Saudi Surgical Journal

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 9  |  Issue : 2  |  Page : 34--39

Hypocalcemia following thyroid surgery- A prospective study


Sidharth Sabu Cherian 
 Department of Minimal Access Surgery, Dr. KM Cherian Institute of Medical Sciences, Chengannur, Kerala, India

Correspondence Address:
Sidharth Sabu Cherian
Department of Minimal Access Surgery, Dr. KM Cherian Institute of Medical Sciences, Chengannur, Kerala
India

Abstract

Introduction: This was a prospective observational study of 18-month duration. The purpose of this study is to compare preoperative serum calcium levels with postoperative serum calcium levels and to analyze postthyroid surgery hypocalcemia with regard to prevalence, clinical presentation, and severity and to treat hypocalcemia if it occurs. In addition, we analyzed the correlation of postoperative hypocalcemia with relation to the type of surgery, diagnosis, duration of surgery, and the quantity of blood loss. This study was conducted on consecutive patients who underwent thyroid surgery in the Department of General Surgery of a tertiary hospital in Puducherry for 18 months from November 2014 to April 2016. The median age of the patients was 40 years. The sex ratio was 17:2 in favor of females. Out of 38 patients, 18 patients were diagnosed with multinodular goiter, 8 were follicular carcinoma thyroid, 5 were papillary carcinoma thyroid, 2 were medullary carcinoma thyroid, 4 were adenomatoid nodule, and 1 patient was diagnosed to have thyroid abscess. In addition, 31 patients underwent total thyroidectomy, 6 patients underwent hemithyroidectomy when 1 patient underwent incision and drainage for thyroid abscess. Results: 39% (n = 15) of the patients developed hypocalcemia postoperatively. 87% (n = 11) of the patients were symptomatic and required calcium correction. Two patients had delayed presentation of hypocalcemia on postoperative day 5. One patient who underwent hemithyroidectomy developed hypocalcemia in the postoperative period. Trousseau's sign was the most typical clinical feature seen in hypocalcemia patients. In the present study, no significant association of hypocalcemia with the female gender was noted, and we did not find any association of hypocalcemia with advancing age. We did not find any association between hypocalcemia and prolonged surgery duration or increased blood loss in the present study. In addition, we did not see any increase in the incidence of hypocalcemia in patients who underwent thyroidectomy combined with lymph node clearance. Conclusion: The rate of postoperative hypocalcemia following thyroid surgery in this study was 39%. It coincides with the incidence reported elsewhere in the world. Although the risk of hypocalcemia was associated with increased blood loss, prolonged surgery, and extent of surgery, it was not statistically significant. If a similar study is conducted on a larger scale, including a broader spectrum of the population, important factors that influence postoperative hypocalcemia may be recognized.



How to cite this article:
Cherian SS. Hypocalcemia following thyroid surgery- A prospective study.Saudi Surg J 2021;9:34-39


How to cite this URL:
Cherian SS. Hypocalcemia following thyroid surgery- A prospective study. Saudi Surg J [serial online] 2021 [cited 2022 Jul 3 ];9:34-39
Available from: https://www.saudisurgj.org/text.asp?2021/9/2/34/345197


Full Text



 Introduction



Postoperative hypocalcemia is the most common complication after total thyroidectomy, although vocal cord palsy and postoperative bleeding are more clinically apparent. The incidence of hypocalcemia following thyroid surgeries ranges from 1.7% to 68%.[1],[2],[3] The clinical syndrome usually presents 24–48 h after surgery and requires strict monitoring. It could be the main factor determining the length of hospital stay after the surgery.[4],[5] It is usually mild, but sometimes, it may be severe. If it persists for 6 months or longer after surgery, then it is considered permanent hypocalcemia. Otherwise, it is called transient hypocalcemia. Patients must undergo close postoperative observation and laboratory evaluations. However, 0% to 33% of patients will experience permanent hypoparathyroidism.[2] The main reason for postoperative hypocalcemia is hypoparathyroidism, caused by injury or devascularization of a parathyroid gland, accidental removal of one or more parathyroid glands and hematoma formations. Many factors contribute to the increased incidence of hypocalcemia and hypoparathyroidism after thyroidectomy, like-total thyroidectomy, need for reoperations, combined neck dissection, preoperative hyperthyroidism, and inexperienced surgeons performing thyroidectomy.[6],[7]

