|Year : 2021 | Volume
| Issue : 1 | Page : 23-26
Hypomagnesemia following thyroidectomy: Prospective observational - Pilot study
Amal Abdullah Abdulkareem
Department of Surgery, College of Medicine, King Saud University, King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia
|Date of Submission||03-Nov-2020|
|Date of Acceptance||14-Dec-2020|
|Date of Web Publication||14-Jun-2022|
Dr. Amal Abdullah Abdulkareem
Department of Surgery, College of Medicine, King Saud University, Riyadh
Kingdom of Saudi Arabia
Source of Support: None, Conflict of Interest: None
Background: Magnesium plays a role in the active transport of calcium (Ca+2) and potassium ions across cell membranes. Most of Mg+2 is intracellular or in the bone <1% is in the blood serum. Post thyroidectomy, hypoparathyroidism leads to acute hypocalcemia that leads to hypomagnesemia. The relation of Ca+2 and magnesium (Mg+2) metabolism is complex and mainly related to the interaction of these cations with parathyroid hormone (PTH) post thyroidectomy. Magnesium is an essential regulator of Ca+2 flux and intracellular action of Ca+2. Hypomagnesemia impairs hypocalcaemia-induced PTH release, which is corrected rapidly after magnesium replacement. Attempting to correct only hypocalcemia may prolong symptoms. It is important to monitor both Ca+2 and Mg+2 levels following thyroidectomy to facilitate prompt resolution of symptoms. The aim: is to highlight the prevalence of hypomagnesemia following thyroidectomy and its association with hypocalcemia which mandate early recognition and treatment to prevent prolongation of hypocalcemia and permanent hypoparathyroidism.
Methods: Institutional review board was obtained (E20-4615) and posted in ClinicalTrials.gov NCT04351451. Informed consent taken from all patients. This is a prospective open Label observational pilot study in patients who underwent thyroidectomy. The study period was from January 2019 to January 2020. A total of 74 patients with normal renal function. Serum Ca+2, magnesium, phosphate level, and Vitamin D level are all checked preoperatively and in the first postoperative day.
Results: Post thyroidectomy 56.8% of patients had hypomagnesemia. 59.5.1% had hypocalcemia and 41.9% of had combined low level of Ca+2 and Mg+2 (P = 0.004).
Conclusions: Causes of hypocalcemia and hypomagnesemia following thyroidectomy is of multi factorial related mainly to Ca+2, Mg+2 interaction in relation to PTH level.
Keywords: Hypocalcemia, hypomagnesemia, thyroidectomy
|How to cite this article:|
Abdulkareem AA. Hypomagnesemia following thyroidectomy: Prospective observational - Pilot study. Saudi J Laparosc 2021;6:23-6
| Introduction|| |
Adult body contains approximately 25 g magnesium most of it is intracellular or in the bone Less than 1% of magnesium is in the blood serum. Magnesium plays a role in the active transport of Ca+2 and potassium ions across cell membranes a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm. Normal serum magnesium range between 0.75 and 0.95 (mmol/L). Hypomagnesemia is defined as serum magnesium level <0.75 mmol/L. Ca+2 also is very essential in muscle contraction, building bone, clotting, and nerve impulse transmission and regulating heartbeat. Hypocalcemia is a common biochemical abnormality that can range from asymptomatic to acute life-threatening condition. Hypocalcemia is corrected total serum calcium <2.12 mmol/L. Hypoparathyroidism secondary to damage to the gland or their vascular supply leads to acute hypocalcemia which can result in sever symptom most commonly include paresthesia, muscle spasm, cramps, tetany, and seizures., Magnesium is the second-most abundant intracellular cation of human body. Although a frequent electrolyte abnormality hypomagnesemia is one the most undiagnosed one. Hypomagnesemia can leads to hypocalcemia by suppressing the PTH secretion. Magnesium is the second-most important intracellular cation after potassium. It is an essential regulator of Ca+2 flux and intracellular action of Ca+2. Hypomagnesemia impairs hypocalcemia-induced PTH release, which is corrected rapidly after magnesium replacement. Coexistence of electrolytes abnormalities contributes to the clinical features of hypomagnesemia, the absorption of Ca+2 and magnesium is interdependent and concomitant deficiencies of both is well described. Preoperative preventive magnesium supplements could even raise the risk of postoperative hypocalcemia. However, immediate post thyroidectomy correction of hypomagnesemia improves significantly hypocalcemia.
| Methods|| |
A prospective open-label observational study all patients admitted for thyroidectomy from January 1, 2019, to January 1, 2020were included.
