Moderate Hypernatremic Dehydration in Newborn Infants: Retrospective Evaluation of 64 Cases

Written By: Sam Savage

Published Date: July 4, 2007 Last Edited: July 4, 2007

By Uras, Nurdan Karadag, Ahmet; Dogan, Guzide; Tonbul, Alparslan; Tatli, M Mansur

Abstract Objectives. This study was carried out to assess the incidence, presenting complaints, risk factors, and methods for prevention of hypematremic dehydration among term and near-term breastfeeding infants.

Methods. We retrospectively evaluated term and near-term (>/=35 weeks of gestation) neonates admitted to our neonatology department, during a four-year period with serum sodium concentrations of >/= 146 mEq/L. A detailed maternal and infant history and examination including presenting complaints, risk factors, feeding problems, and weight loss, if present, were registered.

Results. Among 1150 neonates admitted to our unit, 64 (5.6%) had serum sodium concentrations of > 145 mEq/L, in whom 43 of them had sodium concentrations of > 149 mEq/L. The most common presenting complaint was jaundice in 30 patients (48%). Forty-one (95%) of the 43 patients described a more than 7% weight loss and there was a positive correlation between serum sodium and urea and creatinine concentrations, and a negative correlation between serum sodium and glucose concentrations in these patients (p 149 mEq/L and 0.05).

Conclusions. Weight loss in an infant of greater than 7% from birth weight increases the risk of hypernatremia, a weight loss limit that is lower than the previously reported 10%. This indicates possible breastfeeding problems and requires more intensive evaluation of breastfeeding and possible interventions to correct problems and improve milk production and transfer.

Keywords: Newborn, hypematremic dehydration, breastfeeding

Introduction

The benefits of breastfeeding to children are well established and include decreased incidence of a wide variety of acute infections and chronic diseases, as well as improved neurodevelopmental outcomes [1,2]. A serious potential complication of insufficient breastfeeding is severe hypernatremic dehydration [3]. Despite the well-recognized advantages of breastfeeding to both mother and infant, hypernatremic dehydration may occur in the first week of life. Neonatal hypernatremic dehydration results from inadequate transfer of breast milk from mother to infant. Furthermore, poor milk drainage from the breasts results in persistence of high milk sodium concentrations [4]. This may exacerbate neonatal hypernatremia [5]. In the last few years the number of anecdotal reports of hypernatremic dehydration in breastfed infants has increased [6,7]. Moreover, recent retrospective studies indicate an increase in the frequency and severity of this problem; however, its real incidence is not known [8].

The aim of this study was to assess the incidence, presenting complaints and risk factors for hypernatremic dehydration, and the methods of preventing this problem among breastfeeding infants.

Methods

We retrospectively evaluated term neonates admitted between 1 January 2002 and 31 December 2005 to the Neonatal Department of Fatih University Faculty of Medicine with a serum sodium > 145 mEq/ L. Enrollment criteria included neonates younger than 29 days of age with a gestational age of more than 35 weeks who were exclusively breastfed, with normal neonatal adaptation. Exclusion criteria were having a congenital malformation, cerebral injury, prolonged fever, salicylate toxicity, hyperventilation, diabetes insipidus, and excessive salt intake. Detailed maternal and infant history and examination including maternal age, parity, length of pregnancy, breastfeeding history, level of education, modality of delivery, hospital stay, presenting complaints, risk factors, feeding problems, and weight loss, if present, were registered. The serum sodium, urea, bilirubin, and glucose concentrations of the neonate were also recorded. The patients were divided into two groups according to their serum sodium level. Group 1 consisted of patients with serum sodium 149 mEq/L. The patients in groups 1 and 2 were also grouped according to degree of weight loss (=7% or > 7%) from birth weight. Risk factors in both groups were determined.

Statistical analysis

SPSS 11.5 for Windows was used for statistical analysis. Chi- square, Student’s r-test, and Fisher’s exact test were used, with the level of significance set at p

Results

Our unit is a tertiary care center that accepts approximately 300 admissions per year. Between January 2002 and December 2005, 1150 neonates were admitted to our unit; 64 (5.6%) of these had a serum sodium concentration of more than 145 mEq/ L. Demographic data are presented in Table I.

Signs and symptoms on presentation to the hospital are summarized in Table II. The most common presenting symptom was jaundice (41%). In patients presenting with poor oral intake, no clinical or laboratory evidence of infection was present. Presenting signs included jaundice in 30 of the patients (48%), poor oral intake in 20 (31%), fever in 23 (36%), low urine output in three (5%), and lethargy in three (5%) of the patients.

Table I also presents clinical and laboratory data. Forty-three of 64 patients had a serum sodium concentration of > 149 mEq/L (range 150-168 mEq/L). Characteristics of newborns with serum sodium =149 mEq/L (group 1) and with serum sodium > 149 mEq/L (group 2) are presented in Table III. Mean age at admission of group 1 was 3.4 +-1.8 days and of group 2 was 3.5+1.3 days (p > 0.05). Fifteen of 43 patients in group 2 were born vaginally (35%) while 28 were born by cesarean section (65%). No significant relationship was found between the delivery method and hypernatremia. There was a positive correlation between serum sodium concentration and weight loss, serum urea and creatinine concentrations. Hypoglycemia was observed in none of the hypernatremic patients. The patients were also grouped according to weight loss: >7% or =7%. There was no significant difference between symptoms and signs in these groups (p > 0.05). Forty-one of the patients in group 2 (95%) described weight loss of more than 7% (820%). These patients showed a significant relationship with serum sodium, urea and creatinine concentrations (p

Table I. Demographic, clinical and laboratory data of hypematremic neonates (N = 64).

