日比 八束

We herein report the case of a patient with critical hyperkalemia after unilateral adrenalectomy (ADX) for aldosterone-producing adenomas, which were coexisting with primary hyperparathyroidism. A right adrenal tumor oversecreting mineral corticoid was identified in a 62-year-old female whose kidney function had been impaired due to primary hyperaldosteronism and hyperparathyroidism. The ADX improved her hypertension with normalization of the plasma aldosterone concentration, but without adequately increasing her plasma renin activity. Her eGFR further decreased postoperatively, hyperkalemia appeared and the serum potassium level rose to 6.3 mEq/L at 3 months after ADX. Then, treatment with calcium polystyrene sulfonate jelly was started. Eight months after ADX, a left lower parathyroidectomy was performed, and the serum calcium and intact parathyroid hormone levels decreased to the normal range. The hyperkalemia was difficult to control within 20 months postoperatively without treatment with calcium polystyrene sulfonate jelly or hydrocortisone. This suggests that unmasking the renal impairment and relative hypoaldosteronism after ADX might induce critical hyperkalemia.

We report a rare case with pheochromocytoma as the first manifestation of multiple endocrine neoplasia type 2A with RET mutation S891A. Bilateral pheochromocytomas were identified in a 54-year-old woman. Screening for RET revealed a rare S891A mutation located in the intracellular tyrosine kinase domain. This mutation was previously recognized as one of the mutations only in cases manifesting solely medullary thyroid carcinomas (MTCs). Since calcitonin stimulation test indicated positive result, total thyroidectomy was performed 1 year after the bilateral adrenalectomy, and C-cell hyperplasia was diagnosed by histopathological examination. Our report suggests that cases with S891A mutation, akin to those with other RET mutations, require screening for pheochromocytoma. In addition, it is indicated that calcitonin stimulation test should be performed even in the unaffected elder cases with S891A mutation although the mutation is classified as lowest risk group on MTC in guidelines.

Accumulating evidences suggest RET gene's involvement in development of the kidney in mice and humans. Although it is well known that RET mutation causes multiple endocrine neoplasia type 2A (MEN2A), thus far only 3 individuals have been reported to have MEN2A and renal agenesis/dysgenesis. We report a MEN2A family with RET mutation in which two asymptomatic carriers presented with unilateral renal agenesis. A 48-year-old woman underwent total thyroidectomy with regional lymph node dissection in our department for medullary thyroid carcinoma. She had earlier surgical treatment for a left adrenal pheochromocytoma at the age of 45. In the screening for MEN type 2 for her three sons, a CT scan for adrenal pheochromocytoma incidentally found unilateral renal agenesis in two of the sons, one of whom had suffered from Hirschsprung's disease (HSCR). They had contralateral kidneys exhibiting compensatory hypertrophy and normal renal function. Genetic analysis detected C618R RET mutation in the proband and her 3 sons, and no other mutations were found in RET as well as glial cell line-derived neurotrophic factor (GDNF). Our data lend support to the hypothesis that constitutive active RET mutation in MEN type 2 might partially impair RET function and thereby cause loss of function phenotype such as renal agenesis or HSCR. © The Japan Endocrine Society.

永続的副甲状腺機能低下症は，甲状腺全摘術で懸念すべき合併症の一つである。今回甲状腺全摘を要する疾患ごとに，副甲状腺の機能温存状況を検討した。その結果，術後１年の時点でintact PTH値が正常値下限であった症例の頻度は甲状腺癌症例で0.78％，バセドウ病で2.0％，非中毒性甲状腺腫では０％であった。また副甲状腺が将来過形成をきたす可能性のある重症慢性腎臓病やMEN2A型への甲状腺全摘を施行した症例では副甲状腺を全摘し，一部前腕筋肉内へ自家移植したがこれらの症例で永続的副甲状腺機能低下症をきたしたものはなかった。副甲状腺の温存状況は個々の症例や対象疾患により様々ではあるが，まずは発見しやすい上腺を確実に術中に同定することが重要と思われる。