The management of central diabetes insipidus in infancy: desmopressin, low renal solute load formula, thiazide diuretics

Idiopathic partial central diabetes insipidus

Diabetes insipidus is a rare disorder characterized by the inability to concentrate urine, which results in hypotonic urine and increased urinary volume. It may occur because of antidiuretic hormone deficiency or resistance to its action in the renal tubules. When there is a deficiency in the synthesis of antidiuretic hormones, diabetes insipidus is called central; when there is resistance to its action in the renal tubules, it is said to be nephrogenic. We report a case of idiopathic partial central diabetes insipidus and highlight the management and treatment of the disease.

Sodium Homeostasis, a Balance Necessary for Life

Body sodium (Na) levels must be maintained within a narrow range for the correct functioning of the organism (Na homeostasis). Na disorders include not only elevated levels of this solute (hypernatremia), as in diabetes insipidus, but also reduced levels (hyponatremia), as in cerebral salt wasting syndrome. The balance in body Na levels therefore requires a delicate equilibrium to be maintained between the ingestion and excretion of Na. Salt (NaCl) intake is processed by receptors in the tongue and digestive system, which transmit the information to the nucleus of the solitary tract via a neural pathway (chorda tympani/vagus nerves) and to circumventricular organs, including the subfornical organ and area postrema, via a humoral pathway (blood/cerebrospinal fluid). Circuits are formed that stimulate or inhibit homeostatic Na intake involving participation of the parabrachial nucleus, pre-locus coeruleus, medial tuberomammillary nuclei, median eminence, paraventricular and supraoptic nuclei, and other structures with reward properties such as the bed nucleus of the stria terminalis, central amygdala, and ventral tegmental area. Finally, the kidney uses neural signals (e.g., renal sympathetic nerves) and vascular (e.g., renal perfusion pressure) and humoral (e.g., renin-angiotensin-aldosterone system, cardiac natriuretic peptides, antidiuretic hormone, and oxytocin) factors to promote Na excretion or retention and thereby maintain extracellular fluid volume. All these intake and excretion processes are modulated by chemical messengers, many of which (e.g., aldosterone, angiotensin II, and oxytocin) have effects that are coordinated at peripheral and central level to ensure Na homeostasis.

Fluid management in hospitalized pediatric patients

The proper use of intravenous fluids has likely been responsible for saving more lives than any other group of substances. Proper use includes prescribing an appropriate electrolyte and carbohydrate solution, at a calculated rate or volume, for the right child, at the right time. Forming intravenous fluid plans for hospitalized children requires an understanding of water and electrolyte physiology in healthy children and how different pathology deviates from the norm. This review highlights fluid management in several disease types, including liver disease, diabetic ketoacidosis, syndrome of inappropriate antidiuretic hormone, diabetes insipidus, kidney disease, and intestinal failure as well as in those with nonphysiologic fluid losses. For each disease, the review discusses specific considerations, evaluations, and management strategies to consider when customizing intravenous fluid plans. Ultimately, all hospitalized children should receive an individualized fluid plan with recurrent evaluations and fluid modifications to provide optimal care.

Management of Diabetes Insipidus following Surgery for Pituitary and Suprasellar Tumours

Central diabetes insipidus (CDI) is a common complication after pituitary surgery. However, it is most frequently transient. It is defined by the excretion of an abnormally large volume of dilute urine with increasing serum osmolality. The reported incidence of CDI after pituitary surgery ranges from 0–90%. Large tumour size, gross total resection and intraoperative cerebrospinal fluid leak usually pose an increased risk of CDI as observed with craniopharyngioma and Rathke’s cleft cysts. CDI can be associated with high morbidity and mortality if not promptly recognised and treated on time. It is also essential to rule out other causes of postoperative polyuria to avoid unnecessary pharmacotherapy and iatrogenic hyponatremia. Once the diagnosis of CDI is established, close monitoring is required to evaluate the response to treatment and to determine whether the CDI is transient or permanent. This review outlines the evaluation and management of patients with CDI following pituitary and suprasellar tumour surgery to help recognise the diagnosis, consider the differential diagnosis, initiate therapeutic interventions and guide monitoring and long-term management.

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.

