODS

This was a single institution, retrospective chart review of patients who underwent total thyroidectomy, 148 had been operated on prior to the protocol implementation and 389 after. Hypocalcemia risk was stratified as low (PTH >30 pg/ml), medium (15-30 pg/ml), and high (<15 pg/ml), using serum PTH values obtained 4 hours postoperatively. Hypocalcemia was defined as a total serum calcium level <8 mg/dl. Baseline demographic and operative characteristics, and postoperative outcome were recorded for both groups. Fisher's exact test or Wilcoxon rank sum test were used to compare the characteristics of the two groups. A multivariable logistic regression model was applied to account for potentially confounding variables.

RESULTS

Postoperative hypocalcemia occurred significantly less frequently in the protocol group compared to the preprotocol group (10.3% vs. 20.9%, P=.002). The reduction in hypocalcemia in the protocol group was observed both in patients with (16.3% vs. 25.6%) and without (8.4% vs. 19.3%) cervical lymph node dissection. There was a significantly lower incidence of hospital readmission events in the protocol group compared to the preprotocol group (1.0% vs. 4.7%, P=.013).

CONCLUSIONS

Compared to a historical cohort, a PTH-guided protocol for calcium and calcitriol supplementation significantly reduces postoperative hypocalcemia and hospital readmission rates, in patients undergoing total thyroidectomy.

Definition and diagnosis of postsurgical hypoparathyroidism after thyroid surgery: meta-analysis

Background

Postsurgical hypoparathyroidism (PH) is the most frequent complication after thyroid surgery. The aim of this systematic review and meta-analysis is to summarize a unifying definition of PH and to elucidate the best possible approach for early detection of PH.

Methods

A systematic review of the literature according to the PICO framework using Embase, PUBMED and the Cochrane library was carried out on 1 December 2021 followed by analysis for risk of bias, data extraction and meta-analysis. All studies addressing the definition of postoperative hypoparathyroidism and/or diagnostic approaches for early detection and diagnosis were included. Case reports, commentaries, non-English articles, book chapters and pilot studies and reviews were excluded.

Results

From 13 704 articles, 188 articles were eligible for inclusion and further analysis. These articles provided heterogeneous definitions of PH. Meta-analysis revealed that postoperative measurements of parathormone (PTH) levels have a higher sensitivity and specificity than intraoperative PTH measurements to predict PH after thyroid surgery. None of the timeframes analysed after surgery within the first postoperative day (POD1) was superior to predict the onset of PH. PTH levels of less than 15 pg/ml and less than 10 pg/ml are both reliable threshold levels to predict the postoperative onset of PH. A relative reduction of mean(s.d.) PTH levels from pre- to postoperative values of 73 (standard deviation 11) per cent may also be predictive for the development of PH. The estimation of calcium levels on POD1 are recommended.

Conclusion

PH is best defined as an undetectable or inappropriately low postoperative PTH level in the context of hypocalcaemia with or without hypocalcaemic symptoms. PTH levels should be measured after surgery within 24 h. Both threshold levels below 10 and 15 pg/ml or relative loss of PTH before/after thyroid surgery are reliable to predict the onset of PH.

The Influence of Prophylactic Calcium and Magnesium Supplementation on Postoperative Quality of Life and Hypocalcemia After Total Thyroidectomy: Study Protocol for a Randomized Controlled Trial

Background: We want to investigate if a routine preoperative dietary supplementation of calcium and magnesium prior to thyroidectomy for nodular goiter and graves' disease can influence patients' outcome with regards to hypocalcemia associated symptoms and quality of life in order to reduce the risk of post-thyroidectomy hypocalcemia and to improve patient's quality of life.

Methods: The study will be conducted as a two-armed randomized controlled trial including patients scheduled for total thyroidectomy. Patients assigned to the intervention group will receive calcium carbonate and magnesium oxide starting 2 weeks preoperatively. Primary outcome is the postoperative quality of life measured by the ThyPRO-39 and EQ-5D questionnaires. Secondary outcome is the assessment of postoperative biochemical (calcium and PTH levels) and clinical hypocalcemia (symptoms as reported by the patient).

Discussion: A prophylactic dietary supplementation with calcium and magnesium, which could easily be implemented in the preoperative setting, could potentially help to avoid or reduce hypocalcemia-associated symptoms and improve quality of life. In the event of a positive outcome, this preoperative procedure can be an inexpensive way to prepare patients scheduled for thyroidectomy and can possibly reduce disease-specific costs by reducing the postoperative complication rate.

Clinical Trial Registration: DRKS00017195 in the German clinical trials register (Deutsches Register Klinischer Studien, DRKS) on the 22.05.2019.