Water Intoxication in a Patient With the Prader-Willi Syndrome Treated With Desmopressin for Nocturnal Enuresis

Three pediatric cases of symptomatic hyponatremia in Prader-Willi syndrome

OBJECTIVES

A recent large retrospective cohort study of cases of hyponatremia in Prader-Willi syndrome (PWS), conducted at nine reference centers, showed that severe hyponatremia was rare in PWS (0.5%); furthermore, all cases involved adults. Here, we describe three pediatric cases of severe hyponatremia in PWS, with neurological symptoms.

CASE PRESENTATION

The cases involved two girls and one boy, and only one patient showed uniparental disomy. All patients had hyponatremia during infancy and presented with clinical symptoms, such as convulsions. All three patients improved with intravenous fluids and fluid restriction, with no sequelae.

CONCLUSIONS

We report three pediatric cases of symptomatic hyponatremia of unknown cause in PWS. In patients with PWS, especially those with neurological symptoms such as convulsions, it is necessary to take hyponatremia into consideration.

Hyponatremia in Children and Adults with Prader-Willi Syndrome: A Survey Involving Seven Countries

In Prader–Willi syndrome (PWS), conditions that are associated with hyponatremia are common, such as excessive fluid intake (EFI), desmopressin use and syndrome of inappropriate antidiuretic hormone (SIADH) caused by psychotropic medication. However, the prevalence of hyponatremia in PWS has rarely been reported. Our aim was to describe the prevalence and severity of hyponatremia in PWS. In October 2020, we performed a retrospective study based on the medical records of a large cohort of children and adults with PWS from seven countries. Among 1326 patients (68% adults), 34 (2.6%) had at least one episode of mild or moderate hyponatremia (125 ≤ Na < 135 mmol/L). The causes of non-severe hyponatremia were often multi-factorial, including psychotropic medication in 32%, EFI in 24% and hyperglycemia in 12%. No obvious cause was found in 29%. Seven (0.5%) adults experienced severe hyponatremia (Na < 125 mmol/L). Among these, five recovered completely, but two died. The causes of severe hyponatremia were desmopressin treatment for nocturnal enuresis (n = 2), EFI (n = 2), adrenal insufficiency (n = 1), diuretic treatment (n = 1) and unknown (n = 1). In conclusion, severe hyponatremia was very rare but potentially fatal in PWS. Desmopressin treatment for nocturnal enuresis should be avoided. Enquiring about EFI and monitoring serum sodium should be included in the routine follow-ups of patients with PWS.

Case report: severe asymptomatic hyponatremia in Prader-Willi Syndrome

BACKGROUND

Prader-Willi syndrome is a complex neurogenetic, multisystem disorder. Despite the variable endocrine abnormalities and hypothalamic-pituitary axis dysfunction, hyponatremia has been reported in only a few PWS patients. In previously reported PWS individuals, hyponatremia was associated with abnormal fluid intake or during desmopressin treatment.

CASE PRESENTATION

We describe an infant with Prader-Willi syndrome who had severe, prolonged asymptomatic hyponatremia without a history of excessive fluid intake or desmopressin treatment. We compare the findings with those of the few other reported cases and describe, for the first time, results of a hypertonic saline infusion test and studies of adrenal cortical function.

CONCLUSION

Hyponatremia should be suspected in children with Prader-Willi syndrome, especially in infants with severe failure to thrive. Further studies are needed to determine the pathophysiology of hyponatremia in this syndrome.

Severe signs of hyponatremia secondary to desmopressin treatment for enuresis: a systematic review

OBJECTIVE

Dilutional hyponatremia is a serious adverse effect of desmopressin, a vasopressin analog that is widely prescribed to manage monosymptomatic enuresis. The presentation of hyponatremia, largely related to cerebral dysfunction, can include severe signs like altered mental status and seizures.

METHODS

We reviewed the literature dealing with altered mental status or seizures in enuretic subjects on desmopressin. The retained publications included patients who were described individually, revealing data on mode of administration, further identifiable factors predisposing to hyponatremia, presentation and clinical course.

RESULTS

We found 54 cases of hyponatremia secondary to desmopressin treatment presenting with altered mental status or seizures. In most cases the complication developed 14 days or less after starting desmopressin. An intranasal formulation had been used in 47 patients. Excess fluid intake was documented as a contributing factor in at least 22 cases. In 6 cases severe signs of hyponatremia developed in the context of intercurrent illnesses.

CONCLUSION

Altered mental status or seizures are very rare but recognized complications of desmopressin in enuresis. This complication mostly develops in subjects managed with the intranasal formulation 14 days or less after starting the medication, following excess fluid intake and during intercurrent illnesses.

Desmopressin is a safe drug for the treatment of enuresis

OBJECTIVE

To verify the safety of desmopressin treatment and its associated side-effects in a large number of patients.

