Endocrine Abstracts

Background: Hypothyroidism is a common disorder, with a prevalence of approximately 5% and incidence of approximately 250/100,000 per year in the adult population, but both prevalence and incidence keep raising. Refractory hypothyroidism is defined by persistent TSH increase despite the administration of supra physiological weight-based dose of levothyroxine, which is usually >1.9ug/kg/d in patients with primary hypothyroidism.

Aim of the Work: To compare the efficacy of the sublingual levothyroxine Na tablets administration with respect to oral levothyroxine tablet in hypothyroid patients refractory to treatment.

Patients and Methods: This was a cross over clinical trial of 6 weeks duration that was conducted at 6th October and Ain Shams university hospitals on 40 subjects who were diagnosed 1ry hypothyroidism and who are documented to be refractory to treatment Thyroxine level was assessed using (Thyroxine absorption test) during standard oral Levothyroxine administration and 1 week after shifting to sublingual route Patients were shifted to the sublingual route on the same dose used with oral route administration Antiparietal cell antibodies, anti-TGA were measured. TSH and free T4 value were assessed finally after 6 weeks of sublingual route administration.

Results: Our study revealed highly statistically significant decrease in TSH level with Sublingual levothyroxine Na tablets (Eltroxin) compared to Oral levothyroxine tablets (Eltroxin) and also statistically significant increase in FT4 with Sublingual levothyroxine Na tablets after 1week compared to Oral levothyroxine tablets, while after 6 WEEKS sublingual levothyroxine Na tablets insignificant compared oral levothyroxine.

Conclusion: Our study revealed that sublingual levothyroxine Na tablet may be more effective than oral levothyroxine tablets in controlling TSH levels in refractory hypothyroidism and sublingual levothyroxine Na tablets may overcome some absorption problems of oral levothyroxine tablets. Autoimmune gastritis should be taken into consideration as an additional factor influencing the daily requirement of levothyroxine Na.