Evolution of blood magnesium and phosphorus ion levels following thyroidectomy and correlation with total calcium values
Keywords:
Magnesium, Phosphorus, Calcium, Thyroidectomy, ComplicationsAbstract
CONTEXT AND OBJECTIVE: Magnesium ion concentration is directly related and phosphorus ion concentration is inversely related to calcemia. The aim of this study was to evaluate the evolution of magnesium and phosphorus ion levels in patients undergoing thyroidectomy and correlate these with changes to calcium concentration. DESIGN AND SETTING: Prospective study at the Alpha Institute of Gastroenterology, Hospital das Clínicas, Universidade Federal de Minas Gerais. METHODS: The study included 333 patients, of both genders and mean age 45 ± 15 years, who underwent thyroidectomy between 2000 and 2005. Total calcium, phosphorus and magnesium were measured in the blood preoperatively and 24 and 48 hours postoperatively. Ionic changes were evaluated according to the presence or absence of postoperative hypocalcemia. RESULTS: There were statistically significant drops in blood phosphorus levels 24 and 48 hours after thyroidectomy, compared with preoperative values, in the patients without hypocalcemia. In the patients who developed hypocalcemia, there was a significant drop in plasma phosphorus on the first postoperative day and an increase (also statistically significant) on the second day, in relation to preoperative phosphorus levels. A significant drop in postoperative magnesium was also observed on the first and second days after thyroidectomy in the patients with hypocalcemia, in relation to preoperative levels. In the patients without hypocalcemia, the drop in magnesium was significant on the first day, but there was no difference on the second day. CONCLUSION: Despite the postoperative changes, neither magnesium nor phosphorus ion levels had any role in post-thyroidectomy calcemia.
Downloads
References
Arioli EL. Hipocalcemia [Hypocalcemia]. Arq Bras Endocrinol Metab. 1999;43(6):467-71.
Falk SA, Birken EA, Baran DT. Temporary postthyroidectomy hypocalcemia. Arch Otolaryngol Head Neck Surg. 1988;114(2):168-74.
Lemaire FX, Debruyne F, Delaere P, Vander Poorten V. Parathyroid function in the early posto- perative period after thyroidectomy. Acta Otorhinolaryngol Belg. 2001;55(2):187-98.
Salles JMP, Soares JMA, Sousa AA, Salles PV. Prevenção e tratamento das complicações da tireoidectomia. In: Carvalho MB, editor. Tratado de tireóide e paratireóide. Rio de Janeiro: Rubio; 2007. p. 651-62.
International Ethical Guidelines for Biomedical Research Involving Human Subjects. Gene- va: Council for International Organizations of Medical Sciences (CIOMS) in collaboration with the World Health Organization (WHO); 2002. Available from: http://www.fhi.org/trai-ning/fr/retc/pdf_files/cioms.pdf. Accessed in 2010 (Sep 16).
Schaefer SD, Fee WE Jr. Thyroid surgery: surgical and metabolic causes of hypocalcemia. Arch Otolaryngol. 1978;104(5):263-6.
Fahmy FF, Gillett D, Lolen Y, Shotton JC. Management of serum calcium levels in post-thyroi- dectomy patients. Clin Otolaryngol Allied Sci. 2004;29(6):735-9.
Freitag JJ, Martin KJ, Conrades MB, et al. Evidence for skeletal resistance to parathyroid hormone in magnesium deficiency. Studies in isolated perfused bone. J Clin Invest. 1979;64(5):1238-44.
Mori S, Harada S, Okazaki R, et al. Hypomagnesemia with increased metabolism of pa- rathyroid hormone and reduced responsiveness to calcitropic hormones. Intern Med. 1992;31(6):820-4.
Wilson RB, Erskine C, Crowe PJ. Hypomagnesemia and hypocalcemia after thyroidectomy: prospective study. World J Surg. 2000;24(6):722-6.
