The Role of Magnesium in Post-thyroidectomy Hypocalcemia

Effects of magnesium supplementation on post-thyroidectomy hypocalcemia: a prospective single-center study

BACKGROUND

Severe and/or symptomatic hypocalcemia due to hypoparathyroidism is the main contraindication for discharge in patients who have undergone thyroid surgery. Hypomagnesemia may contribute to the onset of hypoparathyroidism and is frequently observed after thyroid surgery in hypocalcemic patients. The impact of prophylactic and postoperative Magnesium supplementation on postoperative hypocalcemia and hypomagnesemia was prospectively evaluated by comparing patients undergoing prophylactic supplementation to a control group of patients who had only received magnesium after evidence of postoperative hypomagnesemia.

METHODS

One hundred and twenty patients who underwent a total thyroidectomy participated in the study. Seventy-three patients were included in the study group, 47 in the control group. Prior to surgery, patients in the study group were given magnesium orally for 5 days; postoperatively, calcium and magnesium was administered to all patients who displayed hypocalcemia and hypomagnesemia.

RESULTS

Postoperative biochemical hypocalcemia (serum calcium <8.5 mg/dL, regardless of its clinical severity) was found in 60 patients (50%) on D1 and in 58 patients (48.4%) on D2. Among hypocalcemic patients, hypomagnesemia was recorded in 29 at D1 (48%), and in 46 at D2 (79%). A significant positive correlation was found between magnesium, calcium, and parathyroid hormone in the first two postoperative days, while a significant inverse correlation occurred for these same parameters and length of hospital stay (P<0.001). One hundred and five patients (87.5%) were discharged as expected on the second postoperative day (65 in the study group, 40 in the control group, P=0.724), whereas 15 patients (12.5%) required prolonged hospitalization (eight in the study group, seven in the control group, P=0.721). The Study group only showed significantly higher magnesium levels on the first postoperative day (P=0.03).

CONCLUSIONS

Although magnesium and calcium levels showed the same trend after thyroidectomy, neither Magnesium prophylaxis nor Magnesium treatment influenced the clinical course of postoperative hypocalcemia.

Risk factors for postoperative hypocalcemia following total thyroidectomy: a retrospective study

BACKGROUND

and Objectives: Hypocalcemia is a commonly reported complication after thyroid surgery. Many possible risk factors have been identified. The purpose of this study is to analyze various risk factors possibly associated with development of postoperative hypocalcemia after thyroid surgery by dividing the sample population into postoperative hypocalcemia and normal calcium groups.

DESIGN

Retrospective.

SETTING

Multiple centers in the Makkah region of Saudi Arabia.

PATIENTS AND METHODS

Risk factors for postoperative hypocalcemia that were obtained for analysis include patient factors, perioperative blood parameters factors, disease-related factors, and surgical factors. Postoperative hypocalcemia was defined as a reduction of the total calcium level to <8.0 mg/dL. Hypocalcemic and normocalcemic patients were compared by multivariate logistic regression.

MAIN OUTCOME MEASURES

Distinguish independent risk factors for postoperative hypocalcemia after thyroidectomy.

SAMPLE SIZE

215 patients.

RESULTS

The incidence of hypocalcemia was 52.1% (112 of 215 patients). According to multivariate analysis, statistically significant risk factors for predicting postoperative hypocalcemia included postoperative parathyroid hormone level <10 pg/dL, inadvertent parathyroid gland resection, and neck dissection surgeries.

CONCLUSION

The causes of postoperative hypocalcemia are multi-factorial. Because many of these factors are modifiable, they should be identified postoperatively to distinguish high-risk groups and implement early preventive measures.

LIMITATIONS

Retrospective with a relatively small size. We encourage additional prospective studies with a larger sample size in multiple regions of the country, which might reveal further significant results.

Preoperative Vitamin D and Calcium Administration in Patients Undergoing Thyroidectomy: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Objective

This systematic review and meta-analysis aimed to assess whether preoperative administration of calcium and vitamin D prevents postoperative hypocalcemia.

Data Sources

A computerized search in Medline, Embase, and CENTRAL databases was performed.

Review Methods

Trials comparing preoperative calcium and vitamin D administration with either placebo or nothing were eligible for inclusion. The primary outcomes were the occurrence of laboratory hypocalcemia, mean postoperative calcium level, and symptomatic hypocalcemia. The secondary outcomes were the development of permanent hypoparathyroidism and length of hospitalization. Continuous outcomes were represented as standardized mean difference (SMD), and dichotomous outcomes were represented as risk ratio (RR).