Management of transient central diabetes insipidus with intravenous desmopressin in a premature infant with gastroschisis and septo-optic dysplasia: A case report

Central diabetes insipidus (CDI) may occur in the setting of intracranial abnormalities that affect the hypothalamus-pituitary system. It occurs rarely in neonates, especially in the premature population, and represents a challenging disease process to treat pharmacologically. Little is known regarding the treatment options in premature infants, including dose and route of administration of intravenous desmopressin (DDAVP). We present a case of a late premature male infant with gastroschisis and septo-optic dysplasia who developed transient CDI. He was treated with intravenous DDAVP but required frequent laboratory monitoring and a multidisciplinary approach, and ultimately his CDI resolved. Although there are minimal guidelines regarding the appropriate formulation and dosage of DDAVP for management of CDI in infants, we initiated the lowest dose available and titrated the medication based on close monitoring of urine output and serum sodium levels in order to successfully treat his transient CDI.

Animal models for diabetes insipidus

The hormone arginine vasopressin (AVP) is a nonapeptide synthesized by hypothalamic magnocellular nuclei and secreted from the posterior pituitary into the bloodstream. It binds to AVP receptor 2 in the kidney to promote the insertion of aquaporin channels (AQP2) and antidiuretic responses. AVP secretion deficits produce central diabetes insipidus (CDI), while renal insensitivity to the antidiuretic effect of AVP causes nephrogenic diabetes insipidus (NDI). Hereditary and acquired forms of CDI and NDI generate hypotonic polyuria, polydipsia, hyperosmolality, and hypernatremia. The AVP mutant (Brattleboro) rat is the principal animal model of hereditary CDI, while neurohypophysectomy, pituitary stalk compression, hypophysectomy, and mediobasal hypothalamic lesions produce acquired CDI. In animals, hereditary NDI is mainly caused by mutations in AVP2R or AQP2 genes, while acquired NDI is most frequently induced by lithium. We report here on the determinants of the intake and excretion of water and mineral salts and on the different types of DI in humans. We then describe the hydromineral characteristics of these animal models and the responses observed after administration of hypertonic NaCl or when they are fed with low-sodium diets. Finally, we report on the effects of drugs such as AVP analogues and/or oxytocin, another neuropeptide that increases sodium excretion in animal models and humans with CDI, and sildenafil, a compound that increases the expression and function of AQP2 channels in animal models and humans with NDI.

Use of Chlorothiazide in the Management of Central Diabetes Insipidus in Early Infancy

Management of central diabetes insipidus in infancy is challenging. The various forms of desmopressin, oral, subcutaneous, and intranasal, have variability in the duration of action. Infants consume most of their calories as liquids which with desmopressin puts them at risk for hyponatremia and seizures. There are few cases reporting chlorothiazide as a temporizing measure for central diabetes insipidus in infancy. A male infant presented on day of life 30 with holoprosencephaly, cleft lip and palate, and poor weight gain to endocrine clinic. Biochemical tests and urine output were consistent with central diabetes insipidus. The patient required approximately 2.5 times the normal fluid intake to keep up with the urine output. Patient was started on low renal solute load formula and oral chlorothiazide. There were normalization of serum sodium, decrease in fluid intake close to 1.3 times the normal, and improved urine output. There were no episodes of hyponatremia/hypernatremia inpatient. The patient had 2 episodes of hypernatremia in the first year of life resolving with few hours of hydration. Oral chlorothiazide is a potential bridging agent for treatment of central DI along with low renal solute load formula in early infancy. It can help achieve adequate control of DI without wide serum sodium fluctuations.

Diabetes insipidus in infants and children

Diabetes insipidus, the inability to concentrate urine resulting in polyuria and polydipsia, can have different manifestations and management considerations in infants and children compared to adults. Central diabetes insipidus, secondary to lack of vasopressin production, is more common in children than is nephrogenic diabetes insipidus, the inability to respond appropriately to vasopressin. The goal of treatment in both forms of diabetes insipidus is to decrease urine output and thirst while allowing for appropriate fluid balance, normonatremia and ensuring an acceptable quality of life for each patient. An infant's obligate need to consume calories as liquid and the need for readjustment of medication dosing in growing children both present unique challenges for diabetes insipidus management in the pediatric population. Treatment modalities typically include vasopressin or thiazide diuretics. Special consideration must be given when managing diabetes insipidus in the adipsic patient, post-surgical patient, and in those undergoing chemotherapy or receiving medications that alter free water clearance.

