Endocrine Abstracts

Introduction: Familial neurohypophysial diabetes insipidus (FNDI), an autosomal dominant disorder, comes in many forms that are differentiated by the inheritance pattern and the underlying genetic lesion. The disease is caused by mutations in the vasopressin-neurophysin 2-copeptin protein (AVP-NPII), in wolframin (WFS1) or in proprotein convertase subtilisin/kexin type 1 (PCSK1) genes.

Materials and methods: In this study, we report a case of familial neurohypophyseal DI in three generations; followed in unit of the endocrinology, diabetology, metabolic diseases and nutrition department of the Mohammed VI University Hospital of Marrakesh.

Results: This was a 45-year-old patient who had been suffering from polyuro-polydipsia syndrome since the age of 12, with daily urine volumes ranging from 8.0 to 15.0 l, but had not seen a doctor. The patient was born without complications and had normal puberty. In the family history, three other members of the patient’s family have also had polypolypolydispic syndrome since adolescence, covering three generations, including the patient’s mother, her younger sister and daughter. A water restriction test was performed but the patient did not tolerate it. We completed with the minirin test with a good clinical response: urine concentrated with a volume of 500 ml, and urinary osmolarity at H4 of 276.13 (Fig. 2). As presented in (Fig. 3), cranial MRI revealed a hypersignal region in the posterior pituitary lobe. Serum cortisol, thyroid function, and estrogen were all in the normal range The growth hormone (GH), insulin-like growth factor (IGF)-1 levels and the genetic testing were not performed due to limited financial resources. After treatment with oral desmopressin 60 μg two times daily was started, the symptoms of polydipsia and polyuria were satisfactorily controlled. She currently drinks about 1.5 l of water per day and she has a urine volume of 1.5 l per day. Her sister’s daily water/diuresis intake is 3.0 l/2.0 l, due to the effects of the medication.

Discussion: The mutations involved in familial neurophyphyseal DI include small deletions, as well as missense and nonsense mutations that affect the signal peptide, the AVP moiety, or the AVP carrier protein, NPII.

Conclusion: Familial neurohypophyseal ID is a rare hereditary disease that has a negative impact on the patient’s quality of life. The majority of cases are inherited in an autosomal dominant pattern, which is why screening and appropriate management are necessary.