Results

Nine trials that enrolled 1079 patients were found eligible. Postoperative laboratory hypocalcemia occurred less in patients who received preoperative calcium and vitamin D, but it was not statistically significant (RR = 0.77, 95% CI: 0.60-1.00; P = .05). Mean postoperative calcium level was significantly higher in the intervention group (SMD = 0.10, 95% CI: 0.07-0.12; P < .00001). The number of patients with symptomatic hypocalcemia was significantly lower in the intervention group (RR = 0.54, 95% CI: 0.38-0.76; P = .0005). There was no significant difference between the 2 groups in cases of permanent hypoparathyroidism and length of hospitalization.

Conclusion

Administration of calcium and vitamin D preoperatively achieves lower rates of postthyroidectomy symptomatic hypocalcemia in comparison with no intervention.

Association of Hypocalcemia and Magnesium Disorders With Thyroidectomy in Commercially Insured Patients

Importance

Hypocalcemia is a common complication of total thyroidectomy.

Objectives

To identify factors associated with hypocalcemia after total thyroidectomy and to explore the association between hypocalcemia, magnesium disorders, and costs of care.

Design, Setting, and Participants

A retrospective cross-sectional analysis was performed using data from the MarketScan Commercial Claim and Encounters database on 126 766 commercially insured patients younger than 65 years undergoing total thyroidectomy between January 1, 2010, and December 31, 2012. Statistical analysis was performed from January 1, 2016, to May 30, 2019.

Main Outcomes and Measures

Short- and long-term hypocalcemia and the costs of care were examined using multivariable regression modeling.

Results

Among the 126 766 patients in the study (81.6% women; mean age, 46.5 years [range, 18-64 years]), postoperative hypocalcemia was present in 19.1% of patients in the initial 30-day postoperative period and in 4.4% of patients at 1 year. Magnesium disorders were present in 2.1% of patients at the time of surgery. Short- and long-term hypocalcemia were significantly more likely in women (short-term: odds ratio [OR], 1.39 [95% CI, 1.29-1.50]; long-term: OR, 1.69 [95% CI, 1.52-1.89]), those younger than 40 years (short-term: OR for ages 40-64 years, 0.83 [95% CI, 0.78-0.87]; long-term: OR for ages 40-64 years, 0.73 [95% CI, 0.67-0.79]), those with a diagnosis of thyroiditis (short-term: OR, 1.48 [95% CI, 1.16-1.89]; long-term: OR, 1.60 [95% CI, 1.13-2.26]) or cancer (short-term: OR, 1.32 [95% CI, 1.05-1.67]; long-term: OR, 1.17 [95% CI, 0.83-1.63]), vitamin D deficiency (short-term: OR, 1.96 [95% CI, 1.74-2.21]; long-term: OR, 3.72 [95% CI, 3.30-4.18]), concurrent lateral neck dissection (short-term: OR, 1.51 [95% CI, 1.37-1.66]; long-term: OR, 1.95 [95% CI, 1.69-2.26]), concurrent central neck dissection (short-term: OR, 1.15 [95% CI, 1.07-1.24]; long-term: OR, 1.25 [95% CI, 1.12-1.40]), intraoperative parathyroid (short-term: OR, 1.58 [95% CI, 1.46-1.71]; and long-term: OR, 2.05 [95% CI, 1.82-2.31]) or recurrent laryngeal nerve injury (short-term: OR, 1.49 [95% CI, 1.27-1.74]; long-term: OR, 2.04 [95% CI, 1.64-2.54]), and magnesium disorders (short-term: OR, 8.40 [95% CI, 7.21-9.79]; long-term: OR, 25.23 [95% CI, 19.80-32.17]). Compared with the initial postoperative period, the odds of hypocalcemia decreased by 90.0% (OR, 0.10 [95% CI, 0.09-0.11]) at 6 months and 93.0% (OR, 0.07 [95% CI, 0.06-0.08]) at 1 year. After controlling for all other variables, magnesium disorders were associated with the highest odds of short- and long-term postoperative hypocalcemia. Hypocalcemia ($3392) and magnesium disorders ($14 314) were associated with increased mean incremental 1-year costs of care.

