Switching from the tablet to the powder formulation of levothyroxine corrects severe hypothyroidism in a patient with lactose intolerance.

We describe a case of a 38-year-old woman who, after radioactive iodine therapy for Graves' disease, developed severe hypothyroidism despite receiving a high dose of levothyroxine (L-T4) tablet as replacement therapy. Her thyroid stimulating hormone (TSH) remained to be high despite the dose of L-T4 tablets to 400 µg/day after treatment for hypothyroidism, and the patient complained of general malaise and edema of the legs. Reduced intestinal absorption of L-T4 is the most common cause of failure to achieve the therapeutic target in hypothyroid patients receiving replacement therapy. She was admitted to our hospital for severe hypothyroidism due to resistance to treatment with L-T4 tablet. Our patient was found to have lactose intolerance (LI) by a detailed examination during hospitalization. Therefore, we assumed that LI was impairing intestinal absorption of L-T4 tablet in our patient, leading to severe hypothyroidism. The patient was switched to the powder formulation of L-T4 at the same daily dose, and serum levels of thyroid-stimulating hormone and thyroid hormones normalized. This is the case in which hypothyroidism due to reduced absorption of L-T4 tablet in a patient with LI was resolved by switching to L-T4 powder formulation.

Denosumab improves clinical manifestations of hypophosphatemic osteomalacia by adefovir-induced Fanconi syndrome: a case report.

BACKGROUND: Adefovir dipivoxil is a nucleotide analogue that is approved for treatment of chronic hepatitis B. Adefovir dipivoxil is associated with proximal tubular dysfunction, resulting in Fanconi syndrome, which can cause secondary hypophosphatemic osteomalacia. We describe a case of a patient with hypophosphatemic osteomalacia secondary to Fanconi syndrome induced by adefovir dipivoxil concomitantly with osteoporosis in whom clinical symptoms were improved by adding denosumab (a human monoclonal antibody targeting the receptor activator of nuclear factor-κB ligand) to preceding administration of vitamin D3. CASE PRESENTATION: A 60-year-old Japanese man had been receiving low-dose adefovir dipivoxil (10 mg/day) to treat chronic hepatitis B for approximately 5 years. He presented to an orthopedic surgeon with severe pain of the right hip and no trauma history, and fracture of the neck of the right femur was identified. In addition, 99mTc-hydroxymethylene diphosphate scintigraphy revealed significantly abnormal uptake in the bilateral ribs, hips, and knees, and he was therefore referred to our university hospital for evaluation of multiple pathological fractures. We diagnosed hypophosphatemic osteomalacia due to Fanconi syndrome induced by adefovir dipivoxil therapy. Although we reduced the patient's adefovir dipivoxil dose and added calcitriol (active vitamin D3), he did not respond and continued to complain of bone pain. Several bone resorption markers and bone-specific alkaline phosphatase were also persistently elevated. Therefore, we added denosumab to vitamin D3 supplementation for treatment of excessive bone resorption. Two months after initiation of denosumab, his hip and knee pain was relieved, along with a decrease in serum alkaline phosphatase and some bone resorption markers. CONCLUSIONS: Although denosumab is not generally an appropriate treatment for acquired Fanconi syndrome, it may be useful for patients who have hypophosphatemic osteomalacia due to adefovir dipivoxil-induced Fanconi syndrome associated with excessive bone resorption. However, clinicians should keep in mind that if denosumab is administered to patients with hypophosphatemic osteomalacia accompanied by excessive bone resorption, adequate vitamin D and/or phosphate supplementation should be done before administration of denosumab.

Iodide Transport Defect and Breast Milk Iodine.

BACKGROUND: Iodide transport defect (ITD) is a dyshormonogenetic congenital hypothyroidism caused by sodium/iodide symporter (NIS) gene mutations. In the lactating mammary gland, iodide is concentrated by NIS, and iodine for thyroid hormone synthesis is thereby supplied to the infant in the breast milk. CASE DESCRIPTION: A 34-year-old Japanese woman was diagnosed with ITD caused by a homozygous NIS gene mutation T354P. She had begun treatment of primary hypothyroidism with levothyroxine at the age of 5. She delivered a baby at the age of 36. The iodine concentration in her breast milk was 54 µg/l. She took a 50-mg potassium iodide tablet daily to supply iodine in the breast milk, starting on the 5th day postpartum. Her breast milk iodine concentration increased to 90 µg/l (slightly above the minimum requirement level). The patient weaned her baby and stopped taking the daily potassium iodide tablet 6 weeks postpartum, and the baby began to be fed with relatively iodine-rich formula milk. The baby's thyroid function remained normal from birth until 6 months of age. CONCLUSION: Possible iodine deficiency in the infant breast-fed by an ITD patient should be kept in mind. Prophylactic iodine supplementation is essential for such infants in order to prevent severe iodine deficiency.