Background: Female gender, particularly of a young age, has been reported as a risk factor for hypocalcemia after total thyroidectomy. There are no studies, however, addressing specifically the influence of women's age and menstrual status on postoperative parathyroid function.
Methods: Cohort study of consecutive patients undergoing total thyroidectomy for benign goiter between 2000-2017, excluding those with associated hyperparathyroidism, reoperation or conservative procedures. Prevalence of postoperative hypocalcemia (s-Ca <8 mg/dL at 24 hours), protracted (1-month) and permanent hypoparathyroidism (>1 year) were the main variables studied. Complete >1-year follow-up was achieved for all patients developing post-thyroidectomy hypocalcemia. Demographic, disease-related, number of parathyroid glands remaining in situ (PGRIS), biochemical and surgical variables were recorded. The impact of menstrual status on parathyroid function was analyzed by comparing two groups of women using a cut-off age of 45 years.
Results: A total of 811 patients were included: 14 percent were males and 86 percent females with a mean age of 53.2 years. The prevalence of postoperative hypocalcemia was ten points higher in women than in men (23.7% vs. 36.4%; P=0.008). Permanent hypoparathyroidism was more common in women than in men (5% vs. 0.9%; P=0.048). Compared to females ≥45 years, young women presented higher rates of all three parathyroid failure syndromes despite similar PGRIS scores. Age <45 years and low PGRIS scores were the only independent variables predicting postoperative hypocalcemia in females.
Conclusions: Premenopausal patients presented a higher prevalence of parathyroid failure and permanent hypoparathyroidism with similar PGRIS scores suggesting the presence of a sex-hormone factor influencing post-thyroidectomy parathyroid function.
Keywords: Hypocalcemia; hypoparathyroidism; menopause; parathyroid glands remaining in situ (PGRIS); prevalence; women.
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