Conclusions and Relevance

Hypocalcemia is common after total thyroidectomy but resolves in most patients by 1 year. Magnesium disorders are significantly independently associated with short- and long-term hypocalcemia and are associated with greater costs of care. These data suggest a potentially modifiable target to reduce the incidence and cost of long-term hypocalcemia at patient and systemic levels.

Magnesium: The recent research and developments

Magnesium is the fourth most abundant mineral in the human body, which facilitates more than 300 enzymatic reactions. Magnesium is essential for nucleic material and protein synthesis, neuromuscular conduction, cardiac contractility, energy metabolism, and immune system function. Gastrointestinal system and kidneys closely regulate magnesium absorption and elimination to maintain adequate storage of magnesium. Magnesium deficiency has been linked to many diseases and poor health outcomes. Magnesium has also been proven to be an effective therapeutic agent in many diseases, such as bronchial asthma, cardiac arrhythmia, and pre-eclampsia.

The Effect of Hypomagnesemia on Refractory Hypocalcemia after Total Thyroidectomy: A Single-Center Prospective Cohort Study

BACKGROUND

Hypomagnesemia is known to impede hypocalcemia correction. This prospective observational study aimed to evaluate the impact of serum magnesium levels on the development of refractory hypocalcemia, which remains a concerning problem after total thyroidectomy (TT).

SUBJECTS AND METHODS

Consecutive subjects (n = 312; mean age = 38.4 [range: 13-83] years; M:F = 62:250) undergoing TT for benign or malignant thyroid diseases were evaluated for serum corrected-calcium (8.4-10.4 mg/dL), magnesium (1.7-2.4 mg/dL), intact parathormone (iPTH), and 25-hydroxycholecalciferol (25OHD) levels preoperatively, at 48-h and 6-month post-TT.

RESULTS

Postoperatively, 98 subjects (31.4%) exhibited transient hypocalcemia, 96 (30.8%) had hypomagnesemia, and 52 (16.7%) had refractory hypocalcemia. Preoperatively, 38 subjects (12.2%) had asymptomatic hypocalcemia and 77 (24.7%) had hypomagnesemia. In multivariate logistic regression analysis, independent risk factors of transient hypocalcemia were hyperthyroidism (odd's ratio [OR]: 5.6), 48-h iPTH (OR: 3.2), 48-h magnesium (OR: 2.7), preoperative 25OHD (OR: 0.96), and preoperative calcium (OR: 0.5; each P < 0.01). In receiver-operating characteristic analysis, percent calcium decline and 48-h magnesium reliably predicted transient hypocalcemia with a threshold of 10.5% and 1.9 mg/dL, respectively. Area under curve, sensitivity, and specificity were 0.822, 82.7%, and 72.9%; and 0.649 (each P < 0.001), 68.4%, and 63.1%, respectively.

CONCLUSION

Serum magnesium below 1.9 mg/dL had 2.7 times higher odds of developing transient hypocalcemia post-TT. Hypomagnesemia and percent calcium decline >10.5% within 48-h post-TT are associated with refractory hypocalcemia, which necessitates correction of both the deficiencies for prompt resolution of symptoms.

Predictors of post-thyroidectomy hypocalcaemia: a systematic and narrative review

OBJECTIVE

Hypocalcaemia is the most common complication after total or completion thyroidectomy. This study assesses recent evidence on predictive factors for post-thyroidectomy hypocalcaemia in order to identify the patients affected and aid prevention.

METHOD

Two authors independently assessed articles and extracted data to provide a narrative synthesis. This study was an updated systematic search and narrative review regarding predictors of post-thyroidectomy hypocalcaemia using the Ovid Medline, Embase, Cochrane and Cinahl databases. Results were limited to papers published from January 2012 to August 2019.

RESULTS

Sixty-three observational studies with a total of 210 401 patients met the inclusion criteria. The median incidence was 27.5 per cent for transient biochemical hypocalcaemia, 12.5 per cent for symptomatic hypocalcaemia and 2.2 per cent for permanent hypocalcaemia. The most frequent statistically significant predictor of hypocalcaemia was peri-operative parathyroid hormone level. Symptomatic hypocalcaemia and permanent hypocalcaemia were seen more frequently in patients undergoing concomitant neck dissection.

CONCLUSION

Many factors have been studied for their link to post-thyroidectomy hypocalcaemia, and this study assesses the recent evidence presented in each case.

