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| ORIGINAL ARTICLE |
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| Year : 2022 | Volume
: 28
| Issue : 2 | Page : 174-177 |
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Hypocalcaemia following thyroid surgery in a tertiary care centre
Anusha Vadivelu, KN Vijayan, Liju Varghese
Department of General Surgery, KIMSHEALTH Hospital, Thiruvananthapuram, Kerala, India
| Date of Submission | 24-Nov-2022 |
| Date of Decision | 30-Nov-2022 |
| Date of Acceptance | 02-Dec-2022 |
| Date of Web Publication | 30-Jan-2023 |
Correspondence Address:
Dr. Anusha Vadivelu
Department of General Surgery, KIMSHEALTH Hospital, Thiruvananthapuram - 695 029, Kerala
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/ksj.ksj_47_22
Introduction: Hypocalcaemia may occur secondarily to surgical trauma, devascularisation, unintentional removal of parathyroid glands and ligation of both inferior thyroid arteries. The objective of the study was to evaluate the calcium level after thyroid surgery and to evaluate the clinical symptoms and signs of hypocalcaemia after thyroid surgery. Materials and Methods: Eighty-one patients were evaluated; post-operatively, the calcium levels were monitored and early hypocalcaemia was detected by looking for the symptoms and signs of hypocalcaemia. The calcium levels were recorded from post-operative day 1, 2, 3 and 7. By this method, low serum calcium levels are corrected by calcium supplements and can prevent the need of parental calcium. Results: The most common age group affected by thyroid disorders was 41–50 years and less common age group affected was above 60 years. Females (71.6%) were commonly affected by thyroid disorders compared to males (28.4%). Majority of the patients were diagnosed with multinodular goitre (42%), followed by papillary carcinoma (39.5%). Most of our study population underwent total thyroidectomy (around 90%). The number of patients who encountered carpodeal spasm was 1.2% Chovstek sign, trousseau sign, electrocardiogram changes were seen in 2.5% population Patients who received treatment for symptomatic hypocalcaemia was 2.5%. Conclusion: Females were more prone to hypocalcaemia compared to males. Hypocalcaemia was found to be more prevalent in those patients who underwent total thyroidectomy compared to other surgeries. This can be prevented by meticulous dissection, identification of parathyroid and serial monitoring of calcium levels. Our study also serves as a cost-effective tool for the general population and immediate intervention can be given to the patients who are at risk to become symptomatic and improve their quality of life.
Keywords: Hypocalcaemia, parathyroid, thyroidectomy
How to cite this article:
Vadivelu A, Vijayan K N, Varghese L. Hypocalcaemia following thyroid surgery in a tertiary care centre. Kerala Surg J 2022;28:174-7 |
| Introduction | |  |
Hypocalcaemia is a common biochemical abnormality that can be asymptomatic in mild cases to causing acute life-threatening crisis.[1] Hypocalcaemia after total thyroidectomy with or without neck dissection is the most common early complication. The incidence of transient hypocalcaemia is 30% and the incidence of permanent hypocalcaemia is <2%. Hypocalcaemia may occur secondarily to surgical trauma, devascularisation, unintentional removal of parathyroid glands and ligation of both inferior thyroid arteries. Thyroid carcinoma with or without neck dissection, large goitre, total thyroidectomy, recurrent goitre, primary hyperparathyroidism, toxic goitre, completion thyroidectomy and retrosternal goitre were found as the risk factors predisposing to hypocalcaemia after thyroidectomy. The recommended surgical strategy is the pre-operative assessment of serum calcium, meticulous dissection, identification, protection and preserving the blood supply of parathyroid glands if devascularisation of parathyroid is detected during surgery, parathyroid should be confirmed by frozen section and autotransplantation. Eighty per cent of superior and inferior parathyroid gland mainly supplied by inferior thyroid artery. Hence, ligation of the main trunk of the inferior thyroid artery is not practised now. A framework for safe thyroidectomy is critical, given that the complication rates following thyroidectomy are not insignificant (7.4%–13.8%).[2],[3]