Table II. Presenting signs of hypernatremic neonates (N = 64).

When seasonal occurrence was analyzed, although hypernatremia and weight loss >/=7% were more frequently observed in summer, this was not statistically significant (p = 0.05).

A significant relationship was found between serum bilirubin levels and epidural anesthesia in group 2 (p

Table III. Group 1 and group 2 characteristics.

Discussion

Hypernatremia may be associated with a deficiency in breast milk intake, excessive fluid loss, or excessive sodium intake. Adequate breast milk intake depends on several interrelated stages: normal mammary development (mammogenesis), unimpeded initiation of lactation (lactogenesis), sustained ongoing milk synthesis (galactopoesis), and effective milk removal. Milk removal depends on effective maternal and infant breastfeeding techniques, combined with an intact milk-ejection reflex, and total daily milk intake depends on frequency and duration of feeds and the pattern of breast use [9].

The incidence of hypernatremic dehydration is difficult to ascertain. There are limited studies about hypernatremic dehydration in the neonatal period. Oddie et al. [10] have reported an incidence of 2.5 hypernatremic dehydrations per 10 000 live births. Manganaro et al. [8] found that of 686 neonates referred over a six-month period, 53 of them had a weight loss of > 10% and 19 had a plasma sodium concentration > 149 mmol/L. Michael et al. [5] found that the five-year incidence of breastfeedingassociated hypernatremia among all hospitalized term and near-term neonates was 1.9%. In our study the incidence of hypernatremia with a serum sodium concentration > 145 mEq/L was 5.6% and > 149 mEq/L was 3.7%.

The last policy statement of the American Academy of Pediatrics about breastfeeding and the use of human milk have reported that weight loss in the infant of greater than 7% from birth weight should indicate possible feeding problems and should require more intensive evaluation of breastfeeding [U]. This was the first study that underlies the importance of weight loss greater than 7% in newborns because we found that weight loss greater than 7% was related to higher sodium, urea and creatinine concentrations. According to American Academy of Pediatrics reports, all breastfeeding newborn infants should be evaluated by a pediatrician at 3-5 days of age. In our study, our patients were also examined on the 4th and 5th days. Although they were asymptomatic, hypernatremia was found in nine (14%) of them. This indicates the importance of more intensive evaluation of breastfeeding and weight loss on the 3rd-5th day controls.

As intracellular fluid passes to the extracellular space in hypernatremia, clinical signs of dehydration are usually masked. Clinical findings can be observed in the presence of severe dehydration. As the enterohepatic circulation increases with dehydration, serum bilirubin levels increase [12,13]. The most common complaint in our patients was also jaundice, and half of our patients presented with this symptom. In our study there was no correlation between bilirubin levels and peak serum sodium concentrations. But epidural anesthesia was correlated with serum bilirubin concentrations. There was also a negative correlation between serum bilirubin levels and hospital stay. Neonates who were born with epidural anesthesia and with shorter hospital stays had higher bilirubin levels than the ones born with general anesthesia. These results demonstrated the higher bilirubin levels in neonates with early discharge, as mothers with vaginal delivery and epidural anesthesia stay shorter than the ones with general anesthesia (12- 24 hours vs. 48-72 hours). Manganaro et al. [8] have reported that cesarean delivery and lower maternal education were risk factors for hypernatremic dehydration in neonates. They also demonstrated that a weight loss >10% during the first days of life was an easy and effective method for early identification of dehydration before serious hypernatremia occurred. Erdeve et al. [14] reported cesarean section as a risk factor for hypernatremic dehydration in breastfed infants. Michael et al. [5] found that hypernatremic infants were significantly more likely to be born to primiparous mothers than were infants in the control group. However, in our experience 89% of neonates with a weight loss > 7% had hypernatremia. In addition, we found that neonatal weight monitoring was an adequate parameter showing poor breastfeeding technique. Our observation points to the fact that the commonly used 10% limits of weight loss should be lowered. Also no significant difference was observed in delivery type, parity, maternal education, hospital stay, and anesthesia type between groups 1 and 2. Although hypernatremia and weight loss greater than 7% from birth weight were more common in summer this was not significant.

In conclusion, weight loss in the infant of greater than 7% from birth weight increases the risk of hypernatremia. Although results of our study about birth weight loss being a risk factor for hypernatremia are in concordance with previous results, the weight loss percentage associated with hypernatremia in this study is lower than previously reported limits (7% vs. 10%). Doctors should be aware that weight loss in neonates of less than 10% may also be harmful. Further studies are warranted to evaluate the risk level in larger populations.

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NURDAN URAS, AHMET KARADAG5 GUZIDE DOGAN5 ALPARSLAN TONBUL5 & M. MANSUR TATLI

Department of Pediatrics and Neonatology, Fatih University Faculty of Medicine, Ankara, Turkey

(Received 10 July 2006; revised 18 September 2006; accepted 6 February 2007)

Correspondence: Nurdan Uras, MD, Department of Pediatrics and Neonatology, Fatih University Faculty of Medicine, Hosdere Cad. No. 145, Y. Ayranci, Cankaya 06540, Ankara, Turkey. Tel: +90 312 440 06 06. Fax: +90 312 441 54 98. E-mail: [email protected]

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