Studies on anti-rabphilin-3A antibodies in 15 consecutive patients presenting with central diabetes insipidus at a single referral center

A Pregnant Woman with Excess Vasopressinase-Induced Diabetes Insipidus Complicated by Central Diabetes Insipidus like Lymphocytic Infundibulo-Neurohypophysitis

Background

Gestational diabetes insipidus (DI) is a very rare complication of pregnancy. We present a case of gestational DI combining two different types of DI. Case Presentation. A 39-year-old pregnant woman suddenly presented with thirst, polydipsia, and polyuria after 31 gestation weeks (GWs). Based on laboratory findings of hypotonic urine (78 mOsm/kgH2O) with higher plasma osmolality (298 mOsm/kgH2O) and higher serum sodium levels (149 mEq/L), gestational DI was suspected, and the clinical course was monitored without therapy until the results of a measurement of plasma arginine vasopressin (AVP) levels were available. However, she subsequently developed acute prerenal failure and underwent an emergency cesarean section at 34 GWs. Her resected placenta weighed 920 g, nearly twice the normal weight. Immediately following delivery, intranasal 1-desamino-8-D-arginine vasopressin was administered, and her symptoms promptly disappeared. Afterward, her predelivery plasma AVP level was found to have been inappropriately low (0.7 pg/mL) given her serum sodium level. The patient's serum vasopressinase level just before delivery was 2,855 ng/mL, more than 1,000 times the upper limit of the normal range, suggesting excess vasopressinase-induced DI. The presence of anti-rabphilin-3A antibodies in the patient's blood, a hypertonic saline infusion test result, and loss of the high-intensity signal of the posterior pituitary on fat-suppressed T1-weighted magnetic resonance images without thickening of the stalk and enlargement of the neurohypophysis suggested concurrent central DI-like lymphocytic infundibulo-neurohypophysitis (LINH).

Conclusion

In addition to the degradation of AVP by excess placental vasopressinase due to the enlarged placenta, an insufficient compensatory increase in AVP secretion from the posterior pituitary gland due to LINH-like pathogenesis might have led to DI symptoms.

Absence of anti-rabphilin-3A antibodies in children and young adults with idiopathic central diabetes insipidus: a potential clue to elucidating a tumor etiology

BACKGROUND

Central diabetes insipidus (CDI) is a rare condition caused by various underlying diseases, including neoplasms, autoimmune diseases, and infiltrative diseases. Differentiating between CDI etiologies is difficult. What has initially been classified as "idiopathic" central diabetes insipidus might in fact underlie various pathogenic mechanisms that are less understood to date and/or are not obvious at initial presentation. Therefore, even if idiopathic CDI is diagnosed at the time of onset, it is common for tumors such as germinoma to develop during surveillance. Crucially, a delayed diagnosis of germinoma may be associated with a worse prognosis. Recently, the presence of anti-rabphilin-3A antibodies has been found to be a highly sensitive and specific marker of lymphocytic infundibuloneurohypophysitis, an autoimmune-mediated CDI.

CASE PRESENTATION

We herein present two cases, namely, a 13-year-old boy (patient 1) and a 19-year-old young man (patient 2) who were diagnosed with idiopathic CDI. In both patients, panhypopituitarism developed. Magnetic resonance imaging revealed pituitary stalk thickening and pituitary swelling approximately 1 1/2 years after the onset of CDI. Western blotting did not reveal the presence of anti-rabphilin-3A antibodies in serum in either patient, suggesting that autoimmune mechanisms might not be involved. Both patients were subsequently diagnosed with germinoma on pathological examination. They received chemotherapy, followed by radiation therapy. Notably, testosterone and insulin-like growth factor-1 levels normalized, and libido and beard growth recovered after chemoradiotherapy in patient 2.

CONCLUSION

Our data suggest that the absence of anti-rabphilin-3A antibodies in young patients clinically diagnosed with idiopathic CDI may increase the probability of the development of non-lymphocytic lesions, including germinoma. We thus recommend a more attentive approach at the onset of these diseases.

Pregnancy-related hypophysitis revisited

OBJECTIVE

The aim of the study is to assess the distinguishing features of pregnancy-related hypophysitis (PR-Hy) compared to non-pregnancy autoimmune hypophysitis and to evaluate the changing therapeutic approaches and outcomes in PR-Hy over time.

DESIGN

Retrospective analysis of all published cases with PR-Hy and 6 own cases.

METHODS

A PubMed search was performed and abstracts screened for publications with information on cases with PR-Hy from which full-text review was performed. Clinical features, diagnostic findings, and outcome in relation to treatment modalities in PR-Hy were assessed.

RESULTS

One hundred and forty-eight cases with PR-Hy were identified. PR-Hy was significantly delimited from non-PR-Hy by the frequent occurrence of the chiasmal syndrome (50% vs 13%, P < .0001), higher rate of intrasellar origin (94% vs 74%, P = .0005), lower rate of pituitary stalk involvement (39% vs 86%, P < .0001), and low rate of diabetes insipidus (12% vs 54%, P < .0001). The role of surgery in PR-Hy decreased over time while noninvasive treatment modalities increased. The recurrence rate after high-dose glucocorticoid therapy (33%) was high and exceeded that of surgery (2%) and conservative management (2%). In contrast to initial reports on PR-Hy, recent literature regarding outcome of mother's and child's health was positive. The frequency of spontaneous preterm delivery was not increased. Recurrent PR-Hy in a subsequent pregnancy was reported in only two females.

CONCLUSION

PR-Hy has distinct features that delineate the disorder from non-PR-Hy. With increasing experience in diagnosis, availability of adequate replacement therapy, and improved treatment modalities, PR-Hy has lost its threat and the outcome is encouraging.

Central diabetes insipidus with anti-rabphilin-3A antibody positivity causing hypovolemic shock after resection of tumorous lesions in the pelvic cavity

A 36-year-old female was pointed out to have liver enzyme elevation by routine health checkup. Subsequent contrast-enhanced CT scan identified gigantic uterine fibroids and retroperitoneal tumor. She was referred to the gynecologist at JA Toride Medical Center and planned to undergo a uterus enucleation and biopsy of the retroperitoneal tumor. The surgery was conducted without any troubles. After the surgery, the patient presented polyuria with urine volume 10-20 L a day and developed hypovolemic shock. Laboratory test revealed hypotonic urine and hypernatremia. Arginine vasopressin (AVP) loading test suggested shortage of endogenous vasopressin. Since the subcutaneous administration of AVP was not sufficient to control the urine volume, continuous intravenous infusion of AVP was initiated. After achieving hemodynamic stability, the treatment was switched to oral desmopressin. MRI finding indicated attenuation of high signal in posterior pituitary in T1 weighted image while neither enlargement of pituitary nor thickening of pituitary stalk was indicated by enhanced MRI. Hypertonic salt solution test indicated no responsive elevation of AVP, confirming the diagnosis of central diabetes insipidus (CDI). Her anterior pituitary function was preserved. Only anti-rabphilin-3A antibody was found positive in the serum of the patient, while other secondary causes for CDI were denied serologically and radiologically. Hence, lymphocytic infundibuloneurohypophysitis　(LINH) was suspected as the final diagnosis. Hormonal replacement therapy by nasal desmopressin was continued and the patient managed to control her urine volume. In cases of CDI considered idiopathic with conventional examinations, anti-rabphilin-3A antibody may be a clue for determining the cause as LINH.