Other Pituitary Conditions and Pregnancy

Adrenal insufficiency in pregnancy: Physiology, diagnosis, management and areas for future research

Adrenal insufficiency requires prompt diagnosis in pregnancy, as untreated, it can lead to serious consequences such as adrenal crisis, intrauterine growth restriction and even foetal demise. Similarities between symptoms of adrenal insufficiency and those of normal pregnancy can complicate diagnosis. Previously diagnosed adrenal insufficiency needs monitoring and, often, adjustment of adrenal hormone replacement. Many physiological changes occur to the hypothalamic-pituitary-adrenal (HPA) axis during pregnancy, often making diagnosis and management of adrenal insufficiency challenging. Pregnancy is a state of sustained physiologic hypercortisolaemia; there are multiple contributing factors including high plasma concentrations of placental derived corticotropin-releasing hormone (CRH), adrenocorticotropin (ACTH) and increased adrenal responsiveness to ACTH. Despite increased circulating concentrations of CRH-binding protein (CRH-BP) and the major cortisol binding protein, corticosteroid binding globulin (CBG), free concentrations of both hormones are increased progressively in pregnancy. In addition, pregnancy leads to activation of the renin-angiotensin-aldosterone system. Most adrenocortical hormone diagnostic thresholds are not applicable or validated in pregnancy. The management of adrenal insufficiency also needs to reflect the physiologic changes of pregnancy, often requiring increased doses of glucocorticoid and at times mineralocorticoid replacement, especially in the last trimester. In this review, we describe pregnancy induced changes in adrenal function, the diagnosis and management of adrenal insufficiency in pregnancy and areas requiring further research.

New developments and concepts in the diagnosis and management of diabetes insipidus (AVP-deficiency and resistance)

Diabetes insipidus (DI) is a disorder characterised by the excretion of large amounts of hypotonic urine, with a prevalence of 1 per 25,000 population. Central DI (CDI), better now referred to as arginine vasopressin (AVP)-deficiency, is the most common form of DI resulting from deficiency of the hormone AVP from the pituitary. The less common nephrogenic DI (NDI) or AVP-resistance develops secondary to AVP resistance in the kidneys. The majority of causes of DI are acquired, with CDI developing when more than 80% of AVP-secreting neurons are damaged. Inherited/familial CDI causes account for approximately 1% of cases. Although the pathogenesis of NDI is unclear, more than 280 disease-causing mutations affecting the AVP2 protein or AVP V2 receptor, as well as in aquaporin 2 (AQP2), have been described. Although the cAMP/protein kinase A pathway remains the major regulatory pathway of AVP/AQP2 action, in vitro data have also revealed additional cAMP independent pathways of NDI pathogenesis. Diagnosing partial forms of DI, and distinguishing them from primary polydipsia, can be challenging, previously necessitating the use of the water deprivation test. However, measurements of circulating copeptin levels, especially after stimulation, are increasingly replacing the classical tests in clinical practice because of their ease of use and high sensitivity and specificity. The treatment of CDI relies on desmopressin administration, whereas NDI requires the management of any underlying diseases, removal of offending drugs and, in some cases, administration of diuretics. A better understanding of the pathophysiology of DI has led to novel evolving therapeutic agents that are under clinical trial.

Diagnosis and Management of Central Diabetes Insipidus in Adults

Central diabetes insipidus (CDI) is a clinical syndrome which results from loss or impaired function of vasopressinergic neurons in the hypothalamus/posterior pituitary, resulting in impaired synthesis and/or secretion of arginine vasopressin (AVP). AVP deficiency leads to the inability to concentrate urine and excessive renal water losses, resulting in a clinical syndrome of hypotonic polyuria with compensatory thirst. CDI is caused by diverse etiologies, although it typically develops due to neoplastic, traumatic, or autoimmune destruction of AVP-synthesizing/secreting neurons. This review focuses on the diagnosis and management of CDI, providing insights into the physiological disturbances underpinning the syndrome. Recent developments in diagnostic techniques, particularly the development of the copeptin assay, have improved accuracy and acceptability of the diagnostic approach to the hypotonic polyuria syndrome. We discuss the management of CDI with particular emphasis on management of fluid intake and pharmacological replacement of AVP. Specific clinical syndromes such as adipsic diabetes insipidus and diabetes insipidus in pregnancy as well as management of the perioperative patient with diabetes insipidus are also discussed.