There are many discussions in the literature regarding the role of parathormone in detecting postoperative hypocalcemia. Some studies have found that in postthyroidectomy patients with clinical symptoms of tetany, the concentration of PTH was indeterminable and much lower in hypercalcemic patients.[4],[5] However, there is only one official recommendation from the Australian Endocrine Surgeons Society in 2007, which advised measuring parathormone concentration as a means of postoperative hypocalcemia evaluation.[8] Hence postoperatively, we did not monitor serum parathormone levels [Figure 1] and [Figure 4], [Figure 5], [Figure 6].{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}

Since hospital stay is always extended if hypocalcemia develops, some surgeons advocate a policy of early discharge by treating all patients with calcium supplements, with or without Vitamin D supplements, regardless of they developing symptoms or not.[9] Unfortunately, this practice invariably results in many patients getting over treatment and could delay hypoparathyroidism diagnosis and appropriate treatment.[8],[10]

According to Becker et al., Chvostek's sign is no longer considered a reliable indicator of hypocalcemia since it only indicates neuromuscular irritability and is not a reliable indicator of hypocalcemia.[11] A study done by Fonseca OA mentions that 29% of patients with hypocalcemia (confirmed by laboratory reports) had a negative Chvostek's sign.[12] On the other hand, in his study, Hoffman E demonstrated a positive Chvostek's sign-in for nearly 25% of healthy individuals.[13] Becker et al. and Bushinsky DA mention in their research that, Trousseau's sign is both sensitive and specific for hypercalcemic tetany[11],[14] and according to Bushinsky DA, in patients with positive Trousseau's sign, the visual manifestations are apparent, and sometimes patients may also experience upper limb extremity paresthesia, fasciculation, or twitches.[14] Therefore, Trousseau's sign is more sensitive and specific for hypocalcemia than Chvostek's sign.

The purpose of this study was to compare preoperative serum calcium levels with postoperative serum calcium levels and to analyze postthyroid surgery hypocalcemia with regards to prevalence, clinical presentation, and severity and to treat hypocalcemia if it occurs. In addition, the correlation of postoperative hypocalcemia with respect to the type of surgery, the diagnosis, the duration of surgery, and the quantity of blood loss was also analyzed in our study.

 Materials and Methods



This was a prospective observational study of 18-month duration. This study was conducted on consecutive patients who underwent thyroid surgery in the Department of General Surgery in a tertiary hospital for 18 months. Patients aged more than 12 years, both men and women, were included in this study. If they had concomitant parathyroid diseases or were already on calcium supplementation, such patients were excluded from the study. The parameters studied were

  • Preoperative and postoperative serum calcium (corrected calcium)
  • Preoperative and postoperative magnesium level
  • Preoperative and postoperative phosphate level
  • Serum albumin level.


Methodology

During 18 months, 38 consecutive patients older than 12 years of age undergoing all thyroid surgeries were prospectively followed up, and they underwent analysis regarding postoperative hypocalcemia. The ethical committee approved the study, and all patients gave their informed consent to participate. The surgeries were performed by a team consisting of consultants and residents. Demographic and clinical characteristics of the patients were obtained using a structural proforma. All the patients were evaluated preoperatively with complete blood investigations, thyroid function tests, ultrasound study of the neck and thyroid and fine-needle aspiration cytology. In addition, specific blood investigations such as serum calcium levels, serum albumin levels, serum magnesium levels, and serum phosphorus levels were measured and documented preoperatively. In addition, operative details such as the extent of surgery, blood loss, the number of parathyroid glands identified, and the time duration of surgery were documented. Postoperatively, the patients were closely monitored for any clinical features suggestive of hypocalcemia, namely oral and perioral paresthesia, acral paresthesia, Trousseau's sign, Chvostek's sign, abnormal tendon reflexes, or laryngospasm. Serum calcium, magnesium, phosphorus, and albumin were checked and documented after 24 h on postoperative day 1.

Corrected calcium was calculated with the help of the formula:

Corrected (Ca2+) = Serum (Ca2+) + (0.8 × [4-Serum albumin])

Serum calcium, magnesium, phosphorus, and albumin were estimated again on postoperative day 5. If the serum corrected calcium level was <8.5 mg/deciliter at any of the above said times, such patients were deemed to have hypocalcemia.

 Results



A total of 38 patients who had undergone thyroid surgeries for various thyroid diseases were included in this study. The median age of the patients was 40 years. The sex ratio was 17:2 in favour of females. Patients with different thyroid diseases were included in this study. Out of 38 patients, 18 patients were diagnosed to have a multinodular goiter, 8 were follicular carcinoma thyroid, 5 were papillary carcinoma thyroid, 2 were medullary carcinoma thyroid, 4 were adenomatoid nodule, and 1 patient was diagnosed to have thyroid abscess. 31 patients underwent total thyroidectomy, 6 patients underwent hemithyroidectomy, and 1 patient underwent incision and drainage for thyroid abscess. We identified at least 2 parathyroid glands in 34 patients.

