Pattern of sub-clinical dysthyroidism in a postthyroidectomy cohort: Implications for supplementary treatment

Abstract

Background: Defective thyroid functioning is referred to as dysthyroidism. Despite incomplete thyroidectomy or thyroxine supplementation, post-thyroidectomy patients may still experience dysthyroidism. Many times, this may be sub - clinical. This study aimed to assess the prevalence and pattern of sub-clinical dysthyroidism following thyroid surgery. 

Methods: In this prospective cohort study, 40 patients were consecutively recruited following conventional thyroidectomy and followed up to 12months. All patients were euthyroid at surgery. At 12 months serum TSH, T4 and T3 levels were measured and the patients clinically assessed. The prevalence and pattern of dysthyroidism was analysed statistically against the patient demographics, clinical and peri-operative variables for significance, using stata version 13. The confidence interval was at 95% and the statistical significance at a p-value of <0.05. 

Results: The mean age was 44.3 years (M:F= 1: 12.3). 20% of the patients had medical comorbidities. The types of surgery performed were sub-total thyroidectomy (55%), near total thyroidectomy (25%) and total thyroidectomy (20%). The prevalence of postoperative dysthyroidism was 52.5%. 22.7% of patients who underwent sub-total thyroidectomy had dysthyroidism. Most patients (90%) who were on thyroxine supplement (following total or near total thyroidectomy) still developed dysthyroidism (P= 0.017). The type of resection done had the greatest significance (P= 0.000). Other factors associated with dysthyroidism albeit non-significantly were history of pre-operative hyperthyroidism, middle age (40 - 60 years), and female gender. 

Conclusions: The prevalence of dysthyroidism in this cohort was high which may reflect the broader picture among post - thyroidectomy patients in this setting. Regular biochemical testing in post-thyroidectomy patients is important to identify and correct dysthyroidism early. This requires frequent follow-up and accurate dose adjustment, based on objective assessments like weight or body mass index. 

Keywords: post-thyroidectomy; dysthyroidism; hypothyroidism; hyperthyroidism; sub-clinical dysthyroidism; prospective; cohort