Acute Sheehan’s syndrome manifesting initially with diabetes insipidus postpartum: a case report and systematic literature review

Purpose

Acute Sheehan’s syndrome is a rare, but potentially life-threatening, obstetric event that can be complicated by diabetes insipidus. Little information on the diagnosis and treatment of Sheehan’s syndrome with diabetes insipidus is available. We report on a 28-year-old patient who developed acute Sheehan’s syndrome with diabetes insipidus after giving birth, and on a systematic review of similar cases.

Methods

We performed a systematic review of the literature cataloged in PubMed and Google Scholar using the keywords “Sheehan syndrome” OR “Sheehan's syndrome” AND “diabetes insipidus” to identify relevant case reports published between 1990 and 2021. Eight Reports met the inclusion criteria (English-language abstracts available, onset in the puerperium, information about the day of the onset).

Results

In the present case, postpartum curettage was necessary to remove the residual placenta. The total amount of blood loss was severe (2500 ml). On the second day postpartal, the patient developed polyuria. Laboratory analysis revealed hypernatremia with increased serum osmolality and decreased urinary osmolality. Hormone analysis showed partial hypopituitarism involving the thyroid, corticotropic, and gonadotropic axes. The prolactin level was elevated. Brain magnetic resonance imaging showed pituitary gland infarction. Desmopressin therapy was initiated and resolved the polyuria. Hormone replacement therapy was administered. Four months later, the patient was well, with partial diabetes insipidus. The literature review indicated that this case was typical in terms of symptoms and disease onset. Most reported cases involve hypotension and peripartum hemorrhage, but some patients without hemorrhage also develop Sheehan’s syndrome. Elevated prolactin levels are uncommon and associated with poor prognosis in patients with Sheehan’s syndrome.

Conclusion

Acute Sheehan’s syndrome with diabetes insipidus involves nearly all pituitary hormone axes, indicating severe disease. Prolactin elevation could suggest that a case of Sheehan’s syndrome is severe.

Pituitary Stalk Enlargement in Adults

Pathologies involving the pituitary stalk (PS) are generally revealed by the presence of diabetes insipidus. The availability of MRI provides a major diagnostic contribution by enabling the visualization of the site of the culprit lesion, especially when it is small. However, when only an enlarged PS is found, the etiological workup may be difficult, particularly because the biopsy of the stalk is difficult, harmful and often not contributive. The pathological proof of the etiology thus needs to be obtained indirectly. The aim of this article was to provide an accurate review of the literature about PS enlargement in adults describing the differences between the numerous etiologies involved and consequent different diagnostic approaches. The etiological diagnostic procedure begins with the search for possible other lesions suggestive of histiocytosis, sarcoidosis, tuberculosis or other etiologies elsewhere in the body that could be more easily biopsied. We usually perform neck, thorax, abdomen, and pelvis CT scan; positron emission tomography scan; bone scan; or other imaging methods when we suspect generalized lesions. Measurement of serum markers such as human chorionic gonadotropin, alpha-fetoprotein, angiotensin converting enzyme, and IgG4 may also be helpful. Obviously, in the presence of an underlying carcinoma (particularly breast or bronchopulmonary), one must first consider a metastasis located in the PS. In the case of an isolated PS enlargement, simple monitoring, without histological proof, can be proposed (by repeating MRI at 3-6 months) with the hypothesis of a germinoma (particularly in a teenager or a young adult) that, by increasing in size, necessitates a biopsy. In contrast, a spontaneous diminution of the lesion is suggestive of infundibulo-neurohypophysitis. We prefer not to initiate steroid therapy to monitor the spontaneous course when a watch-and-see attitude is preferred. However, in many cases, the etiological diagnosis remains uncertain, requiring either close monitoring of the lesion or, in exceptional situations, trying to obtain definitive pathological evidence by a biopsy, which, unfortunately, is in most cases performed by the transcranial route. If a simple surveillance is chosen, it has to be very prolonged (annual surveillance). Indeed, progression of histiocytosis or germinoma may be delayed.