Nephrogenic diabetes insipidus as the first manifestation of Ectopic ACTH syndrome in a HIV infected patient

Everlayny Fiorot Costalonga,Weverton Machado Luchi,Thais Leibel Sant’ Anna Santos,Francisca Germanya Morais Borges,Susan Caroline Azevedo Aredes,Veronica Gabriela Guerra,Amanda Weberling Coelho Moreira,Leon Cleres Penido Pinheiro

doi:10.3823/2029

Everlayny Fiorot Costalonga, Weverton Machado Luchi + Show 6 more

Open Access

https://doi.org/10.3823/2029

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Abstract

The Ectopic Adrenocorticotrophic Hormone (ACTH) Syndrome (EAS) is a high mortality paraneoplastic syndrome, which represents 10-15% of Cushing Syndromes (CS). Around 70% of tumors are located in the chest, neck or adrenals. It frequently has atypical manifestations, leading to delay in diagnosis. Here, we report a particular case of EAS manifested predominantly by nephrogenic diabetes insipidus (NDI). A 48 years old man, HIV infected, was admitted with polyuria, polidipsia and lower limb weakness. He had hipertension, crackles in the right hemithorax and linphanedophathy. Laboratory assessments showed hyperglycemia, hypernatremia, severe hypocalemia, metabolic alkalosis and low urinary osmolarity, which persisted after water deprivation test and desmopressin administration, characterizing a NDI. Chest images showed a lung tumor, which, in conjunction with the clinical and laboratorial picture lead to the suspicion of EAS. Cortisol levels after dexametasona were 143μg/dL and serum ACTH was 630pg/mL. Pituitary was normal and adrenals showed bilateral hyperplasia. Lymph node biopsy revealed a neuroendocrine tumor with positive immunohistochemistry for ACTH. Patient died a few days later due to nosocomial pneumonia. The EAS can be associated with very high cortisol levels, which evolves rapidly, resulting in the absence of typical features of CS. The knowledge of the different clinical presentations is essential to establish prompt diagnostic and support. This syndrome has to be considered in patients with a neoplasm and diabetes insipidus, especially if accompanied by signs of excess of mineralocorticoid action. Although the ideal treatment is excision of the tumor, adrenolitic drugs may help to reduce complications and improve survival.

Highlights

The Ectopic Adrenocorticotropic Hormone (ACTH) Syndrome (EAS) is a high mortality paraneoplastic condition characterized by a severe hypercortisolism state induced by ectopic secretion of ACTH
We describe a case of EAS associated to lung cancer in a HIV infected man, in which the initial manifestation was polyuria and polydipsia secondary to Diabetes Insipidus (DI)
We presented a case of EAS in a HIV infected patient, manifested predominantly by nephrogenic diabetes insipidus (NDI), metabolic alkalosis and hypocalemia, which were mistakenly attributed to tenofovir nephrotoxicity and/or hypokalemia at first

Summary

Introduction

The Ectopic Adrenocorticotropic Hormone (ACTH) Syndrome (EAS) is a high mortality paraneoplastic condition characterized by a severe hypercortisolism state induced by ectopic secretion of ACTH. Very few cases of DI have been reported in association with EAS, and most of them were linked to intrasellar metastasis of the primary ACTH – producing tumor [4] In this case, diluted polyuria persisted after vasopressin administration and pituitary image did not show infiltrative lesions, indicating a nephrogenic form of DI, which is a frequently unknown or forgotten manifestation of severe hypercortisolism. The chest CT exhibited a pulmonary right spiculated nodule of 2.2 cm, in the right upper lobe, associated with mediastinal and hilar lymphadenopathy (Figure 1B) In face of this clinical, laboratory and radiological scenario, we hypothesized the possibility of ectopic ACTH secretion. His baseline serum cortisol dosage was 63ug/ml (reference values: 6.2-19.4 ug/ml) and there was no suppression after low-dose dexamethasone test (1 mg overnight: 143μg/dL; 2mg 48h: 63 μg/dL). He was referred to an oncology center with the purpose of specific chemotherapy treatment, but died a few days later due to nosocomial pneumonia

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