Thyroid surgery in obese patients: A review of the literature

Transient Hypocalcemia After Total Thyroidectomy: The Obesity Paradox at Work?

INTRODUCTION

With increasing rates of obesity worldwide, a correlation between high body mass index (BMI) and postoperative morbidity after thyroid surgery remains unclear. Postoperative transient hypocalcemia is common after total thyroidectomy due to interruption of parathyroid function. This study examines the relationship between BMI and hypocalcemia after total thyroidectomy.

MATERIALS AND METHODS

A retrospective review of prospectively collected data for 1135 patients who underwent total thyroidectomy for cancer, multinodular goiter (MNG), or Graves' disease between June 2009 and November 2020 at a single institution was performed. BMI groups followed the World Health Organization classification. Hypocalcemia was defined as serum calcium ≤8 mg/dL. Calcium levels measured on postoperative day 0 and the following morning were compared between the BMI groups.

RESULTS

Of 1135 total thyroidectomy patients, 85% were women. The mean age and standard deviation of patients was 49 (± 13) y, with most of Hispanic origin (64%). Overall, 41.5% of patients had cancer, 45% nontoxic MNG, 5.8% toxic MNG, and 12% Graves' disease. Stratified by BMI, 27% of patients were normal, 34% overweight, and 39% obese. Overall, overweight and obese patients experienced less transient hypocalcemia at both time points compared to normal patients postoperatively (P = 0.01 and P = 0.009). Furthermore, overweight and obese patients with Graves' disease experienced less transient hypocalcemia at both time points (P = 0.04 and P = 0.05). There was no statistical difference in other groups.

CONCLUSIONS

A protective role of higher BMI or "obesity paradox" for postoperative hypocalcemia may exist in those obese patients after total thyroidectomy.

Impact of Permanent Post-thyroidectomy Hypoparathyroidism on Self-evaluation of Quality of Life and Voice: Results from the National QoL-hypopara Study

OBJECTIVE

To compare the quality of life (mental health) and voice in patients with or without permanent hypoparathyroidism after total thyroidectomy.

SUMMARY BACKGROUND DATA

Permanent hypoparathyroidism is an underestimated complication of thyroid surgery owing to suppression of parathormone secretion. Few studies have evaluated the consequences of hypoparathyroidism on quality of life and none has studied its effects on voice.

METHODS

The QoL-hypopara study (ClinicalTrial.gov NCT04053647) was a national observational study. Adult thyroidectomized patients were included between January and June 2020. A Serum parathormone level <15pg/mL more than 6 months after surgery defined permanent hypoparathyroidism. Patients answered the MOS-36-item short-form health (SF-36), the Voice Handicap Index (VHI) surveys, and a list of questions regarding their symptoms.

RESULTS

141 patients were included, 45 with permanent hypoparathyroidism. The median period between thyroid surgery and the questionnaire was 6 [Q1-Q3 4-11] and 4 [4-5] years in hypoparathyroid patients and controls respectively. Hypoparathyroid patients presented a reduced median mental score ratio (SF-36) (0.88 [Q1-Q3 0.63-1.01] versus 1.04 [0.82-1.13], P=0.003) and a lower voice quality (incidence rate ratio for total VHI 1.83-fold higher, P<0.001). In multivariable analysis, hypoparathyroidism (-0.17 [95%CI -0.28--0.07], P=0.002), but not age, female sex, thyroid cancer, or abnormal TSH level, was associated with the reduced mental score ratio. Myalgia, joint pain, paresthesia, tetany, anxiety attack and exhaustion were the most common symptoms among hypoparathyroid patients (>50%).

CONCLUSIONS

Hypoparathyroid patients present significantly impaired quality of life, lower voice quality and frequent symptoms. These results reinforce the importance of preventing this complication.