ELECTRONIC ARTICLE |


* Division of Nephrology
Emergency Medicine
General Academic Pediatrics, Department of Pediatrics, Children's Hospital Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
|| Division of Nephrology, Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| ABSTRACT |
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Study Design. A retrospective study was conducted at Children's Hospital of Pittsburgh over a 5-year period, to identify otherwise healthy term and near-term (
35 weeks of gestation) breastfed neonates (<29 days of age) who were admitted with serum sodium concentrations of
150 mEq/L and no explanation for hypernatremia other than inadequate milk intake.
Results. The incidence of breastfeeding-associated hypernatremic dehydration among 3718 consecutive term and near-term hospitalized neonates was 1.9%, occurring for 70 infants. These infants were born primarily to primiparous women (87%) who were discharged within 48 hours after birth (90%). The most common presenting symptom was jaundice (81%). Sixty-three percent of infants underwent sepsis evaluations with lumbar puncture. No infants had bacteremia or meningitis. Infants had hypernatremia of moderate severity (median: 153 mEq/L; range: 150177 mEq/L), with a mean weight loss of 13.7%. Nonmetabolic complications occurred for 17% of infants, with the most common being apnea and/or bradycardia. There were no deaths.
Conclusion. Hypernatremic dehydration requiring hospitalization is common among breastfed neonates. Increased efforts are required to establish successful breastfeeding.
Key Words: breastfeeding hypernatremia dehydration jaundice neonate
Abbreviations: ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification MWH, Magee-Womens Hospital
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 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, 6 We refer to this as "breastfeeding-associated hypernatremia," with the clear understanding that this results only when breastfeeding is not properly established. Hypernatremic dehydration is assumed to be a rare complication of breastfeeding,7 but recent reports have suggested that the incidence is increasing.811 The failure to diagnose hypernatremic dehydration can have serious consequences, including seizures, intracranial hemorrhage,12 vascular thrombosis,13 and death.14, 15 The purpose of this study was to assess the incidence and complications of breastfeeding-associated hypernatremia among hospitalized neonates at a large pediatric tertiary care center in the United States.
| METHODS |
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12000 admissions per year. After approval was obtained from the institutional review board, a retrospective study was conducted to identify otherwise healthy term and near-term (gestation of
35 weeks) neonates admitted during a 5-year period with serum sodium concentrations of
150 mEq/L. A total of 3718 term and near-term infants <29 days of age were discharged from Children's Hospital of Pittsburgh between January 1997 and December 2001; 406 preterm infants were excluded from review with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) discharge diagnosis codes indicating prematurity (codes 765.00765.19). The charts of neonates with the following ICD-9-CM discharge diagnosis codes were reviewed: hyperosmolality (code 276.0; n = 22), neonatal dehydration (code 775.5; n = 247), fetal/neonatal jaundice (code 774.6; n = 598), or newborn feeding problems (code 779.3; n = 202). Some children had >1 of the ICD-9-CM codes. Patients were excluded if an explanation for hypernatremia other than inadequate milk intake could be identified, such as an acute or chronic illness that could affect feeding. Seventy singleton infants fulfilled the study criteria, all of whom were breastfed and 16 (23%) of whom were near term (3537 weeks of gestation). No formula-fed infants fulfilled the study inclusion criteria.
For demographic purposes, the study group was compared with a historical control group composed of 21158 infants (
35 weeks of gestation) who were born at Magee-Womens Hospital (MWH) in Pittsburgh between 1999 and 2001. MWH is representative of the catchment area, accounting for 83% of live births in Allegheny County. The control group data were obtained from the Magee Obstetrics, Maternal, and Infant database, which is an ongoing data collection project at MWH. The database includes data on all women who deliver at MWH and their infants and is an electronic version of a structured, closed-format, medical record abstraction.
