Severe hypothyroidism in patients dependent on prolonged thyroxine infusion through a jejunostomy

Background and aims: Enteral absorption of thyroxine (T4) is variable; the duodenum and jejunum appear to be the most important sites of absorption. Our objective is to demonstrate that T4 infused via a standard jejunostomy may occasionally be poorly absorbed. Methods: Two patients underwent esophagolaryngeal resection for carcinoma of the cervical esophagus. The procedure was accompanied by complete removal of the thyroid and parathyroid glands. A neck fistula at the gastropharyngeal anastomosis led to a restriction of oral intake; daily requirements of T4 and nutrients were given via the jejunostomy. T4 plasma levels deteriorated and thyroid-stimulating hormone (TSH) levels increased and in the third postoperative week, T4 (300 μg) was administered via a nasogastric tube. Results: Although given a high dose (300 μg) of T4, both patients developed severe hypothyroidism. Infusion of T4 through the nasogastric tube precipitated the normalization of T4 and TSH plasma levels. Both patients (cases 1 and 2) resumed oral intake during the fifth and sixth postoperative weeks respectively. Conclusion: T4 malabsorption may occur in patients dependent on prolonged T4 infusion via a standard jejunostomy.