Cancer Management and Research (Sep 2019)

Magnesemia: an independent risk factor of hypocalcemia after thyroidectomy

  • Wang W,
  • Meng C,
  • Ouyang Q,
  • Xie J,
  • Li X

Journal volume & issue
Vol. Volume 11
pp. 8135 – 8144

Abstract

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Wenlong Wang*, Chaoyang Meng*, Qianhui Ouyang, Jing Xie, Xinying Li Division of Thyroid, General Surgery Department, Xiangya Hospital, Central South University, Changsha 410008, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xinying LiDivision of Thyroid, General Surgery Department, Xiangya Hospital, Central South University, No.87 Xiangya Road, Changsha 410008, People’s Republic of ChinaTel +86 07 318 975 3710Email [email protected]: 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.Keywords: hypocalcemia, hypomagnesemia, thyroidectomy, magnesium, calcium

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