Iatrogenic [corrected] extrapontine myelinolysis in central diabetes insipidus: are cyclosporine and 1-desamino-8-D-arginine vasopressin harmful in association?

Vasopressin-Dependent Disorders: What Is New in Children?

Arginine vasopressin (AVP)-mediated osmoregulatory disorders, such as diabetes insipidus (DI) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are common in the differential diagnosis for children with hypo- and hypernatremia and require timely recognition and treatment. DI is caused by a failure to concentrate urine secondary to impaired production of or response to AVP, resulting in hypernatremia. Newer methods of diagnosing DI include measuring copeptin levels; copeptin is AVP's chaperone protein and serves as a surrogate biomarker of AVP secretion. Intraoperative copeptin levels may also help predict the risk for developing DI after neurosurgical procedures. Copeptin levels hold diagnostic promise in other pediatric conditions, too. Recently, expanded genotype and phenotype correlations in inherited DI disorders have been described and may better predict the clinical course in affected children and infants. Similarly, newer formulations of synthetic AVP may improve pediatric DI treatment. In contrast to DI, SIADH, characterized by inappropriate AVP secretion, commonly leads to severe hyponatremia. Contemporary methods aid clinicians in distinguishing SIADH from other hyponatremic conditions, particularly cerebral salt wasting. Further research on the efficacy of therapies for pediatric SIADH is needed, although some adult treatments hold promise for pediatrics. Lastly, expansion of home point-of-care sodium testing may transform management of SIADH and DI in children. In this article, we review recent developments in the understanding of pathophysiology, diagnostic workup, and treatment of better outcomes and quality of life for children with these challenging disorders.

Autoimmune central diabetes insipidus in a patient with ureaplasma urealyticum infection and review on new triggers of immune response

Diabetes insipidus is a disease in which large volumes of dilute urine (polyuria) are excreted due to vasopressin (AVP) deficiency [central diabetes insipidus (CDI)] or to AVP resistance (nephrogenic diabetes insipidus). In the majority of patients, the occurrence of CDI is related to the destruction or degeneration of neurons of the hypothalamic supraoptic and paraventricular nuclei. The most common and well recognized causes include local inflammatory or autoimmune diseases, vascular disorders, Langerhans cell histiocytosis (LCH), sarcoidosis, tumors such as germinoma/craniopharyngioma or metastases, traumatic brain injuries, intracranial surgery, and midline cerebral and cranial malformations. Here we have the opportunity to describe an unusual case of female patient who developed autoimmune CDI following ureaplasma urealyticum infection and to review the literature on this uncommon feature. Moreover, we also discussed the potential mechanisms by which ureaplasma urealyticum might favor the development of autoimmune CDI.

Management of diabetes insipidus and adipsia in the child

Central diabetes insipidus (CDI) is a complex and heterogeneous clinical syndrome affecting the hypothalamic-neurohypophyseal network and water balance. A recent national surveillance in Denmark showed a prevalence rate of twenty-three CDI patients per 100,000 inhabitants in five years. The differential diagnosis between several presenting conditions with polyuria and polydipsia is puzzling, and the etiological diagnosis of CDI remains a challenge before the identification of an underlying cause. For clinical practice, a timely diagnosis for initiating specific treatment in order to avoid central nervous system damage, additional pituitary defects and the risk of dissemination of germ cell tumor is advisable. Proper etiological diagnosis can be achieved via a series of steps that start with careful clinical observation of several signs and endocrine symptoms and then progress to more sophisticated imaging tools. This review summarizes the best practice and approach for the diagnosis and treatment of patients with CDI.

Extrapontine myelinolysis associated with pituitrin: case report and literature review

Background

Hyponatremia is the most common electrolyte abnormality encountered in hospitalized patients, resulting from a varied spectrum of conditions. Both the primary disturbance and its correction can result in life-threatening neurological consequences. Extrapontine myelinolysis is one such complication that is associated with the rapid correction of hyponatremia. Here we describe a patient who developed extrapontine myelinolysis unexpectedly after the correction of hyponatremia, which involved the drug pituitrin.

Case presentation

A 24-year-old Chinese woman was transferred to our neurology department with the symptoms of dysarthria and quadriparesis developing one day after the correction of hyponatremia (from 118 mmol/L to 140 mmol/L), which followed with a continuous intravenous drip of pituitrin used to control hemoptysis in the emergency room. During the course, she developed involuntary movement. Magnetic resonance imaging changes were consistent with extrapontine myelinolysis.

Conclusion

This present case describes the mechanism of profound hyponatremia involving pituitrin, and the subsequent development of extrapontine myelinolysis. Physicians may approach effective clinical management of patients through awareness of the adverse effect of pituitrin on serum sodium levels, and avoid rapid correction of hyponatremia in clinical practice.