Data were reported as the mean ± SD or median (range) as appropriate. Ordinal data were analyzed with the Mann-Whitney rank-sum test, unpaired t test, or comparison of overlapping and nonoverlapping confidence intervals, as appropriate. Nominal data were analyzed with the
2 test. Correlations were determined with the Spearman rank correlation coefficient. P values of <.05 were considered significant.
| RESULTS |
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150 mEq/L (Table 1). Compared with historical control data, maternal and infant characteristics were similar with respect to maternal age, gestational age, gender, and delivery method. Hypernatremic infants were significantly more likely to be born to primiparous mothers than were infants in the control group (87% vs 43%; P < .001). Hypernatremic infants had lower birth weights than control subjects (Table 1) but similar birth weights in comparison with primiparous control infants (3245 g [95% confidence interval: 31463362 g] vs 3345 g [95% confidence interval: 33363355 g]). Ninety percent of mothers (60 of 66 mothers) were discharged with their infants within 48 hours after birth; discharge data were not available for 4 infants. Five of the 9 multiparous mothers had had difficulty breastfeeding previous children. Of these, 1 mother had an infant from a previous pregnancy admitted with dehydration resulting from insufficient lactation. Seasonal occurrence was not a risk factor.
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| DISCUSSION |
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In the present study, the 5-year incidence of breastfeeding-associated hypernatremia among all hospitalized term and near-term neonates was 1.9% (70 cases per 3718 admissions), significantly higher than the reported incidence of hypernatremia attributable to all causes among hospitalized children, adults, and elderly subjects (1.1%).7, 17, 18 The incidence of breastfeeding-associated hypernatremia requiring readmission would be 21 cases per 10000 live births for infants at
35 weeks of gestation (44 cases per 21158 births from 1999 to 2001), assuming that the catchment area for Children's Hospital of Pittsburgh is similar to that of MWH. The incidence for breastfed newborns would be 47 cases per 10000 live births, assuming a breastfeeding initiation rate of 44%.19 Our data are consistent with those of others who have noted a high incidence of breastfeeding-associated hypernatremia.8, 10, 20
There is reason to think that the incidence of breastfeeding-associated hypernatremia will increase and that currently the condition is under-recognized. The number of women who initiate breastfeeding will likely increase, because the American Academy of Pediatrics advocates strongly that nearly every infant should be breastfed21 and the Surgeon General has set a goal of 75% of mothers initiating breastfeeding by 2010.22 Findings from a recent study revealed that 16% of exclusively breastfed infants born to primiparous women had >10% weight loss by day 3 of life, despite education and support provided by a lactation consultant.23 It is estimated that 10% of breastfed infants develop hypernatremia24 and that
33% of breastfed infants with weight loss exceeding 10% have hypernatremia.9, 10 This suggests that breastfeeding-associated hypernatremia is much more common than thought previously, with a higher rate than reported in our study.
Breastfeeding-associated hypernatremia can be difficult to recognize clinically. Most infants in our study presented with either jaundice or symptoms consistent with sepsis, such as fever and lethargy. Most of these patients were admitted for presumed sepsis and underwent a full sepsis evaluation, including lumbar puncture and treatment with antibiotics. Although 73% of infants had >10% weight loss, dehydration was noted rarely in the medical records before laboratory evaluation. This is not surprising, because infants with hypernatremic dehydration have better-preserved extracellular volume and therefore have less-pronounced clinical signs of dehydration.25 However, weight loss and inadequate stooling are sensitive indicators of dehydration among breastfed infants and should be included in the history of all infants presenting for evaluation of jaundice, fever, weight loss, and lethargy.8
Many breastfed infants with hypernatremic dehydration in this study had short-term complications. Because of the retrospective nature of this study, long-term follow-up data were not evaluated. There is good reason to think that breastfeeding-associated hypernatremia can have serious deleterious consequences. Recent prospective data revealed that more than one half of infants admitted with breastfeeding-associated hypernatremia exhibited abnormal development with long-term follow-up monitoring.26 This is consistent with previous data that revealed long-term neurologic sequelae among children with hypernatremia.27 Hypernatremic dehydration among infants has been associated historically with high mortality rates.2831 Serious vascular complications and death were reported in previous studies of breastfeeding-associated hypernatremia8, 14 and in a our institution.32 The number of central nervous system complications in this study was likely underestimated, because only 4 patients underwent neuroimaging studies.
The association of hypernatremia with severe hyperbilirubinemia (bilirubin concentrations of >25 mg/dL), which occurred for 20% of our patients, might contribute to long-term neurologic sequelae. Hypernatremia can cause disruption in the blood-brain barrier, which facilitates the diffusion of bilirubin across the blood-brain barrier and thereby may enhance the risk of bilirubin encephalopathy.33 Hypernatremia and hyperbilirubinemia each cause central nervous system depression among infants with lethargy, poor suck, and anorexia.34, 35 These factors can lead to a cycle of worsening dehydration, jaundice, and hypernatremia, which in combination can lead to brain injury.