EFFECT OF POST-SURGICAL RAI THERAPY ON PARATHYROID FUNCTION IN PATIENTS WITH DIFFERENTIATED THYROID CANCER

Objective: Radiotherapy with radioactive iodine (RAI) has become a common treatment for postsurgical differentiated thyroid carcinoma (DTC). The objective of this study was to determine the effect of RAI therapy following surgery on the function of the parathyroid glands in DTC patients. Methods: A total of 81 DTC patients who received RAI therapy after surgery were enrolled in the study. The size of the residual thyroid was detected by technetium-99m (^99mTc)-pertechnetate thyroid scan (^99mTc thyroid scan) before RAI therapy. The iodine uptake ability of residual thyroid was evaluated by iodine-131 (¹³¹I) whole-body scan (WBS). All patients were treated with an activity of 3.7 GBq (100 mCi) ¹³¹I. Parathyroid hormone (PTH), serum calcium, phosphorus, and magnesium were evaluated at 1 day before treatment, and at 1 month and 3 months after treatment. Results: The results show that there was no statistically significant difference in blood PTH level observed (P>.05) between 3 time points (pre-treatment, 1 month post-treatment and 3 months post-treatment). The serum calcium and phosphorus did not change significantly (P>.05), but serum magnesium level was elevated after treatment (P<.05). There were no significant differences between PTH changes and sex, age, scores of ^99mTc thyroid scan, scores of ¹³¹I WBS, Tumor (T) stage, and Node (N) stage. Conclusion: RAI therapy following surgery did not significantly affect parathyroid function in DTC patients. Abbreviations: ATA = American Thyroid Association; DTC = differentiated thyroid carcinoma; FT3 = free triiodothyronine; FT4 = free thyroxine; 131I = iodine-131; PTH = parathyroid hormone; RAI = radioiodine; 99mTc = Technetium-99m; TG = thyroglobulin; TNM = Tumor Node Metastasis; TSH = thyroid-stimulating hormone; WBS = whole-body scan.

Morbidity following thyroid surgery: acceptable rates and how to manage complicated patients

PURPOSE

The endocrine surgeon and the endocrinologist should standardize how they deal with patients with an indication for thyroidectomy, as the road to surgery starts well before the operation itself. The patient should be thoroughly informed about where and how surgery will be performed, the postoperative improvements that can be expected, and the possibility and incidence of relevant complications. This short review aims at identifying the most common postoperative issues after thyroidectomy, with the relevant therapeutic suggestions.

METHODS

A revision of studies reporting the morbidity of thyroid surgery, involving the largest numbers of patients.

RESULTS

It has been clearly demonstrated that the outcome of thyroid surgery is significantly better when the procedure is performed by an experienced surgeon. Thus, the number of thyroidectomies performed by a surgeon should drive the endocrinologist when referring a patient.

CONCLUSIONS

Despite the surgeon's experience, thyroidectomy is burdened by a relatively high rate of postoperative issues ranging from less severe ones to others causing significant changes in the patient's quality of life. Minor, non-invalidating symptoms have been described in 40% of patients after thyroidectomy (e.g. hoarseness, mild dysphagia, some degree of voice alteration); however, these symptoms usually resolve within a few months of surgery, with or without early treatment. On the other hand, major postoperative complications are observed in a limited number of patients, but in these cases early diagnosis is important to provide the most appropriate postoperative treatment, and thus hasten full recovery or at least achieve the greatest possible improvement.

Possible role of low magnesium levels in the onset of postoperative hypoparathyroidism following thyroidectomy

BACKGROUND

A positive correlation between calcium and magnesium serum levels is well known and depends upon various factors. This study aims at verifying the existence of this association in a retrospective series of patients who underwent thyroid surgery.

METHODS

Two hundred and eighty-five consecutive patients (202 female, 83 male, mean age 57 years) who underwent at least total thyroidectomy (TT) and had a complete clinical and biochemical pre- and postoperative evaluation were included in the study. Patients were evaluated with regard to: sex, age, indications for surgery, operative time, number of accidentally removed parathyroids, extent and time of surgery, thyroiditis, final histology, pre- and postoperative levels of calcium, magnesium, vitamin D, and creatinine, presence of symptoms of hypocalcemia. Statistical analysis was performed using the R software.

RESULTS

In the postoperative period, biochemical hypocalcemia (<8.5 mg/dL) was observed in 126 patients (44%) and severe hypocalcemia (<7.5 mg/dL, a level indicating the need for longer hospitalization) was seen in 40 (14%). When analyzing patients with and without postoperative hypocalcemia, the factors affecting postoperative biochemical hypocalcemia were: older age (P=0.019), longer operative time (P=0.039), and a highly significant correlation between postoperative calcium and magnesium levels (r=0.432; P<0.001).