Central pontine and extrapontine myelinolysis in children: a review of 76 patients

This study aimed to identify the causes and contributing factors, neurologic presentation, and outcomes of central pontine and extrapontine myelinolysis and to examine any trends in the presentation and course of these disorders over the past 50 years. Seventy-six pediatric cases were identified in the literature. Age, sex, decade of diagnosis, neurologic presentation, outcome, and attributed causes were extracted. The results showed that the diagnosis, course, and outcomes of central pontine and extrapontine myelinolysis clearly have changed over the past few decades. Early cases generally were diagnosed at autopsy as opposed to computed tomography or magnetic resonance imaging more recently. Ninety-four percent of cases prior to 1990 and only 7% of cases from 1990 onward resulted in patient mortality. The decade in which the case was reported was the strongest predictor of outcome (P < .001), followed by sodium dysregulation (P = .045) and dehydration (P = .07).

Diabetes insipidus in children: pathophysiology, diagnosis and management

In diabetes insipidus, the amount of water ingested and the quantity and concentration of urine produced needs to be carefully regulated if fluid volume and osmolality are to be maintained within the normal range. One of the principal mechanisms controlling urine output is vasopressin which is released from the posterior pituitary gland and enhances water reabsorption from the renal collecting duct. In diabetes insipidus, the excessive production of dilute urine, and the causes of this clinical picture can be divided into three main groups: the first is primary polydipsia where the amount of fluid ingested is inappropriately large; the second group is cranial diabetes insipidus where the production of vasopressin is abnormally low; and, the third group is nephrogenic diabetes insipidus where the kidney response to vasopressin is impaired. The history and examination may suggest an underlying explanation for diabetes insipidus but a range of baseline and more extensive investigations may be required before a diagnosis can be reached. These investigations are not without risk, and the results need to be interpreted carefully because children do not always segregate neatly into a particular diagnostic category on the basis of one test alone. Children with cranial diabetes insipidus typically respond to arginine vasopressin or its manufactured analogue, desmopressin, with an increase in urine osmolality and an associated reduction in urine output. Such children usually require neuroimaging to look for evidence of evolving CNS pathology, such as an intracranial tumour. Vasopressin "replacement" with desmopressin is the treatment of choice in patients with cranial diabetes insipidus although extreme caution is required when treating babies or small children because of the danger of fluid overload. Abnormal production of other pituitary hormones in children with CNS disease can also influence fluid balance. Nephrogenic diabetes insipidus can be due to abnormal electrolyte concentrations, therefore these should be measured as part of the initial assessment. In a small number of children the defect is a primary abnormality of the vasopressin receptor or one of the water channel proteins (aquaporins) involved in water transport. The treatment of these patients is difficult and typically involves therapy with a diuretic such as chlorothiazide, as well as indomethacin. These agents enhance urine osmolality by their effect on circulating volume and renal solute and water handling. The fluid intake of most young children with primary polydipsia can be safely reduced to a more appropriate level.

Dynamic endocrine testing and magnetic resonance imaging in the long-term follow-up of childhood langerhans cell histiocytosis

Children treated for Langerhans cell histiocytosis (LCH) are at risk for short and long term endocrine sequelae, but biological predictors of specific deficits are not well defined. We evaluated the frequency and progression of LCH-related endocrine deficits during long term follow-up and assessed the ability of dynamic endocrine testing to identify patients at risk for late anterior or posterior pituitary hormone dysfunction. The 17 patients (5 males and 12 females) were followed a median of 10 yr after diagnosis of single system (n = 6) or multisystem (n = 11) disease. Study evaluations, performed a median of 4.1 yr after the diagnosis, comprised pituitary hormone responses to the appropriate challenge, 7-h water deprivation test, 3% hypertonic saline infusion, and magnetic resonance imaging (MRI). The six patients with GH deficiency at the time of evaluation had a significantly lower GH response to GHRH than the other patients [median peak, 7.3 vs. 21.5 micrograms/L (P = 0.03); median area under the curve, 4.7 vs. 13.5 micrograms/L (P = 0.03)]; levels in the latter group did not differ significantly from those in 20 age- and sex-matched controls with constitutional or familial short stature. Two patients who had GH responses to GHRH of 20.6 and 23 ng/mL at 2.8 and 9.5 yr of age developed GH deficiency at 6.5 and 11.2 yr of age, respectively. The TSH response to TRH was less than 10 mU/L in three patients, two of whom later developed central hypothyroidism. ACTH and cortisol responses to CRF, and PRL responses to TRH were normal in all cases, and LH and FSH responses to GnRH were compatible with pubertal stage. Abnormalities in arginine vasopressin responses to water deprivation or hypertonic saline infusion were seen only in four patients who had preexisting diabetes insipidus (DI); one patient who later developed DI had normal findings. On standard MRI, posterior pituitary hyperintensity was absent only in the patients with DI. Pituitary stalk thickening was seen in seven patients, including three who did not have DI and had normal arginine vasopressin responses. Delayed posterior and anterior enhancement on dynamic MRI was present in two patients, both of whom later developed central hypothyroidism. Patients with single system disease had a lower 5-yr probability of LCH reactivation (41% vs. 83% for those with multisystem disease; P = 0.21) and a significantly lower risk of endocrine dysfunction (P = 0.007). In this series, dynamic evaluation of pituitary function was not a useful predictor of late endocrine sequelae, with the possible exception of the progressively decreasing TSH response to TRH. Similarly, a standard MRI was not predictive, although dynamic imaging may be informative regarding evolving pituitary hormone deficiency.