Because of the retrospective nature of this study, there were some variables that we were unable to assess. First, this study probably underestimated the true incidence of breastfeeding-associated hypernatremia, because we queried charts only on the basis of ICD-9-CM codes and not on the basis of serum sodium concentrations. Serum sodium levels were not determined for all breastfed infants requiring readmission. Second, because of the incomplete nature of the feeding histories recorded in the medical records, we were unable to assess the possible reasons for lactation failure, such as inadequate latch, poor breastfeeding technique, low milk supply, inadequate feeding frequency, or maternal illness. The failure of physicians to record adequate feeding and elimination histories suggests the need for better physician training in breastfeeding management. We were not able to assess the adequacy of follow-up monitoring and breastfeeding education and support that were provided. Third, given the nature of the study design, there were important maternal characteristics that we were unable to assess, such as maternal education, socioeconomic status, marital status, and social support.
It is unclear why the incidence of breastfeeding-associated hypernatremia may be increasing, but it does not seem to be attributable to early discharge from the hospital or to a higher incidence of breastfeeding. Studies indicated that early discharge was not associated with increased readmission rates.36, 37 The breastfeeding initiation rate in Western Pennsylvania is among the lowest in the nation at only 44%.19 The high incidence of breastfeeding-associated hypernatremia among infants born to first-time mothers may be related to the fact that primiparous women produce significantly less milk than multiparous women during the first postpartum week, with a subset of primiparous women having very low milk production during the first postpartum week.38 The increasing incidence of hypernatremia could also be attributable to less-stringent criteria for treating neonatal hyperbilirubinemia.16 Less-stringent guidelines for the treatment of neonatal jaundice would result predictably in a later presentation of insufficient lactation. Jaundice is a common clinical sign of insufficient lactation.39 Perhaps measurement of serum sodium concentrations should be added to the practice guidelines for the management of hyperbilirubinemia.40
Breastfeeding-associated hypernatremia should be completely preventable. Unfortunately, physicians receive limited residency training to deal with breastfeeding complications, and there is general reluctance to provide supplemental formula to breastfed infants with insufficient lactation.41 Most pediatric texts do not give clear recommendations regarding how to treat breastfed infants with excessive weight loss or when to intervene with supplemental feeding.42 Obviously, the goal is to prevent dehydration, which must begin with adequate breastfeeding assistance in the newborn nursery that continues after discharge. To this end, breastfed infants should be evaluated by an experienced health care professional at no more than 3 to 5 days of age, as recommended in the most recent American Academy of Pediatrics guidelines.21 Infants should be evaluated with a weight check, physical assessment of hydration and jaundice, and evaluation of breastfeeding and infant elimination patterns. Most breastfeeding-associated hypernatremia could be prevented if infants with excessive weight loss or inadequate breast milk transfer were judiciously given expressed breast milk if available and formula if necessary until breast milk production increased and breastfeeding difficulties were addressed by a health care provider well trained in lactation support.
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Address correspondence to Michael L. Moritz, MD, Division of Nephrology, Children's Hospital of Pittsburgh, 3705 Fifth Ave, Pittsburgh, PA, 15213-2538. E-mail: michael.moritz{at}chp.edu
No conflict of interest declared.
| REFERENCES |
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T Ozdogan, M Iscan, C Ellikcioglu, and E Yildiz Hypernatraemic dehydration in breast-fed neonates. Arch. Dis. Child., December 1, 2006; 91(12): 1041 - 1041. [Full Text] [PDF] |
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K. A. Bonuck, K. Freeman, and M. Trombley Randomized controlled trial of a prenatal and postnatal lactation consultant intervention on infant health care use. Arch Pediatr Adolesc Med, September 1, 2006; 160(9): 953 - 960. [Abstract] [Full Text] [PDF] |
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A McKie, D Young, and P D MacDonald Does monitoring newborn weight discourage breast feeding? Arch. Dis. Child., January 1, 2006; 91(1): 44 - 46. [Abstract] [Full Text] [PDF] |
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Minerva BMJ, December 17, 2005; 331(7530): E398 - E398. [Full Text] [PDF] |
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Minerva BMJ, September 24, 2005; 331(7518): 704 - 704. [Full Text] [PDF] |
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