Radionuclide Esophageal Transit Scintigraphy in Primary Hypothyroidism

Esophageal dysmotility is associated with gastrointestinal dysmotility in various systemic and neuroregulatory disorders. Hypothyroidism has been reported to be associated with impaired motor function in esophagus due to accumulation of glycosaminoglycan hyaluronic acid in its soft tissues, leading to changes in various contraction and relaxation parameters of esophagus, particularly in the lower esophageal sphincter. In this study we evaluated esophageal transit times in patients of primary hypothyroidism using the technique of radionuclide esophageal transit scintigraphy.

Thirty-one patients of primary hypothyroidism and 15 euthyroid healthy controls were evaluated for esophageal transit time using 15-20 MBq of Technetium-99m sulfur colloid diluted in 10-15 mL of drinking water. Time activity curve was generated for each study and esophageal transit time was calculated as time taken for clearance of 90% radioactive bolus from the region of interest encompassing the esophagus. Esophageal transit time of more than 10 seconds was considered as prolonged.

Patients of primary hypothyroidism had a significantly increased mean esophageal transit time of 19.35 ± 20.02 seconds in comparison to the mean time of 8.25 ± 1.71 seconds in healthy controls (P < 0.05). Esophageal transit time improved and in some patients even normalized after treatment with thyroxine. A positive correlation (r = 0.39, P < 0.05) albeit weak existed between the serum thyroid stimulating hormone and the observed esophageal transit time.

A significant number of patients with primary hypothyroidism may have subclinical esophageal dysmotility with prolonged esophageal transit time which can be reversible by thyroxine treatment. Prolonged esophageal transit time in primary hypothyroidism may correlate with serum thyroid stimulating hormone levels.