Role of magnesium in post thyroidectomy hypocalcemia.

Anish Jacob, Cherian (2014) Role of magnesium in post thyroidectomy hypocalcemia. Masters thesis, Christian Medical College, Vellore.


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Aim and objectives: The aim of the study was to evaluate the role of magnesium in postthyroidectomy hypocalcemia. The objectives were to: A) Estimate the prevalence of hypomagnesemia in patients undergoing thyroidectomy and in post thyroidectomy patients and its relationship with hypocalcemia B) Evaluate the relationship of the following factors to post thyroidectomy hypocalcemia: Age, gender, vitamin D level, thyrotoxicosis, inadvertent parathyroid injury/removal, hemodilution, extent of dissection and duration of operation Material and methods: This was a prospective observational study conducted from 1st October 2012 to 30th September 2013 at the department of Endocrine Surgery, Christian Medical College, Vellore, India. The sample size was 50. The statistical analysis was performed using STATA I/C 10.1. This study was approved by the institution review board. Results: Majority of the patients (26%) were in the fifth decade. A female predominance was noted. Seventy four percent of the patients had carcinoma thyroid, the most common malignancy being papillary carcinoma thyroid. Seventy two percent underwent total thyroidectomy. The prevalence of hypomagnesemia preoperatively was 24% and following thyroidectomy this increased to 70% percent. Hypovitaminosis D was prevalent (62%). Postoperative hypocalcemia was seen in fifteen patients (30%). We found a similar trend of the fall and gradual normalization of calcium and magnesium postoperatively though there was no significant association between the two. There was a significant direct correlation between amount of fluids used and development of hypocalcemia (p=0.04) and low PTH (<8pg/ml) with postoperative hypocalcemia (p=0.029). There seemed to be a protective effect of hypovitaminosis D for hypocalcemia. Age of the patient, gender, presence of thyrotoxicosis and duration of operation had no bearing on the postoperative hypocalcemia in our study. Conclusions: 1) The prevalence of hypomagnesemia is 24% preoperatively in this cohort of patients. They were all mild deficiency 1.6 to 1.8. Vitamin D deficiency (< 20) was 62%. 2) The postoperative hypocalcemia (calcium <8mg/dl) rate was 30%. Hypovitaminosis D appeared to protect against postoperative hypocalcemia; this finding is at variance with published literature. 3) There was a marked rise in postoperative hypomagnesemia (70%). A similar pattern of fall in calcium and magnesium following thyroid surgery which normalized by one to two weeks without intravenous correction was observed. 4) Hemodilution and low PTH were significantly associated with post thyroidectomy hypocalcemia. The ROC curve showed that a PTH of 4.1-6pg/ml was the best predictor of hypocalcemia. 5) The cause of hypocalcemia post thyroidectomy in this study is mainly a factor of parathyroid function and fluid status. Magnesium levels tend to mimic the calcium levels postoperatively and there is possibly an association rather than a causation. This study therefore does not prove or disprove the role of magnesium supplementation to help correct postoperative hypocalcemia.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Magnesium, hypomagnesemia, hypocalcemia, total thyroidectomy, thyroidectomy complications
Subjects: MEDICAL > Endocrine Surgery
Depositing User: Kambaraman B
Date Deposited: 23 Jun 2017 06:53
Last Modified: 23 Jun 2017 07:30

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