CONCLUSIONS

The only factor among the ones we analyzed in this retrospective study that would appear to be linked to the onset of clinically relevant hypocalcemia is low magnesium levels in the postoperative period. A prospective randomized study with a group of patients undergoing magnesium replacement in the postoperative period can clarify the possible role of magnesium repletion on hypocalcemia.

Magnesemia: an independent risk factor of hypocalcemia after thyroidectomy

Background

This study was designed to investigate the impact of serum magnesium (Mg) levels on hypocalcemia after thyroidectomy.

Patients and methods

In total, 242 patients with differentiated thyroid cancer were retrospectively analyzed.

Results

Multivariate regression analysis showed hypomagnesemia was an independent risk factor for hypocalcemia (P<0.001). While Mg in low levels (0.66 mmol/L ≤ Po-Mg ≤0.74 mmol/L) increased the risk of hypocalcemia, postoperative serum Ca (Po-Ca) levels were significantly lower in patients with hypomagnesemia than in patients with normomagnesemia (P=0.01), and the former patients suffered significant decreases in serum Ca (P=0.02). Compared to patients with a mild decline of serum Mg after surgery (ΔMg <0.17), serum Ca decline significantly increased (P<0.001) in patients with a severe decline of serum Mg (ΔMg ≥0.17), while the change in amounts of parathyroid hormone (PTH) after surgery was similar between the two groups (P>0.05). In patients with normal Po-Ca levels, hypomagnesemia increased the risk of symptoms related to hypocalcemia by 4.478 times (OR =5.478, 95% CI 1.724–17.403).

Conclusion

Hypomagnesemia, or even a low serum Mg level within the normal range, can increase the risk of hypocalcemia. After excluding the potential effects of PTH on serum magnesium and calcium, serum Mg reduction is one of the most important factors that influences postoperative serum Ca reduction. What’s more, hypomagnesemia is closely linked with symptoms.

Preoperative vitamin D levels do not relate with the risk of hypocalcemia following total thyroidectomy. A cohort study

BACKGROUND

Hypocalcemia is the most common complication following total thyroidectomy. Few factors may relate with increased risk of postoperative hypocalcemia. Preoperative vitamin D values have been evaluated in few studies, but reports present conflicting data. Aim of our study is to evaluate the association of preoperative vitamin D values and hypocalcemia following total thyroidectomy.

METHODS

A retrospective analysis of patients undergoing total thyroidectomy in our department of endocrine surgery between November 2012 and November 2015 was performed.

RESULTS

Mean age of patients was 56.2 years (±14.0) and sex ratio (F:M) was 4.3:1. Sixty-four patients (17.4%) had preoperative vitamin D insufficiency (x<25 nmol/L), 138 patients (37.5%) vitamin D deficiency (25<x<50 nmol/L) and 166 patients (45.1%) vitamin D sufficiency (x>50 nmol/L). Following total thyroidectomy for both benign and malignant pathology, 66 patients (17.9%) had symptomatic hypocalcemia (x<2.0 mmol/L) requiring medical treatment (group 1), 64 patients (17.4%) biochemical hypocalcemia (2<x<2.1 mmol/L) not requiring treatment (group 2) and 238 patients (64.7%) had normal levels (x>2.1 mmol/L, group 3). Mean postoperative PTH value was 25.4 pg/ml (range 2-61). No statistical correlation between postoperative serum calcium and preoperative vitamin D values (R=-0.001, P=0.9849) was found nor associations were found regarding age, sex, type of thyroid disease or BMI.

CONCLUSIONS

In our cohort of patients, preoperative vitamin D levels were not associated with a higher risk of hypocalcemia following total thyroidectomy. Postoperative PTH appears to be the most sensible item to predict the risk of postoperative symptomatic hypocalcemia.

Incidence, prevalence and risk factors for post-surgical hypocalcaemia and hypoparathyroidism

Hypocalcaemia following thyroid surgery is common and is associated with significant short and long term morbidity. Damage to or devascularisation of parathyroid glands is the predominant underlying mechanism; although other factors such as hungry bone syndrome may occasionally contribute to it in the immediate post-operative period. The reported incidence of post-surgical hypocalcaemia and/or hypoparathyroidism (PoSH) varies significantly in the literature; the variation thought to be at least partly due to differences in the definitions used. Figures on the prevalence of chronic or long term post-surgical hypocalcaemia in the population are unclear. Risk factors for PoSH have been extensively studied in recent years and may be classified into patient, disease and surgery related factors. Some risk factors are modifiable; but both modifiable and non-modifiable factors help in generating a risk profile that may be used to select patients for preventative measures and/or changes in surgical strategy. This narrative review discusses recent literature on the incidence, prevalence and risk factors for PoSH.