Preoperative serum calcium, magnesium, phosphate, and Vitamin D level all documented. Postoperatively, corrected serum calcium, magnesium, and phosphate level are checked. Serum calcium <2.12 mmol/l is corrected with oral or intravenous calcium infusion plus Vitamin D depending on the severity of symptoms. Serum magnesium <0.75 mmol/l is corrected with titrated infusion of magnesium sulfate.
Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 23.0 software (SPSS Inc., Chicago, IL, USA). If normal distributed, continuous variable was presented as mean (standard deviation [SD]). Student's t-test for paired observation was used for statistical. Pearson Chi-square test was used to compare the percentage for categorical variables. P < 0.05 indicates statistically significant difference.
| Results|| |
A total number of patients were 74 patients (6 male vs. 68 female). The youngest being 12 years and the oldest 87 years with mean 43 (13.86) years. The age was statistically insignificant in relation to post thyroidectomy hypomagnesemia (P = 0.830).
Forty-two (56.8%) patients developed hypomagnesemia post thyroidectomy [Figure 1].
Five (83.3%) of them were male patients while 37 (54.4%) were female. Statistical difference was insignificant in the development of hypomagnesemia between both genders (P = 0.175).
Forty-nine patients had benign pathology 28 (57.1%) of them developed hypomagnesemia. while 25 patients had malignant pathology 14 (56.0%) of them developed hypomagnesemia, (P = 0.925) [Table 1].
|Table 1: Demographic of the study population with post thyroidectomy hypomagnesemia|
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The most common benign pathology was multinodular goiter in 26 patients while papillary thyroid carcinoma was the most common malignancy in 20 patients. The rest of pathology are given in [Table 2], 44 (59.5%) patients had hypocalcemia post thyroidectomy 31 of them developed hypomagnesemia with mean Ca+2 and Mg+2levels of 2.217 (SD-0.526) and 0.7165 (SD-0.079), respectively [Figure 2].
The association of hypomagnesemia and hypocalcemia following thyroidectomy is statically significant with P = 0.004.
The study did not show any association between pre- and post-thyroidectomy Mg+2 level.
| Discussion|| |
The aim of this study is to investigate hypomagnesemia post thyroidectomy in relation to variable thyroid pathology and to highlight the prevalence of hypomagnesemia following thyroidectomy and its association with hypocalcemia which mandate early recognition and treatment to prevent prolongation of hypocalcemia and permanent hypoparathyroidism
In our study, hypocalcemia was higher compared to other studies. However, hypomagnesemia (56.8%) was comparable. 41.9% of patients had low both Ca+2 and Mg+2 (P = 0.004) [Figure 3].
The relation of calcium and magnesium metabolism is complex and mainly related to the interaction of these cations with parathyroid hormone (PTH).
Hypoparathyroidism can reach up to 28.8% leading to transient hypocalcemia in 27.9% of the patients. The prevalence of postoperative hypomagnesemia is about 10%–72%. The relation of calcium and magnesium metabolism is complex and mainly related to the interaction of these cations with PTH. In this study, 59.5% had hypocalcemia which is attributed to low Vitamin D level. Hypomagnesemia was due to redistribution from extracellular fluid to the cell or the bone in hungry bone after parathyroidectomy. Transient hypocalcemia and hypomagnesemia occur frequently after total thyroidectomy the etiology is multifactorial patients are more likely to be symptomatic when both cations are low attempting to correct only hypocalcemia may prolong symptoms. It is important to monitor both Ca+2 and Mg+2 level after total thyroidectomy and correct the deficiencies to facilitate prompt resolution of symptoms. Magnesium also plays a role in the active transport of calcium and potassium ion across cell membranes. Postoperative hypomagnesemia was independent risk factor of biochemical hypocalcemia relative decline of PTH was predominating in predicting symptomatic hypocalcemia. Magnesium could affect calcium level through modulating PTH secretion and PTH receptor sensitivity as well calcium excretion in the kidney. Hypomagnesemia is significantly associated with early hypocalcemia and permanent hypoparathyroidism after thyroidectomy. For that magnesium level should be closely monitored in patients with post thyroidectomy hypocalcemia. Blood serum magnesium concentration is the predominant test used by medicine to assess magnesium status in patients. Magnesium is an essential cofactor of more than 300 enzymes. It acts as a calcium channel antagonist and plays a key role in the modulation of any activity involving calcium.
The limitation of this study is the small sample size.
| Conclusions|| |
Hypomagnesemia following thyroidectomy is common. Hypomagnesemia resulted from low PTH, low calcium level. It worsens hypocalcemia if not treated immediately postoperatively.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
I would like to thank Prof. Eldawlatly and Prof. Aldohayan for their guidance and wise advises as well as to their endless support for me to do this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]