Etiological and clinical characteristics of central diabetes insipidus in children: a single center experience

Background

Central diabetes insipidus (CDI) results from a number of conditions affecting the hypothalamic-neurohypophyseal system to cause vasopressin deficiency. Diagnosis of CDI is challenging, and clinical data and guidelines for management are lacking. We aim to characterize clinical and radiological characteristics of a cohort of pediatric patients with CDI.

Methods

A chart review of 35 patients with CDI followed at North Carolina Children’s Hospital from 2000 to 2015 was undertaken. The frequencies of specific etiologies of CDI and characteristic magnetic resonance imaging (MRI) findings were determined. The presence of additional hormone deficiencies at diagnosis and later in the disease course was ascertained. Patient characteristics and management strategies were evaluated.

Results

The cohort included 14 female and 21 male patients with a median age of 4.7 years (range, less than 1 month to 16 years) at diagnosis. Median duration of follow-up was 5 years (range, 2 months to 16 years). The cause of CDI was intracranial mass in 13 patients (37.2 %), septo-optic dysplasia in 9 patients (25.7 %), holoprosencephaly in 5 patients (14.2 %), Langerhans cell histiocytosis in 3 patients (8.6 %), isolated pituitary hypoplasia in 2 patients (5.7 %), and encephalocele in 1 patient (2.9 %). Patients were symptomatic for a mean of 6.3 months (range, less than 1 month to 36 months) prior to diagnosis of CDI. Growth hormone (GH), thyrotropin (TSH), adrenocorticotropic hormone (ACTH), and gonadotropin deficiencies were present at diagnosis in 34, 23, 23, and 6 % of patients, respectively. GH, TSH, ACTH, and gonadotropin deficiencies were diagnosed during follow-up in 23, 40, 37, and 14 % of patients, respectively. In patients with structural CNS abnormalities, development of additional hormone deficiencies occurred anywhere from 2 months to 13 years after the time of initial presentation.

Conclusions

All patients in our cohort had an underlying organic etiology for CDI, with intracranial masses and CNS malformations being most common. Therefore, MRI of the brain is indicated in all pediatric patients with CDI. Other pituitary hormone deficiencies should be investigated at diagnosis as well as during follow-up.

Thiazide Diuretics in the Management of Young Children with Central Diabetes Insipidus

OBJECTIVE

To report our experience in treating infants and toddlers with central diabetes insipidus (DI) with thiazide diuretics.

STUDY DESIGN

A retrospective chart review of all infants and toddlers who were treated with thiazide diuretics for central DI at the Mayo Clinic between 1996 and 2014.

RESULTS

Our cohort consisted of 13 patients. The median age at the start of therapy was 6 months (IQR, 1-14 months). Eight patients were given chlorothiazide at a starting dose of 5-10 mg/kg/day, and 5 patients were treated with hydrochlorothiazide at a starting dose of 1-2 mg/kg/day. The median age at the cessation of thiazide therapy was 18 months (IQR, 11.5-39 months). The main reason for stopping was the lack of continued response, in addition to hypernatremia. There was no hospitalization secondary to hyponatremia and only 1 hospitalization secondary to hypernatremia while receiving thiazide therapy. Calcium was checked periodically in 7 of the 13 patients, and 2 of these 7 patients had persistent hypercalcemia.

CONCLUSION

Thiazide diuretics appear to be safe and effective in treating infants with central DI. They can be continued after the introduction of solid food, and until a lack of response is observed.

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.

Diabetes insipidus: celebrating a century of vasopressin therapy

Diabetes mellitus, widely known to the ancients for polyuria and glycosuria, budded off diabetes insipidus (DI) about 200 years ago, based on the glucose-free polyuria that characterized a subset of patients. In the late 19th century, clinicians identified the posterior pituitary as the site of pathology, and pharmacologists found multiple bioactivities there. Early in the 20th century, the amelioration of the polyuria with extracts of the posterior pituitary inaugurated a new era in therapy and advanced the hypothesis that DI was due to a hormone deficiency. Decades later, a subset of patients with polyuria unresponsive to therapy were recognized, leading to the distinction between central DI and nephrogenic DI, an early example of a hormone-resistant condition. Recognition that the posterior pituitary had 2 hormones was followed by du Vigneaud's Nobel Prize winning isolation, sequencing, and chemical synthesis of oxytocin and vasopressin. The pure hormones accelerated the development of bioassays and immunoassays that confirmed the hormone deficiency in vasopressin-sensitive DI and abundant levels of hormone in patients with the nephrogenic disorder. With both forms of the disease, acquired and inborn defects were recognized. Emerging concepts of receptors and of genetic analysis led to the recognition of patients with mutations in the genes for 1) arginine vasopressin (AVP), 2) the AVP receptor 2 (AVPR2), and 3) the aquaporin 2 water channel (AQP2). We recount here the multiple skeins of clinical and laboratory research that intersected frequently over the centuries since the first recognition of DI.