MATERIAL AND METHODS

The study was conducted in accordance with the guidelines of the Italian Club for Nocturnal Enuresis, whose criteria are: age >5 years; absence of malformations and infections of the urinary tract; absence of psychological disorders or neurological alterations; number of "wet nights" >5-7; control of liquid intake during the afternoon and evening; monitoring of serum electrolytes before beginning treatment; control of body weight before the beginning of treatment and during the first 4-5 days of therapy; and the informed consent of the parents. The therapeutic regimen provided for a maximum dose of desmopressin of 40 microg/day (four puffs/nostril or two tablets), starting from an initial dosage of 20 microg/day (two puffs/nostril or one tablet) 1 h before going to bed. The study involved two groups of patients with monosymptomatic enuresis: some of them had been administered desmopressin in the form of a spray and others in the form of tablets.

RESULTS

A small percentage of patients presented mild, transient side-effects; in no case were severe side-effects verified.

CONCLUSION

Desmopressin is a safe drug with a low incidence of side-effects.

Water intake and risk of hyponatraemia in Prader-Willi syndrome

BACKGROUND AND METHODS

Unusual water intake and drinking behaviour has occasionally been observed in individuals with Prader-Willi syndrome (PWS). The aim of this study is to explore whether this observation is a part of the PWS phenotype and what the consequences may be. The parents of 51 individuals with PWS (age range 2-40 years) were asked by questionnaire to answer on past and present water intake, drinking behaviour, fluid preferences and medical treatment in their PWS-affected and unaffected children. Questionnaires with information on 47 PWS individuals and 17 without PWS were returned for analysis. The questionnaire information was complemented with information from the individual's medical records. Siblings to PWS individuals made up the control group. The study was approved by the regional medical research ethics committee.

RESULTS

During infancy, 36 (76%) individuals with PWS disliked water without any flavouring and had an extremely small daily intake of water. Seven individuals (15%) increased the daily water intake to unusually high amounts. In 45 the clinical PWS diagnosis was confirmed by molecular (genetic) testing: nine of them with a confirmed PWS diagnosis had a deletion of chromosome 15q11-13, in nine individuals no deletion was identified. The majority of individuals who increased their water consumption to extreme values belonged to the non-deletion group. Two in the non-deletion group developed hyponatraemia while receiving psychiatric medication.

CONCLUSIONS

Infants with PWS seem to be predisposed to unusual drinking behaviour. They dislike and have an unusually small intake of pure water without flavouring, and most of them continue this even after infancy. Some individuals, especially those without deletion, increase their fluid intake and also accept pure water. They have an increased risk of developing water retention and severe hyponatraemia if exposed to medication known to cause side effects like the syndrome of inappropriate antidiuretic hormone secretion. Perhaps this behaviour is just secondary to overeating; perhaps it is a result of a dysfunction of the hypothalamic nuclei engaged in antidiuretic hormone production.

The comparative safety of oral versus intranasal desmopressin for the treatment of children with nocturnal enuresis

PURPOSE

Desmopressin is a well established and effective therapy for nocturnal enuresis. Water intoxication leading to hyponatremia is an infrequent but serious adverse event associated with desmopressin. We assessed the safety of desmopressin in children 18 years or younger with nocturnal enuresis with a focus on the relative safety of the oral compared with the intranasal formulation.

MATERIALS AND METHODS

Published data (MEDLINE) from December 1972 to August 2006 and post-marketing safety data from December 1972 to June 2005 were analyzed.

RESULTS

A total of 21 clinical trials on desmopressin use in children with nocturnal enuresis were identified. There were no reports of hyponatremia. A total of 21 publications were identified that included 48 case reports of hyponatremia in children with nocturnal enuresis. In all case reports patients were treated with intranasal desmopressin. Post-marketing safety data included 151 cases of hyponatremia in children with nocturnal enuresis, of whom 145 were treated with intranasal desmopressin and 6 were treated with the tablet formulation. Prodromal symptoms of hyponatremia were identified as headache, nausea and vomiting.

CONCLUSIONS

Data suggest that there is a decreased risk of hyponatremia with oral desmopressin compared with intranasal desmopressin. Identifiable and preventable risk factors for hyponatremia are inappropriately high fluid intake, administration of a larger than recommended dose, young age (less than 6 years) and concomitant administration of another medication. When desmopressin is prescribed, patients should be instructed to avoid high fluid intake when the medication is ingested, not ingest a higher than recommended dose and promptly discontinue the medication and seek assessment if headache, nausea or vomiting develops.

Neurologic disorders masquerading as pediatric sleep problems

Neurologic disorders may present or masquerade as pediatric sleep problems and fool the pediatrician, which may delay diagnosis and treatment. Many of the sleep problems in children with neurologic disorders arise directly from primary dysfunction or delayed maturation of their sleep-wake regulation systems. It is important to realize that nocturnal frontal lobe seizures or cluster headaches can be mistaken for night terrors, and craniopharyngiomas or myotonic dystrophy may present as narcolepsy-cataplexy. Hypothalamic dysfunction may explain not only the impaired circadian rhythm disorders in children with profound mental retardation but also excessive sleepiness and hyperphagia in Prader-Willi and Kleine-Levin syndromes. Intellectually challenged children perform better, learn more, and are better behaved with sufficient restorative sleep.