Clinically, hypocalcaemia after thyroidectomy is the most common complication, with the reported incidence of transient and permanent hypocalcaemia ranging from 3% to 52% and 0.4% to 13%, respectively.[4],[5] Various methods were implemented for diagnosis and managing post-operative hypocalcaemia. The older approach of 2-day hospitalisation and monitoring of serum calcium levels after surgery is still being used by many institutions worldwide because the keystone of hypocalcaemia typically occurs within 48 h after surgery.[6],[7] We accept that it is important to observe patients in the initial post-operative hours for haemorrhage and airway obstruction that may necessitate an immediate intervention to the operating room; however, calcium monitoring with hospitalisation beyond 24 h, in the absence of perioperative complications, is often unnecessary because patients typically experience only mild post-operative pain and rapidly return to baseline daily functionality. The routine use of post-operative oral calcium and/or Vitamin D supplementation has been advised by some surgeons to reduce the occurrence of hypocalcaemia and shorten hospital stays. This practice is common in the outpatient or short-stay setting, where there is a limited time facility to correct hypocalcaemia once it occurred. Others have advocated sending patients home with prescriptions for elemental calcium supplementation to be given if they develop the symptoms of hypocalcaemia.[8],[9]
| Materials and Methods | | |
The aim of the study was to evaluate the incidence of clinical and biochemical hypocalcaemia following thyroid surgery in our tertiary care centre. It was a prospective, observational study from February 2020 to March 2022 on all the patients above 18 years admitted under the department of general surgery and underwent total thyroidectomy for solitary nodular goitre, multi-nodular goitre, papillary carcinoma thyroid, follicular carcinoma thyroid, medullary carcinoma thyroid, Hurthle cell neoplasm and retrosternal goitre. Patients with primary secondary or tertiary hyperparathyroidism, previous irradiation to the neck, patients on calcium supplementation, those who had hemi thyroidectomy or lobectomy and those below18 years were excluded from the study.
Required sample size (n) was calculated using the formula:
The minimum sample size required for this study was 81. All patients undergoing thyroidectomy were included in this study after informed consent; data were collected from patients undergoing total thyroidectomies through meticulous history taking, careful clinical examination, appropriate radiological, haematological investigations including serum calcium, operative findings and follow-up of the cases after surgery with clinical signs and symptoms of hypocalcaemia. Serum calcium estimation was done by NM-BAPTA method. The collected data were analysed with IBM SPSS Statistics for Windows, Version 23.0.(Armonk, NY, USA: IBM Corp). To describe about the data, descriptive statistics frequency analysis and percentage analysis were used for categorical variables and the mean and standard deviation were used for continuous variables. To find the significant difference in the multivariate analysis for repeated measures, the repeated measures ANOVA was used with Bonferroni correction to control the type I error on multiple comparison. In the above statistical tool, the probability value <0.005 was considered significant level.
| Results | | |
Age distribution up to 30 years was 8 (9.9%), 31–40 years 19 (23.5%), 41–50 years 28 (34.6%), 51–60 years 22 (27.2%) and above 60 years 4 (4.9%), and the average age of the study population was 45 ± 11 years; in gender wise, 58 (71.6%) were female and 23 (28.4%) were male. Diagnosis consisted of papillary carcinoma in 32 (39%), follicular 4 (4.9. %), MNG 34 (42.0%), retrosternal 1 (1.2%), solitary nodular 9 (11.1%) and colloid goitre 1 (1.2%).
Seventy-three (90.1%) of 81 underwent total thyroidectomy, 5 (6.2%) underwent hemi thyroidectomy and 3 (3.7%) near total thyroidectomy. Out of the patients, 1 (1.2%) presented with perioral numbness, 2 (2.5%) with carpopedal spasm, 2 (2.5%) with Chvostek sign, 2 (2.5%) with Trousseau sign, 2 (2.5%) with electrocardiogram changes and 2 (2.5%) presenting with treatment.
Calcium comparison from the baseline to post-operative day 7 was highly statistically significant with P = 0.0005 < 0.01 level and the pairwise comparison shows the highly statistical significance between the baseline with day 3, post-operative day 2 with day 3 P = 0.002 < 0.01 and between post-operative day 3 with day 7 P = 0.0005 < 0.01 whereas other pairs showed no statistical significance [Table 1] and [Table 2].