Desmopressin lyophilisate for the treatment of central diabetes insipidus: first experience in very young infants

INTRODUCTION

In neonates and small infants, early diagnosis of central diabetes insipidus (CDI) and treatment with desmopressin in low doses (avoiding severe hypo- or hypernatremia) are important to prevent associated high morbidity and mortality in this particular age group.

CASE PRESENTATION

We described pharmacokinetic and pharmacodynamic results of the use of recently launched oral desmopressin lyophilisate (Minirin Melt®) in two infants with CDI, diagnosed at the age of 12 and 62 days, respectively. We observed that a starting dose of 60 μg of Minirin Melt® in the first case resulted in a pharmacokinetic profile largely exceeding the reference frame observed in children with nocturnal enuresis, while a dose of 15 μg in the second case resulted in acceptable concentrations. After initial dose adjustments, administration of sublingual lyophilisate resulted in rather stable serum sodium concentrations.

CONCLUSIONS

Using Minirin Melt® in infants with CDI appears to be effective, easy to use and well tolerated.

Efficacy of Hydrochlorothiazide and low renal solute feed in Neonatal Central Diabetes Insipidus with transition to Oral Desmopressin in early infancy

BACKGROUND

The treatment of central diabetes insipidus (DI) with desmopressin in the neonatal period is challenging because of the significant risk of hyponatremia with this agent. The fixed anti-diuresis action of desmopressin and the obligate high fluid intake with milk feeds lead to considerable risk of water intoxication and hyponatremia. To reduce this risk, thiazide diuretics, part of the treatment of nephrogenic DI, were used in conjunction with low renal solute feed and were effective in a single case series of neonatal central DI.

AIM

We evaluated the efficacy of early treatment of neonatal central DI with hydrochlorothiazide with low solute feed and investigated the clinical indicators for transition to desmopressin during infancy.

METHODS

A retrospective chart review was conducted at Princess Margaret Hospital, Perth of neonates diagnosed with central DI and treated with hydrochlorothiazide, between 2007 and 2013. Four newborns were identified. Mean sNa and mean change in sNa with desmopressin and hydrochlorothiazide treatment were recorded along with episodes of hyponatremia and hypernatremia. Length and weight trajectories during the first 12 months were assessed.

RESULTS

The mean change in sNa per day with hydrochlorothiazide and low renal solute feed was 2.5 - 3 mmol/L; on desmopressin treatment, the mean change in sNa was 6.8-7.9 mmol/L. There was one episode of symptomatic hyponatremia with intranasal desmopressin with no episodes of hyponatremia or hypernatremia during treatment with hydrochlorothiazide or following transition to oral desmopressin. Transition to oral desmopressin between 3 to 12 months of age was associated with good control of DI. Following introduction of solids, sNa remained stable but weight gain was slow. This improved following transition to desmopressin in one infant.

CONCLUSIONS

Hydrochlorothiazide with low renal solute feed is a safe and effective treatment option in neonatal central DI. However, transition to desmopressin should be considered early in infancy following initiation of solids to facilitate growth.

[Importance of long-term follow-up of diabetes insipidus; from lymphocytic hypophysitis to germinoma]

A case is presented of a 10-year old boy who had a hypothalamic-pituitary axis disorder. He initially presented with diabetes insipidus that progressed to panhypopituitarism. A hidden hypothalamic lesion should be suspected in all these cases, and should be followed up. New lesions were found in the pituitary stem three years later. Although tumor markers were negative, there was an increase in size, and a biopsy was performed. The histopathology reported a Lymphocytic Hypophysitis. There were increases in the tumor markers during the follow-up, thus a second biopsy was performed, with the diagnosis of Germinoma. Lymphocytic Hypophysitis is an uncommon diagnosis in children. Few cases have been reported, and in some cases, they were later diagnosed with Germinoma. We believe this case highlights the importance of the follow-up of children with Central Diabetes Insipidus with a normal MRI, as well as not taking the diagnosis of Lymphocytic Hypophysitis/lymphocytic Infundibular neurohypophysitis as definitive, as it is a rare diagnosis at this age, and could mask a Germinoma, as recorded in some cases.

