ABSTRACT Objective: The conversion of Hashimoto's thyroiditis (HT) to hyperthyroidism due to thyrotropin receptor antibodies is intriguing and considered rare. The contribution of TSH receptor blocking antibodies (TRAb), which may be stimulators (TSAb) or blockers (TBAb), is suspected. We describe clinical and biological variables in a series of patients switching from Hashimoto's thyroiditis to Grave's disease. Subjects and methods: Retrospective case study of 24 patients with Hashimoto's thyroiditis followed during 48 ± 36 months that developed later Graves’ disease (GD). These variables were analysed in the hypo and hyperthyroid phase: age, sex, initial TSH, free triiodothyronine (fT3), free thyroxine (fT4), anti-TPO, TBII antibodies, parietal cell autoantibodies, time between hypo and hyperthyroidism, thyroid volume and levothyroxine doses (LT). Results: In HT, mean TSH was 9.4 ± 26.1 UI/L and levothyroxine treatment was 66.2 ± 30.8 µg/day. The switch to GD was observed 38 ± 45 months after HT diagnosis. As expected, we found significant differences on TSH, FT3, FT4 and TBAb levels. Three out of 14 patients had parietal cell autoantibodies. In two of these three cases there was an Helicobacter pylori infection. There were no significant differences between HT and GD groups with respect to thyroid volume. Conclusions: To our knowledge, large series documenting the conversion of HT to GD are scarce. Although rare, this phenomenon should not be misdiagnosed. Suspicion should be raised whenever thyroxine posology must be tapered down during the follow-up of HT patients. Further immunological and genetic studies are needed to explain this unusual autoimmune change.

SUMMARY Neuroendocrine tumors (NETs) can secrete hormones, including ectopic secretions, but they have been rarely associated with malignant hypercalcemia. A 52-year-old man with a history of diabetes mellitus was diagnosed with a pancreatic tumor. A pancreatic biopsy confirmed a well-differentiated pancreatic NET (pNET). The patient subsequently developed liver metastasis and hypercalcemia with high 1,25 OH vitamin D and suppressed parathyroid hormone (PTH) levels. Hypercalcemia was refractory to chemotherapy, intravenous saline fluids, diuretics, calcitonin and zoledronate. Cinacalcet administration (120 mg/day) resulted in a significant calcium reduction. Hypocalcemia was observed when sunitinib was added three months later and cinacalcet was stopped. Subsequently, the calcium and PTH levels normalized. After six months, we observed 20% shrinkage of the pancreatic tumor and necrosis of a liver metastasis. Cinacalcet is an allosteric activator of the calcium receptor agonist, and it is used for severe hypercalcemia in patients with primary (benign and malignant) hyperparathyroidism. In this patient, cinacalcet demonstrated a calcium lowering effect, normalized hypophosphatemia, and improved the clinical condition of the patient. The mechanism through which cinacalcet improved PTH-rp mediated hypercalcemia is still unclear, but studies have suggested that a potential mechanism is the activation of calcitonin secretion. Sunitinib is an oral multi-targeted tyrosine kinase inhibitor used to treat advanced pNETs. The hypocalcemic effects of sunitinib have not been previously described in a patient with pNET. Here, we report for the first time the successful combination of cinacalcet and sunitinib in the treatment of a pNET patient presenting with malignant hypercalcemia.

Craniopharyngioma is the most common pituitary tumor in childhood. It can compromise the pubertal development because of its evolution or treatment. Syndrome of Klinefelter is the most common cause of hipergonadotrophic hypogonadism in males. The concomitant presentation of both entities is extremely low (1/10(9)) and the pathophysiological association is questionned. We present the case of a 18-year-old Belgian patient. He had a diagnosis of craniopharyngioma in childhood and he presented with panhypopituitarism after radiotherapy and surgical treatment. At the age of 14, he started pubertal induction with gonadotropin therapy without clinical response. A genetic evaluation confirmed a homogeneous 47, XXY karyotype. Failure of exogenous gonadotropin therapy revealed the hidden association of primary and secondary hypogonadism, demonstrating the importance of the followup and a multidisciplinary approach in these patients.

Los craneofaringiomas son de los tumores hipofisarios más frecuentes en la niñez y, sea por su evolución o por el tratamiento que requieren, pueden comprometer el desarrollo puberal. El síndrome de Klinefelter es la causa más frecuente de hipogonadismo hipergonadotrópico en el varón. La presentación concomitante de ambas entidades es extremadamente baja (1/10(9)) y plantea un interrogante acerca de una probable asociación fisiopatológica. Se presenta el caso de un paciente belga de 18 años, con diagnóstico de craneofaringioma en la niñez y panhipopituitarismo luego del tratamiento quirúrgico y radioterápico. Al llegar a los 14 años, se inició la inducción puberal con gonadotropinas. Ante la falta de respuesta clínica, se completó una evaluación genética, que evidenció, de manera homogénea, una trisomía XXY. La falta de respuesta al tratamiento de inducción con gonadotropina exógena reveló la asociación de hipogonadismo primario y secundario, que demostró la importancia del seguimiento multidisciplinario que estos pacientes requieren.