Incidence of hypocalcemia

Thirty-nine percent (n = 15) of the patients developed hypocalcemia postoperatively [Figure 2].

Confidence internal- ±15.5.

Out of 25 patients with age ≤45 years, 7 patients developed hypocalcemia. Out of 13 patients with age more than 45 years, 8 developed hypocalcemia. The mean value of preoperative corrected calcium was 9.1 mg and, at the time of discharge, was 9 mg. Symptomatic hypocalcemia was seen in 13 patients. Delayed presentation of hypocalcemia was noted in 2 patients (POD 5). 11 patients required oral calcium supplementation, and 2 patients required intravenous calcium supplementation. The most typical clinical sign elicited in hypocalcemia patients was Trousseau's sign (n = 11). Perioral paresthesia was noted in 4 patients. Chvostek's sign was elicited in 2 patients.

Hypocalcemia association with other clinical parameters

The risk of Hypocalcaemia was associated with 4 parameters like-increased blood loss, prolonged surgery, the type of surgery and diagnosis [Figure 3].

In 10 hypocalcemia patients, blood loss was more than 25 ml. Conversely, in 5 hypocalcemia patients, blood loss was ≤25 ml.

Five out of 15 hypocalcemia patients had prolonged surgery (duration more than 180 min.)

Out of 15 patients who developed hypocalcemia postoperatively, 14 patients underwent total thyroidectomy, and 1 patient underwent hemithyroidectomy. Out of 5 patients diagnosed with papillary carcinoma thyroid, 2 patients had undergone total thyroidectomy with unilateral modified neck dissection, and 1 patient had undergone central lymph node clearance. One patient in this group developed postoperative hypocalcemia on day 2.

Out of 15 patients who developed hypocalcemia postoperatively underwent surgery for benign diseases. 6 patients were operated on for malignant thyroid diseases.

