Hyponatremia caused by a reset osmostat in a neonate with cleft lip and palate and panhypopituitarism

Postoperative Dysnatremia in Pediatric Patients Undergoing Palatoplasty

OBJECTIVE

Identifying predisposing factors to dysnatremia to improve perioperative care after cleft surgery.

DESIGN

Retrospective case series. Patient data were obtained through the electronic medical records of the hospital.

SETTING

Tertiary care university hospital.

PATIENTS

The inclusion criterion was the measurement of an abnormal natremia value, defined as Na >150 or <130 mmol/l after a cleft lip or cleft palate repair procedure. The exclusion criterion was natremia between 131 and 149 mmol/l.

RESULTS

Natremia measurements were available for 215 patients born between 1995 and 2018. Five patients presented with postoperative dysnatremia. Several predisposing factors to dysnatremia have been identified: drugs, infection, administration of intravenous fluids, and postoperative syndrome of inappropriate antidiuretic hormone secretion. Although the hospital environment contributes to dysnatremia development, the fact that only patients undergoing cleft palate repair develop natremia anomalies suggests that this surgery may be itself a risk factor.

CONCLUSION

Children undergoing palatoplasty may be at higher risk to develop postoperative dysnatremia. Early recognition of symptoms and risk factors, postoperative monitoring, and prompt treatment of dysnatremia diminish the risk of neurological complications.

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.

Reset osmostat: a rare cause of hyponatraemia

Neonatal hyponatraemia is common, and related to significant morbidity and mortality. We report a case of a preterm newborn (gestational age of 36 weeks) with hyponatraemia, and with a prenatal diagnosis of cleft lip and palate, with a normal fetal karyotype. On the seventh day of life, a biochemical evaluation for jaundice and mild signs of dehydration showed hyponatraemia of 124 mmol/L. Investigation showed normal adrenal and thyroid functions, plasma hyposmolality (258 mOsm/kg); high urinary sodium (73 mmol/L) and high urinary osmolality (165 mOsm/kg). Despite oral sodium supplementation and fludrocortisone treatment, sodium levels remained between 124 and 130 mmol/L. Cranial ultrasound, brain MRI and renal ultrasound were normal. The diagnosis of hyponatraemia was unpredicted and the investigation was suggestive of reset osmostat, a subtype of the syndrome of inappropriate secretion of antidiuretic hormone, characterised by a subnormal threshold for antidiuretic hormone secretion.

Oral urea for the treatment of chronic syndrome of inappropriate antidiuresis in children

We report the successful use of oral urea in the management of children with chronic syndrome of inappropriate antidiuretic hormone secretion (SIAD). We performed a retrospective review of four children with chronic SIAD. After initial attempts at management with fluid restriction, each was started on a 30% to 50% oral urea solution, and the dose was titrated until normal serum sodium was achieved. Fluid intake was liberalized after serum sodium normalization. All four children normalized their serum sodium. No side effects or toxicities were experienced. Oral urea is a safe, effective treatment for chronic SIAD in children.

Hyponatremia secondary to reset osmostat in a child with a central nervous system midline defect and a chromosomal abnormality

A newborn with a CNS midline defect and persistent hyponatremia was diagnosed with a "reset" osmostat using a 3% hypertonic saline test. The diagnosis was established by measuring urinary arginine vasopressin (UAVP) and plasma osmolality (P(Osmoil)). In this infant a chromosome abnormality with the karyotype 46, X, -X, +der(X) t(X;13) (p22.1;q22) was associated with the midline defect and a reset osmostat.

Vasopressin and thirst in patients with posterior pituitary ectopia and hypopituitarism

OBJECTIVE

Partial diabetes insipidus has been documented in patients with congenital hypopituitarism and posterior pituitary ectopia, some cases being clinically silent except for enuresis. The objective of our study was to evaluate vasopressin (AVP) secretion and thirst appreciation in hypopituitary patients with posterior pituitary ectopia.

PATIENTS

Twelve males and three females, aged between 13 and 38 years (median 19 years). Eleven had multiple pituitary deficiencies, adequately replaced at the time of the study, and four were only growth hormone deficient. None of the patients suffered from polyuria, polydipsia or nocturnal enuresis. We tested the patients with a 5% NaCl infusion. Five patients with abnormal vasopressin production were also tested with nitroprusside, which affects baroceptor vasopressin secretion.

RESULTS

We found that only two out of 12 patients had normal AVP secretion. Thirst assessment showed severe hypodipsia in one patient, hyperdipsia in three out of 15 and more subtle abnormalities in two out of 15 patients. Concordance was found between osmotically and baroceptor-stimulated vasopressin.

CONCLUSIONS

Patients with posterior pituitary ectopia showed a high prevalence of subclinical subnormal vasopressin response to the osmolar stimulus and moreover an impairment of thirst appreciation. Our data on nonosmotically stimulated AVP release suggest the existence of a damage in the hypothalamic vasopressin secreting centres.