Clinical characteristics and management of cranial diabetes insipidus in infants

AIM

Cranial diabetes insipidus (CDI) is rare in infants with no guidelines on its management. We describe the first case series, characterizing the clinical features and treatment challenges.

METHOD

Retrospective case note review of infants diagnosed with CDI between April 1992 and February 2011.

RESULTS

Nineteen infants (52% male) were identified. Eight were born preterm. Median (range) age at diagnosis was 24 days (5-300); preterm babies were younger at diagnosis (21 vs. 46 days). In 58% (11/19) of infants, hypernatraemia was discovered incidentally. In 37% of cases there was associated midline anomalies, however, only four patients (21%) had absent posterior pituitary signal on a magnetic resonance imaging brain scan. The most frequent (5/19) underlying diagnosis was septo-optic dysplasia. Eight patients had isolated CDI and 11 had multiple pituitary hormone deficiencies. Isolated CDI tended to be more common in preterm, compared to term babies (p=0.11). Des-amino arginine vasopressin (DDAVP) was administered intranasally in eight and orally in 11 infants. Plasma sodium nadir following DDAVP administration was lower following intranasal compared to an oral route of administration (median: 128 vs. 133 mmol/L, p=0.022). No cases resolved on follow-up.

CONCLUSIONS

CDI in infants is often diagnosed incidentally. Aetiology, clinical, and imaging features are very variable, with some differences between preterm and term infants. Oral DDAVP appears to be superior to intranasal with less pronounced serum sodium fluctuations.

Desmopressin administration in children with central diabetes insipidus: a retrospective review

BACKGROUND

Central diabetes insipidus (DI) is a rare disorder in children caused by a deficiency of antidiuretic hormone arginine (vasopressin). Desmopressin is the first line agent in management of central DI. However, one of the side effects of desmopressin is water intoxication and hyponatraemia. This study reviews the patterns of desmopressin use and side effects in our institution.

METHODS

Retrospective chart review of all patients with central DI followed up in one tertiary centre between 1 January 2008 and 31 December 2010.

RESULTS

Forty-one patients (22 males and 19 females) were included. Twelve patients (29.3%) had congenital and 29 patients (70.7%) had acquired DI, mostly as a result of intracranial tumours. Thirty-six (87.8%) patients were on oral desmopressin and the remaining on nasal formulation. The median oral dose was 9.5 (4.2-17.0) μg/kg/day with median frequency of 2.5 (2-3). The median nasal dose was 0.7 (0.4-1.4) μg/kg/day with median frequency of 2.0 (2-3.5). Fourteen patients (34.1%) were switched from nasal to oral desmopressin with the median dose conversion factor of 20.1 (10.7-31.8). Forty percent of patients on nasal desmopressin experienced hypo/hypernatraemia compared to 18.1% on oral, however, there were no significance difference between standardized hypo/hypernatraemia episodes per treatment year.

CONCLUSIONS

Oral desmopressin is used in the majority of our patients including infants and toddlers. There is wide inter-individual variation in dose requirement and dosing intervals. Management of central diabetes insipidus remains a challenge in adipsic patients and in young children during intercurrent illness regardless of the desmopressin formulation.

Home blood sodium monitoring, sliding-scale fluid prescription and subcutaneous DDAVP for infantile diabetes insipidus with impaired thirst mechanism

Background/Aims

Infants with diabetes insipidus (DI), especially those with impaired thirst mechanism or hypothalamic hyperphagia, are prone to severe sodium fluctuations, often requiring hospitalization. We aimed to avoid dangerous fluctuations in serum sodium and improve parental independence.