 Discussion



No recent population studies are showing the prevalence of goiter in Tamil Nadu and Pondicherry. Our institutional statistics showed that 66% of thyroid surgeries are for benign diseases, comprising multinodular goiters, adenomatoid nodules, nodules with suspicious cytology, and recurrent goiters. In the present study, the mean value of preoperative corrected calcium was 9.089; on postoperative day 2, it was reduced to 8.7. On postoperative day 5, there was an increase in mean corrected calcium to 9.03. In similar studies done by Nair et al. and Noureldine et al., 30.36% and 29.9% of patients developed hypocalcemia in the immediate postoperative period, respectively.[15],[16] Another study by Shaha et al. had noted up to 50% of transient hypocalcemia after thyroidectomy.[17] In the present study, 34% (n = 13) of patients developed hypocalcemia on postoperative day 2. 29% (n = 11) of the patients had symptomatic hypocalcemia for which calcium correction was given. Among them 81% (n = 9) responded to oral calcium correction while 18% (n = 2) required intravenous calcium supplementation. In the present study, none of the patients developed permanent hypocalcemia. A study conducted by Nair et al. noted a 3-day delay in the presentation of hypocalcemia after thyroidectomy.[15] There are reports of late-onset hypocalcemia following thyroidectomy for Grave's disease.[18] In the present study, on postoperative day 5, 2 new patients were diagnosed with hypocalcemia; both had undergone total thyroidectomy, 1 female and 1 male patient, with the diagnosis of papillary carcinoma thyroid and follicular carcinoma thyroid, respectively. Baldassarre et al., in their meta-analysis, reported an incidence of 1.9% postoperative hypocalcemia in patients who underwent hemithyroidectomy.[19] In the present study, one patient developed hypocalcemia on postoperative day 2 among the six patients who had undergone hemithyroidectomy. It was a female patient, and she was operated on for an adenomatoid nodule. However, she did not have any symptoms of hypocalcemia. A study done by Noureldine et al. found that males had a 56% and 63% decreased risk of developing postoperative significant and mild hypocalcemia, respectively.[16] In the present study, among four men, all of them had undergone total thyroidectomy. Two of them had medullary carcinoma thyroid, one of them was diagnosed with follicular carcinoma thyroid and the other with papillary carcinoma thyroid. The patient diagnosed with papillary carcinoma thyroid developed hypocalcemia on postoperative day 2, it was severe, and he needed intravenous calcium correction. As mentioned above, the male patient diagnosed with follicular carcinoma thyroid developed delayed hypocalcemia on postoperative day 5. He was managed with oral calcium supplementation. Four patients who developed postoperative hypocalcemia were below 35 years of age, and five were above 50. No significant association of hypocalcemia with the female gender was noted in the present study. We did not find any association of hypocalcemia with advancing age, unlike some similar studies done by Abboud et al. and Bhattacharyya et al.[20],[21] In the present study, Trousseau's sign was the most common clinical feature observed in the patients who developed hypocalcemia. In 11 patients, Trousseau's sign was positive, whereas only 2 patients had positive Chvostek's sign. Nowadays, Chvostek's sign is no longer considered a reliable indicator of hypocalcemia since it only indicates neuromuscular irritability and is not a reliable indicator of hypocalcemia.[11] A study done by Fonseca showed that 29% of patients with hypocalcemia (confirmed by laboratory reports) had a negative Chvostek's sign.[12] Hoffman, in his study, demonstrated a positive Chvostek's sign-in for nearly 25% of healthy individuals.[13] On the other hand, Trousseau's sign is thought to be both sensitive and specific for hypercalcemic tetany.[11],[14] In positive Trousseau's sign, the visual manifestations are obvious, and sometimes, patients may also experience upper limb extremity paresthesia, fasciculation, or twitches.[14] Trousseau's sign is more sensitive and specific for hypocalcemia than Chvostek's sign. A study done by Ambe et al. on 305 patients showed that prolonged surgery or greater blood loss is not a surrogate marker for postoperative hypocalcemia following total thyroidectomy.[22] We did not find any association between hypocalcemia and prolonged surgery duration or increased blood loss in the present study. 64% (n = 7) of patients who developed hypocalcemia postoperatively did not have a prolonged surgery (duration <180 min), while 36% (n = 4) had a prolonged surgery (duration >180 min). In 39% of patients (n = 5) who developed hypocalcemia postoperatively, the blood loss was <25 ml, while 62% (n = 8) had blood loss of more than 25 ml. Puzziello et al. states that the rate of hypocalcemia following thyroid surgery is higher in patients who had undergone lymph node clearance than in the patients in which the lymph node clearance was not performed.[23] In the present study, out of five patients diagnosed with papillary carcinoma thyroid, two patients had undergone total thyroidectomy with unilateral modified neck dissection, and one patient had undergone central lymph node clearance. One patient in this group developed postoperative hypocalcemia on day 2. However, it was not statistically significant. However, we advise avoiding routine central neck dissection, at least in differentiated thyroid cancers, unless indicated.

 Summary



This study was conducted on consecutive patients who underwent thyroid surgery in the Department of General Surgery, Pondicherry Institute of Medical Sciences, Puducherry, for 18 months from November 2014 to April 2016. The median age of the patients was 40 years. The sex ratio was 17:2 in favour of females. Out of 38 patients, 18 patients were diagnosed with multinodular goiter, 8 were follicular carcinoma thyroid, 5 were papillary carcinoma thyroid, 2 were medullary carcinoma thyroid, 4 were adenomatoid nodule, and 1 patient was diagnosed to have thyroid abscess. 31 patients underwent total thyroidectomy, 6 patients underwent hemithyroidectomy when 1 patient underwent incision and drainage for thyroid abscess. 39% (n = 15) of the patients developed hypocalcemia postoperatively. 87% (n = 11) of the patients were symptomatic and required calcium correction. 2 patients had delayed presentation of hypocalcemia on postoperative day 5. 1 patient who underwent hemithyroidectomy developed hypocalcemia in the postoperative period. Trousseau's sign was the most typical clinical feature seen in hypocalcemia patients. In the present study, no significant association of hypocalcemia with the female gender was noted, and we did not find any association of hypocalcemia with advancing age. We did not find any association between hypocalcemia and prolonged surgery duration or increased blood loss in the present study. In the present study, we did not see any increase in the incidence of hypocalcemia in patients who underwent thyroidectomy combined with lymph node clearance.

 Conclusion



The rate of postoperative hypocalcemia following thyroid surgery in this study was 39%. It coincides with the incidence reported elsewhere in the world. Although the risk of hypocalcemia was associated with increased blood loss, prolonged surgery, and extent of surgery, it was not statistically significant. If a similar study is conducted on a larger scale, including a broader spectrum of the population, important factors that influence postoperative hypocalcemia may be recognized.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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