Hypernatremia

Serum osmolality and hyperosmolar states

Serum osmolality is the sum of the osmolalities of every single dissolved particle in the blood such as sodium and associated anions, potassium, glucose, and urea. Under normal conditions, serum sodium concentration is the major determinant of serum osmolality. Effective blood osmolality, so-called blood tonicity, is created by the endogenous (e.g., sodium and glucose) and exogenous (e.g., mannitol) solutes that are capable of creating an osmotic gradient across the membranes. In case of change in effective blood osmolality, water shifts from the compartment with low osmolality into the compartment with high osmolarity in order to restore serum osmolality. The difference between measured osmolality and calculated osmolarity forms the osmolal gap. An increase in serum osmolal gap can stem from the presence of solutes that are not included in the osmolarity calculation, such as hypertonic treatments or toxic alcoholic ingestions. In clinical practice, determination of serum osmolality and osmolal gap is important in the diagnosis of disorders related to sodium, glucose and water balance, kidney diseases, and small molecule poisonings. As blood hypertonicity exerts its main effects on the brain cells, neurologic symptoms varying from mild neurologic signs and symptoms to life-threatening outcomes such as convulsions or even death may occur. Therefore, hypertonic states should be promptly diagnosed and cautiously managed. In this review, the causes and treatment strategies of hyperosmolar conditions including hypernatremia, diabetic ketoacidosis, hyperglycemic hyperosmolar syndrome, hypertonic treatments, or intoxications are discussed in detail to increase awareness of this important topic with significant clinical consequences.

Diagnosis and management of hypernatraemia in children

Hypernatraemia is most commonly caused by excessive loss of solute-free water or decreased fluid intake; less often, the aetiology is salt intoxication. Especially infants, young children and individuals with a lack of access to water are at risk of developing hypernatraemia. Diagnosis is based on detailed history, physical examination and basic laboratory tests. Correction of hypernatraemia must be slow to prevent cerebral oedema and irreversible brain damage. This article reviews the aetiology, differential diagnosis and management of conditions associated with paediatric hypernatraemia. Distinguishing states with water deficiency from states with salt excess is important for proper management of hypernatraemic patients.

Term Infant with Cerebral Venous Sinus Thrombosis

Hypernatremic dehydration in neonates is a common condition in an exclusively breastfed infant but often underdiagnosed. Any newborn who has lost more than 10% of birthweight should be carefully evaluated and monitored for clinical features of dehydration. Efforts such as frequent follow-up for weight check, and formula supplementation, if needed, should be provided to a neonate at risk of developing complications of dehydration. Adequate lactation consultation, both inpatient and outpatient, should also be provided, especially to the primigravida mother. Here, we present a case of a neonate with severe hypernatremic dehydration caused by inadequate lactation in a primigravida mother, which resulted in cerebral venous sinus thrombosis leading to significant intracerebral hemorrhage. The infant suffered permanent neurologic damage and was sent home on technological devices (tracheostomy and gastrostomy tubes). Further, we provide a brief review of hypernatremic dehydration and sinus venous thrombosis in neonates.

Neonatal Hypernatremic Dehydration

Hypernatremic dehydration in exclusively breast-fed neonates is associated with a free water deficit secondary to inadequate fluid intake. It is a common but underrecognized problem in the primary care setting, as the degree of dehydration can be underestimated due to fluid shifts. Neonates of primiparous mothers and those who experience greater weight loss in the first week of life are at higher risk of developing hypernatremic dehydration and most often present for care between 6 and 10 days of life. No consensus treatment guidelines exist, but most experts recommend a goal reduction rate of serum sodium levels of 0.5 mEq/L per hour with correction over 48 hours. Serum sodium level greater than 160 mEq/L is a risk factor for morbidity and mortality. Complications of hypernatremic dehydration, with seizure being most common, usually occur during improper correction. Several small studies have documented varying degrees of neurodevelopmental delay on long-term follow-up of patients admitted for hypernatremic dehydration treatment as a neonate. [Pediatr Ann. 2019;48(5):e197-e200.].

Bloody Stools in a 3-Day-Old Term Infant

A 3-day-old term, male infant presented to the emergency department for evaluation of bloody stools. The infant was born after an uncomplicated pregnancy followed by a normal spontaneous vaginal delivery. The mother was group B Streptococcus colonized, and received antenatal penicillin prophylaxis. The infant received routine delivery room care, and was given ophthalmic erythromycin and intramuscular vitamin K. Circumcision was performed without bleeding and he was discharged from the newborn nursery and the hospital after 48 hours. On the day of presentation, he had streaky bright red blood in 4 consecutive stools. After discussion with the infant's pediatrician, the parents took him to the emergency department. The infant was afebrile, nursing well without emesis, and had made ∼10 wet diapers that day. The physical examination revealed a fussy infant with mild tachycardia, tachypnea, and scleral icterus. The complete blood count was unremarkable. Serum total bilirubin was 11.9 mg/dL, sodium 156 mmol/L, chloride 120 mmol/L, potassium 4.7 mmol/L, and bicarbonate 16 mmol/L. International normalized ratio was prolonged at 2.7, prothrombin time 26.6 seconds, partial thromboplastin time 38.9 seconds. The stool was hemeoccult positive. An obstructive radiograph series of the abdomen showed a nonobstructed gas pattern. Official radiology interpretation the following day reported possible pneumatosis intestinalis in the left and right colon. Our multidisciplinary panel will discuss the assessment of bloody stools in the term newborn, evaluation of electrolyte abnormalities, the diagnosis, and patient management.