The comparison of post-operative 1st and 7th days outcomes with age distribution using Pearson's Chi-Square test showed no statistical significant with Chi-square value = 1.305, P = 0.615 > 0.05 level at 1st day, similarly at 7th days too no statistical significant with Chi-Square value = 2.665, P = 0.860 > 0.05 level [Figure 1]. | Figure 1: Comparison of Post-operative 1st and 7th day's outcome with age distribution by Pearson Chi-square test
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Comparison of post-operative 1st and 7th days outcomes with gender distribution using Fisher's exact test, which shows no statistical significant with Chi-square value = 1.669, P = 0.573 > 0.05 level at 1st day, similarly at 7th days too no statistical significant with Chi-Square value = 0.037, P = 1.000 > 0.05 level [Figure 2]. | Figure 2: Comparison of Post-operative 1st and 7th day's outcome with Gender distribution by Fisher's exact test
Click here to view |
| Discussion | | |
The study shows that out of 81 patients who underwent thyroid surgeries, 58 patients were female and 23 patients were male, and on comparison, it showed that hypocalcaemia was seen only in the female population in the post-operative period; hence, there is no statistical significance. Low calcium levels only in females can be due to less male patients taken into study.
Noureldine et al.[10] discovered that out of 304 patients, post-operative mild hypocalcaemia occurred in 68 (22.4%) patients and 91 (29.9%) patients had at least 1 serum calcium level of less than 8.0 mg/dl and 22 (24%) developed hypocalcaemia related symptoms. Post-operative permanent hypocalcaemia was encountered in only two patients (0.7%); both were females and they developed significant immediate post-operative hypocalcaemia. They concluded low post-operative IPTH level, female sex and presence of malignant neoplasm are all significant, independent predictors of hypocalcaemia after total thyroidectomy. Clinicians should consider these variables when deciding how to best manage or prevent post-operative hypocalcaemia.
Eismontas et al.[11] concluded that optimisation of the surgical technique could prevent the early incidence of hypocalcaemia after total thyroidectomy in some cases, and in other cases, identification of known risk factors post-operatively could help in early detection and effective treatment of these patients.
In the present study, out of 81 patients, 2.5% showed symptoms and signs of hypocalcaemia. The gender and age were compared with the calcium levels in post-operative day to look for any association. The results showed that there is no correlation with the calcium levels with respect to age and gender.
Del Rio et al.[12] found that sex (female gender is a strong risk factor), surgical procedure and perioperative changes in serum calcium are the only factors (among all variables examined) that influence early hypocalcaemia development.
Wang et al.[13] revealed that gender (P = 0.014), lateral lymph node dissection (P = 0.038), operation type (P < 0.001), operative time (P < 0.001) and applying CNs (P = 0.001) had a significant correlation with post-operative hypoparathyroidism. Female patients were vulnerable to post-operative hypoparathyroidism. Serum calcium is regulated by 1,25-dihydroxyvitamin D or calcitriol through bone resorption, PTH through calcium reabsorption of renal tubules and calcitriol through calcium intestinal absorption. This phenomenon may be attributed to the dropping hormone levels in menopausal women. Previous studies also showed that intrathyroidal parathyroid glands were more frequent in women owing to the high occurrence rates of parathyroid injury and hypocalcaemia.
The main strength of the study is that it was a prospective study and the blood investigation is a cost effective tool. Careful monitoring of serial calcium levels is an efficient way to detect hypocalcaemia in post thyroidectomy patients acts as a prophylactic measure to prevent parenteral administration of calcium and improves the quality of life.
The limitation of this study is the lack of follow-up after 1 week and only 81 patients were evaluated. This sample may not be an exact representation of the general population. A multicentre study with a higher sample size may offer a better clinical implication.
| Conclusion | | |
The present study concludes that middle age group between 41 and 50 years was commonly diagnosed with thyroid malignancy and females were more prone to hypocalcaemia compared to males. Out of 81 patients, only 2.5% of the population showed symptoms and signs of hypocalcaemia. Hypocalcaemia was found to be more prevalent in those patients who underwent total thyroidectomy compared to other surgeries. The probable reason can be due to decreased vascularity to the parathyroid during ligation of thyroid pedicles. This can be prevented by meticulous dissection, identification of parathyroid and serial monitoring of calcium levels, so that early detection can prevent the adverse events caused due to hypocalcaemia and reduces treatment cost. This also serves as a cost-effective tool for the general population and immediate intervention can be given to the patients who are at risk to become symptomatic and improve their quality of life.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]
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