Endocrine Abstracts

Introduction: Sarcoidosis affects both the central and peripheral nervous system in 5–16% of patients. In most cases, such involvement occurs within a multi-systemic disease. Endocrine manifestations of neurosarcoidosis can be expressed by hypothalamic dysfunction, diabetes insipidus, hypopituitarism, hyperprolactinemia, in isolated fashion or variedly combined.

Herein, we report a case of neurosarcoidosis revealed by an obstructive hydrocephalus, a syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and a secondary amenorrhea in a 34-year-old woman.

Observation: A 34-year-old woman was referred to our department of endocrinology for secondary amenorrheafor the last two years. Her past medical history included an acute obstructive hydrocephalus treated with ventricular drainage and a severe hyponatremia secondary to a SIADH. She reported a weight gain, walking disorders and memory troubles. On physical examination, she had a body weight of 130 kg, a body mass index of 42 kg/m² and a blood pressure of 120/70 mmHg. On biological investigations she had a fasting blood glucose of 0.84 g/l, a natremia of 128 mmol/l, a kaliemia of 4.4 mmol/l, a serum osmotic pressure of 254  mOsm/l, a calcemia of 93 mg/l, an urine osmolality of 565 mOsm/kg and an urinary sodium level of 206  mmol/l. On hormonal investigations, she had a TSH of 1.7 mUI/l, a FT4 of 0.97 ng/dl, a morning cortisol of 16.6 µg/dl, a prolactin of 7 µg/l, a FSH of 1.3 IU/l, a LH of 0.45 IU/l and an estradiol of 13 ng/l. The diagnosis of hypogonadotropic hypogonadism was made. The bone densitometry revealed osteoporosis. The cerebro-medullary magnetic resonance imaging showed a micronodular enhancement of the acqueduct, the fornix columns with extension to the 3rd ventricle, the infundibulum, the pituitary stalk and the optic chiasm, as well as the right temporal and right cerebral peduncle associated with micronodular enhancement of the meninges, the base cisterns and perimedullary. The diagnosis of neurosarcoidosis was established. The patient was put on normal sodium diet, water restriction, bisphosphonates and estroprogestative replacement therapy. Then, she was referred to the department of internal medicine.

Discussion and conclusion: Hypothalamo-pituitary involvement by sarcoidosis is a rare condition. Its most frequent disorders are diabetes insipidus and hyperprolactinemia. Recent studies have demonstrated that gonadotropin deficiency was the most frequent manifestation of the disease as in our case. However, the SIADH is not common in neurosarcoidosis. It could be induced by the hydrocephalus. As hyponatremia persisted after ventricular drainage, SIADH might be caused by neurosarcoidosis.