Endocrine Abstracts

Aim: Illustrating a case series of two patients with levothyroxine malabsorption and suboptimal control of the thyroid profile who experienced a significant improvement after switching to liquid levothyroxine.

Material and Methods: Case saries of two patients who were attended in monographic thyroid pathology consultations at Virgen Macarena University Hospital.

Results: Case 1: a 46-year-old female patient who had multinodular goitre detected incidentally by CT. Her personal history included Crohn’s disease, ileocecectomy in 2007. No treatment. A thyroid ultrasound was performed, showing TIRADS4 nodule, on which FNA was performed with suspected papillary carcinoma. A total thyroidectomy was performed. Postoperative control showed Thyrotropin (TSH) levels 39.30 IU/ml and free-thyroxine(FT4) levels 0.75 ng/dl. Non-specific symptoms were reported. The patient required multiple dose readjustments with difficulty in achieving optimal control, requiring up to 300 mg/day of levothyroxine, with level variations, compatible with both treatment deficit and iatrogenic hyperthyroidism. A change to liquid levothyroxine was proposed. the next follow-up visit the laboratory tests showed a thyroid profile within target range: TSH 1.46 IU/ml; FT4 1.32 ng/dl; FT3 2.44pg/ml, dose of 200 mg/day. Case2: a 32-year-old primigravida patient who was unable to adjust her thyroid replacement levels despite progressive increases in the dose of oral levothyroxine. Her personal history included a total thyroidectomy for a papillary thyroid carcinoma that showed excellent control for 10 years with oral levothyroxine 200 mg/day. She reported symptoms of nausea and vomiting from the fourth week of gestation, which had worsened the last few days, leading to a weight loss of 2 kg. She reported muscle fatigue and generalised weakness in the last month. Laboratory tests were normal. Foetal follow-up and obstetric check-ups presented within normal limits. The thyroid profile showed TSH 58 IU/ml; FT4 0.36 ng/dl. A loss of muscle strength of 4/5 was observed on physical examination. Stretch reflexes slightly elongated. No thyroid remnants on cervical ultrasound. Based on these findings and the thyroid hormone levels, a clinical assessment of hypothyroidism secondary to thyroid hormone malabsorption was made, replacing levothyroxine tablets by liquid thyroxine at a dose of 2.3 mg/kg/24h, with thyroid hormone levels returning to normal and fatigue and muscle weakness also subsiding.

Conclusions: There are a significant number of patients who do not achieve an adequate response to oral levothyroxine therapy due to problems in its absorption, with negative consequences on the patient’s well-being. Liquid levothyroxine could help this group of patients achieve more stable TSH values, improving their quality of life and reducing the risk of iatrogenic hyperthyroidism.