Hypocalcaemia-induced tetany secondary to total thyroidectomy: a nursing case review

Presentations to the emergency department with a diagnosis of hypocalcaemia-induced tetany secondary to total thyroidectomy are rare. A patient presented to the emergency department of a regional Australian hospital with hypocalcaemia-induced tetany. A case study was employed to reflect on the care provided and identify knowledge practice deficits within this unusual patient presentation. Calcium plays a central role within the nervous system and is vital for both cardiac and muscular contraction. The clinical manifestations of electrolyte disturbances such as hypocalcaemia can be life threatening, and therefore, appropriate assessment, monitoring and management are essential to ensure positive patient outcomes. Understanding the importance of calcium imbalance for the emergency and critical care nurse is paramount in preventing complications associated with cardiac conduction and muscle tone, especially the potential for airway compromise. Education is central to this and may include clinical case reviews, the application of pathophysiological presentations of electrolyte imbalance and a review of electrolyte administration guidelines. Understanding the role of calcium within the body will assist emergency and critical care nurses to assess, monitor and intervene appropriately, thereby preventing the life-threatening manifestations of hypocalcaemia.

Hypomagnesemia predicts postoperative biochemical hypocalcemia after thyroidectomy

Background

To investigate the role of magnesium in biochemical and symptomatic hypocalcemia, a retrospective study was conducted.

Methods

Less-than-total thyroidectomy patients were excluded from the final analysis. Identified the risk factors of biochemical and symptomatic hypocalcemia, and investigated the correlation by logistic regression and correlation test respectively.

Results

A total of 304 patients were included in the final analysis. General incidence of hypomagnesemia was 23.36%. Logistic regression showed that gender (female) (OR = 2.238, p = 0.015) and postoperative hypomagnesemia (OR = 2.010, p = 0.017) were independent risk factors for biochemical hypocalcemia. Both Pearson and partial correlation tests indicated there was indeed significant relation between calcium and magnesium. However, relative decreasing of iPTH (>70%) (6.691, p < 0.001) and hypocalcemia (2.222, p = 0.046) were identified as risk factors of symptomatic hypocalcemia. The difference remained significant even in normoparathyroidism patients.

Conclusions

Postoperative hypomagnesemia was independent risk factor of biochemical hypocalcemia. Relative decline of iPTH was predominating in predicting symptomatic hypocalcemia.

Postoperative hypomagnesaemia is not associated with hypocalcemia in thyroid cancer patients undergoing total thyroidectomy plus central compartment neck dissection

BACKGROUND

The literature remains scarce and controversial regarding the association of hypomagnesaemia and hypocalcemia after total thyroidectomy. This study aims to assess this association in thyroid cancer patients underwent total thyroidectomy (TT) plus central compartment neck dissection (CCND).

METHOD

All consecutive thyroid cancer patients who underwent TT plus CCND were retrospectively reviewed through a prospectively collected database between October 2015 and June 2016 in a tertiary referral hospital. The univariate and multivariate analysis were performed to identify the significant predictors for hypocalcemia.

RESULTS

A total of 237 patients were included. The incidence of postoperative biochemical and symptomatic hypocalcemia was 52.3% (124 patients) and 33.8% (80 patients), respectively. Multivariate analysis showed that only postoperative hypoparathyroidism was an independent predictor for biochemical hypocalcemia (HR = 14.37, 95%CI = 6.07-34.0; P < 0.000), while parathyroid gland autotansplantation (HR = 2.02, 95%CI = 1.04-3.91; P = 0.038) and hypoparathyroidism (HR = 7.47, 95%CI = 3.84-14.5; P < 0.000) were independent risk factor for symptomatic hypocalcemia. Postoperative hypomagnesaemia was not significantly associated with the development of hypocalcemia (P > 0.05).

CONCLUSION

Postoperative hypomagnesaemia was not an independent predictor of hypocalcemia after total thyroidectomy. It seems to be unnecessary to routinely monitor the magnesium levels before and after thyroid surgery.