Guía clínica de diagnóstico y tratamiento de las hipofisitis

Use of copeptin in interpretation of the water deprivation test

INTRODUCTION

Currently, the water deprivation test remains the standard method for distinguishing primary polydipsia (PP) from cranial diabetes insipidus (cDI) and nephrogenic diabetes insipidus (nDI). There is increasing interest in a direct estimate of antidiuretic hormone using plasma copeptin as a stable and reliable surrogate marker. We present our experience of measuring copeptin during the water deprivation test.

METHODS

Forty-seven people (17 men) underwent a standard water deprivation test between 2013 and 2021. Plasma copeptin was measured at the start of the test and at the end of the period of water deprivation (maximum osmotic stimulation). Results were classified using prespecified diagnostic criteria. As it is known that a significant proportion of tests will reveal indeterminate results, a final diagnosis was obtained by including relevant pre- and post-test clinical criteria. This diagnosis was then used to plan individual treatment.

RESULTS

Basal and stimulated copeptin were significantly higher in the nephrogenic DI group than other categories (p < .001). There was no significant difference in basal or stimulated copeptin between PP, cDI or partial DI. Nine results were indeterminate where the serum and urine osmolality did not give a unified diagnosis. Stimulated copeptin was helpful in reclassifying these patients into the final diagnostic groups.

CONCLUSION

Plasma copeptin has additional clinical utility in interpretation of the water deprivation test and may continue to have a place alongside newer stimulation tests.

Lymphocytic infundibulo-neurohypophysitis: a clinical overview

Lymphocytic infundibulo-neurohypophysitis is an uncommon inflammatory disorder postulated to be autoimmune in origin. Because of the location of inflammation, it selectively affects the posterior lobe of the pituitary (neurohypophysis) and pituitary stalk (infundibulum). The most common presentation is central diabetes insipidus. Although the definitive diagnosis is established histologically by a pituitary biopsy, radiological imaging can be valuable in diagnosing this condition. In this paper, we provide an overview of the pathophysiology, investigations, management, and outcomes of lymphocytic infundibulo-neurohypophysitis.

[Behçet disease with isolated ACTH deficiency]

We report a case of a patient with longstanding Behçet disease, with neurological symptoms predominantly, who became hospitalized for adrenal insufficiency, caused by isolated deficiency of corticotropin (DAACTH). DAACTH is a typical characteristic of hypophysitis, reported in association with many autoimmune diseases. Nevertheless, hypothalamic-pituitary injury in Behçet disease is exceptional. We review the literature and possible mechanisms of this association until now not reported.

[Antipituitary antibodies in patients with suspected autoimmune hypophysitis]

INTRODUCTION

Definitive diagnosis of autoimmune hypophysitis (AH) is histological. However, a presumptive diagnosis can be made through clinical, biochemical and imaging data.

OBJECTIVE

The objective of this study was to review the presence of antipituitary antibodies (APA) and antithyroid antibodies (ATA) in patients with suspected AH in order to determinate the utility of APA in the diagnosis of AH.

MATERIAL AND METHODS

We studied 36 patients divided into seven groups according to the data suggesting AH (isolated corticotropin deficiency, other idiopathic pituitary deficiencies, idiopathic hyperprolactinemia, empty sella, sellar mass with thickened stalk, proven histological hypophysitis) or because of previous autoimmune endocrine diseases. Twenty-four controls without endocrinological disease were also included. In all subjects, APA were determined by immunofluorescence over primate pituitary gland and ATA by an agglutination technique.

RESULTS

None of the controls and only 9 patients, all of them women, were APA-positive. Of the 9 APA-positive patients, 43% belonged to the group of patients with isolated ACTH deficiency. In 8 patients, APA were determined again during the follow-up; 6 remained APA-negative, but one patient became APA-positive and another became APA-negative. ATA were positive in 12 patients, 22.2% of whom were also APA-positive, and in one control.

CONCLUSIONS

The prevalence of APA positivity among the study patients was low. These antibodies were found only in women, mostly with isolated corticotropin deficiency. APA and ATA coexisted in only 22% of the patients studied.