Optimizing operational efficiencies in early phase trials: The Pediatric Trials Network experience

Performing drug trials in pediatrics is challenging. In support of the Best Pharmaceuticals for Children Act, the Eunice Kennedy Shriver National Institute of Child Health and Human Development funded the formation of the Pediatric Trials Network (PTN) in 2010. Since its inception, the PTN has developed strategies to increase both efficiency and safety of pediatric drug trials. Through use of innovative techniques such as sparse and scavenged blood sampling as well as opportunistic study design, participation in trials has grown. The PTN has also strived to improve consistency of adverse event reporting in neonatal drug trials through the development of a standardized adverse event table. We review how the PTN is optimizing operational efficiencies in pediatric drug trials to increase the safety of drugs in children.

What is the safe approach for neonatal hypernatremic dehydration? A retrospective study from a neonatal intensive care unit

OBJECTIVES

The aims of this study were to evaluate the prevalence, complications, and mortality of hypernatremic dehydration in neonates and to compare the effect of correction rate at 48 hours on mortality and on neurological outcome in the short term.

METHODS

This retrospective study was conducted between January 2007 and 2011 in the neonatal intensive care unit. Term neonates were included. The patients were grouped as follows: group 1 = 150 to 160 mmol/L, group 2 = 161 to 170 mmol/L and group 3 = 171 to 189 mmol/L.

RESULTS

Among 4280 neonates, 81 cases (1.8%) had hypernatremic dehydration. Groups 1, 2, and 3 consisted of 55, 23, and 3 patients, respectively. Mortality rates were as follows: 3.6%, 17.3%, and 66.6%. Mean serum sodium (Na) correction rates at 0 to 24 hours and 24 to 48 hours were 0.48 ± 0.2 versus 0.38 ± 0.31 mmol/L per hour (group 1) and 0.49 ± 0.21 versus 0.52 ± 0.28 mmol/L per hour (group 2), respectively. In 32 patients (58.1%) from group 1 and in 13 patients (56.5%) from group 2, correction rate of 0.5 mmol/L per hour or less was achieved. Twenty-two patients developed convulsions, which was the most common complication during therapy. Serum Na greater than 160 mmol/L at admission (odds ratio, 1.9; 95% confidence interval, 1.3-3.7) and serum Na correction rate of greater than 0.5 mmol/L per hour (odds ratio, 4.3; 95% confidence interval, 1.2-6.5) were independent risk factors for death or convulsion. There was a significant difference between groups 1 and 2 in Denver Developmental Screening Test II results (64.1% vs 30.7 %, P = 0.001).

CONCLUSION

Hypernatremic dehydration is an important problem that should be managed properly to avoid adverse outcomes.

Normal saline is a safe initial rehydration fluid in children with diarrhea-related hypernatremia

To demonstrate safety and efficacy of using normal saline (NS) for initial volume expansion (IVE) and rehydration in children with diarrhea-related hypernatremic dehydration (DR-HD), forty eight patients with DR-HD were retrospectively studied. NS was used as needed for IVE and for initial rehydration. Fluid deficit was given over 48 h. Median Na(+) level on admission was 162.9 mEq/L (IQR 160.8-165.8). The median average hourly drop at 6 and 24 h was 0.53 mEq/L/h (0.48-0.59) and 0.52 mEq/L/h (0.47-0.57), respectively. Compared to children not needing IVE, receiving ≥40 ml/kg IVE was associated with a higher average hourly drop of Na(+) at 6 h (0.51 vs. 0.58 mEq/L/h, p = 0.013) but not at 24 h (p = 0.663). The three patients (6.3%) with seizures had a higher average hourly drop of Na(+) at 6 and 24 h (p = 0.084 and 0.021, respectively). Mortality (4/48, 8.3%) was not related to Na(+) on admission or to its average hourly drop at 6 or 24 h. Children receiving ≥40 ml/kg IVE were more likely to die (OR 3.3; CI, 1.5-7.2).

CONCLUSION

In children with DR-HD, NS is a safe rehydration fluid with a satisfactory rate of Na(+) drop and relatively low incidence of morbidity and mortality. Judicious use of IVE should be exerted and closer monitoring should be guaranteed for children requiring large volumes for IVE and for those showing rapid initial drop of serum Na(+) to avoid neurological complications and poor outcome.