Methods

A 16-month old girl with central DI, absent thirst mechanism and hyperphagia following surgery for hypothalamic astrocytoma had erratic absorption of oral DDAVP during chemotherapy cycles. She required prolonged hospitalizations for hypernatremia and hyponatremic seizure. Intensive monitoring of fluid balance, weight and clinical assessment of hydration were not helpful in predicting serum sodium. Discharge home was deemed unsafe. Oral DDAVP was switched to subcutaneous (twice-daily injections, starting with 0.01mcg/dose, increasing to 0.024mcg/dose). The parents adjusted daily fluid allocation by sliding-scale, according to the blood sodium level (measured by handheld i-STAT analyser, Abbott). We adjusted the DDAVP dose if fluid allocation differed from maintenance requirements for 3 consecutive days.

Results

After 2.5 months, sodium was better controlled, with 84% of levels within reference range (135-145 mmol/L) vs. only 51% on the old regimen (p = 0.0001). The sodium ranged from 132-154 mmol/L, compared to 120–156 on the old regimen. She was discharged home.

Conclusion

This practical regimen improved sodium control, parental independence, and allowed discharge home.

Management of diabetes insipidus in children

Diabetes Insipidus (DI) is a heterogeneous clinical syndrome of disturbance in water balance, characterized by polyuria (urine output > 4 ml/kg/hr), polydypsia (water intake > 2 L/m(2)/d) and failure to thrive. In children, Nephrogenic DI (NDI) is more common than Central DI (CDI), and is often acquired. The signs and symptoms vary with etiology, age at presentation and mode of onset. Neonates and infants with NDI are severely affected and difficult to treat. Diagnosis is based on the presence of high plasma osmolality and low urinary osmolality with significant water diuresis. Water deprivation test with vasopressin challenge, though has limitations, is done to differentiate NDI and CDI and diagnose their partial forms. Measurement of urinary aquaporin 2 and serum copeptin levels are being studied and show promising diagnostic potential. Magnetic Resonance Imaging (MRI) pituitary helps in the etiological diagnosis of CDI, absence of posterior pituitary bright signal being the pathognomic sign. If pituitary stalk thickening of < 2 mm is present, these children need to be monitored for evolving lesion. Neonates and young infants are better managed with fluids alone. Older children with CDI are treated with desmopressin. The oral form is safe, highly effective, with more flexibility of dosing and has largely replaced the intranasal form. In NDI besides treatment of the underlying cause, use of high calorie low solute diet and drugs to ameliorate water excretion (thiazide, amelioride, indomethacin) are useful. Children with NDI however well treated, remain short and have mental retardation on follow up.

Practical management of nocturia in urology

Until last decades, nocturia has been considered as an irritative symptom of benign prostatic hyperplasia (BPH), but the nocturia is unresponsive symptoms to various modalities of BPH treatment. More recently, it has been recognized that the prostate is not so quite important as previously believed, as nocturia is equally common in women. The understanding of nocturia has been much changed in last decade; it is a highly prevalent condition, and symptoms in men and women are really no different either quantitatively or qualitatively. The successful introduction of desmopressin (l-deamino-8-D-arginine vasopressin, DDAVP) to decrease nocturnal urine output in severe nocturia which resistant to conventional BPH treatment and in women demonstrated new perspectives in management of nocturia. We reviewed the definition and etiologies of nocturia, offering the current diagnostic procedures and standards of care.

Differentiating appropriate antidiuretic hormone secretion, inappropriate antidiuretic hormone secretion and cerebral salt wasting: the common, uncommon, and misnamed

PURPOSE OF REVIEW

Causes of hyponatremia in children include the syndrome of appropriate antidiuretic hormone secretion, the syndrome of inappropriate antidiuretic hormone secretion and cerebral salt wasting. The purpose of this review is to distinguish these possibilities, focusing on cerebral salt wasting.

RECENT FINDINGS

Most cases of hyponatremia in children are due to the syndrome of appropriate antidiuretic hormone secretion. The syndrome of inappropriate antidiuretic hormone secretion can be seen with neurological injury, pain and medication use. Recent studies suggest that cerebral salt wasting is a rare cause of hyponatremia. When cerebral salt wasting is diagnosed, it is often difficult to make a direct link with the central nervous system insult.

SUMMARY

The clinical condition, assessment of extracellular fluid space volume status, measurement of urinary electrolytes and responses to infusion of saline solutions can distinguish between syndrome of appropriate antidiuretic hormone secretion, syndrome of inappropriate antidiuretic hormone secretion and cerebral salt wasting. The word 'cerebral' in 'cerebral salt wasting syndrome' can thus be inappropriate, conveying inaccurate causation.