Hypernatremic Dehydration in Breastfed Term Infants: Retrospective Evaluation of 159 Cases

Abstract

Objectives:

The aim of this study was to reveal the frequency, presenting complaints, risk factors, complications, and ways for prevention of hypernatremic dehydration (HD) among term breastfed infants.

Methods:

The files of 159 breastfed term infants hospitalized because of HD between the years 2009 and 2014 were examined retrospectively in the Neonatal Intensive Care Unit of Sivas State Hospital, Turkey. The patients were classified according to serum sodium (Na) levels, group 1 (Na: 146–149 mEq/L, n = 68) and group 2 (Na ≥150 mEq/L, n = 91).

Results:

The most common complaint was fever (67.9%), and the most common physical finding was oral mucosal dryness (76%). There were positive correlations between serum Na levels and weight loss, hospital stay, admission age, admission to neonatal unit after discharge, serum urea levels, and body temperature (p < 0.05). The normalization period of Na levels was significantly longer (21.7 ± 8.8 versus 29.3 ± 17.8 hours, p = 0.03), and Na reduction rate was faster in group 2 (0.41 ± 0.3 versus 0.50 ± 0.3 mEq/L/hour, p = 0.02). Bradycardia was seen more commonly in group 2 (1.5% versus 16.5%, p = 0.002).

Conclusions:

HD is a significant condition that should be treated appropriately to avoid serious complications.

Introduction

Breast milk is a unique nutrient for the development and growth of the infant.¹ It has been proven to protect the infant from many diseases that can develop in infancy and upcoming years of life. The World Health Organization recommends that all infants should only be breastfed for the first 6 months, and breastfeeding should be maintained until the age of 2 along with the complementary foods.²

Many programs focusing on supporting breastfeeding are applied throughout the world to increase the number of breastfeeding mothers.³ Despite these remarkable and supportive approaches emphasizing on breast milk, insufficient breast milk and the risks caused by this condition for the infant should not be ignored.⁴ If breastfeeding is not as targeted and sufficient, a dramatic weight loss and dehydration along with an increase in serum sodium (Na) concentration related to the insufficient breast milk intake may be observed mostly on the first days of the infant.⁵ Nutritional problems and hypernatremic dehydration (HD) are the most common causes of newborn hospitalization in developing countries.⁶

If HD is not diagnosed early and treated suitably, it may lead to serious problems. Its complications include indirect hyperbilirubinemia, prerenal azotemia, renal failure, increasing of liver enzymes, disseminated intravascular coagulation, intracranial hemorrhage, thrombosis, convulsion, cerebral edema, and even death.^7–11

The purpose of this study is to assess the HD frequency among hospitalized neonates at the Neonatal Intensive Care Unit (NICU) of Sivas State Hospital (SSH) and also to introduce complaints at admission, risk factors of HD, and the ways of protection from this condition. Another purpose is to find out if there is any difference in terms of clinical findings, treatment process, and developing complications in between neonates with mild HD (Na: 146–149 mEq/L)^12–14 and severe HD (Na ≥150 mEq/L)^12–14

Methods

The files of term newborns hospitalized with diagnosis of HD at NICU of SSH in Turkey between September 2009 and September 2014 were retrospectively examined. The infants whose serum Na ≥146 mEq/L^5,13–17 and those only breastfed were included; newborns who were born before 37th gestational age, were older than 28 days, and who had congenital anomaly, metabolic/endocrine diseases, asphyxia, sepsis, intrauterine infections, and neurological diseases were excluded in this study.

Demographic data, such as maternal age, parity, gestational age, delivery route, admission age, complaints, weight loss, and whether the infant was admitted to the NICU from home or from an obstetrics unit and hospital stay, were recorded. Physical examination findings, clinical and laboratory follow-up values, complications, and imaging methods used on patients in need were determined. Ethics committee approval for the study was received from Cumhuriyet University.

Sivas is a city with a population of 623,000, located in the Central Anatolia Region of Turkey. Neonatal unit of SSH is a registered secondary care unit with 22-bed capacity. Approximately 5,000 babies are born per year, and the annual number of infants that are hospitalized in the NICU is around 1,000. Infants who receive routine care after birth and have no health problem are followed along with their mothers at the obstetric unit.

Sivas State Hospital holds a baby-friendly hospital certificate, and infants who are followed up with their mothers in obstetric unit are breastfed as long as there is no contraindication. Vital finding follow-ups of infants who are kept with their mothers are performed by infant nurses in every 6 hours, and daily urination and defecation are followed. However, daily weight follow-ups of infants are not performed due to hospital's conditions. Mothers and infants are discharged from the hospital after 24 hours following normal spontaneous vaginal delivery and 48 hours after cesarean section.

Definitions

Dehydration is defined as losing more than 10% of the infant's birthweight at the end of the 1st week or the accompaniment of clinical findings with hypernatremia.¹³ Infants' weight loss was calculated with the formula [(birthweight − weight during examination)/birthweight × 100].

Infant's axillary body temperature >37.5°C was accepted as fever. Heart rate <80/min was evaluated as bradycardia. Plasma glucose levels below 50 mg/dL were accepted as hypoglycemia and above 125 mg/dL as hyperglycemia.¹⁸ High liver enzymes were accepted as aspartate aminotransferase (AST) >100 IU/L and alanine aminotransferase (ALT) >40 IU/L.¹⁹ Serum creatinine levels above 1.5 mg/dL and creatinine levels not decreasing for 24–36-hour follow-ups, despite the intravenous fluid intake, were defined as acute renal failure (ARF). The cases whose creatinine levels were decreasing following the intravenous fluid treatment and urination levels were ≥1 cc/kg/hour were accepted as prerenal ARF.²⁰

The guideline of American Academy of Pediatrics was used for the diagnosis and treatment of neonatal hyperbilirubinemia.²¹ Computed tomography (CT) and/or transfontanelle ultrasonography (TFUSG) were used for diagnosis of intracranial bleeding and brain edema.⁸ Renal parenchymal hyperechogenicity and nephrocalcinosis were evaluated by the same radiologist through abdominal ultrasonography. Convulsion was clinically defined after epileptic activity was shown through an electroencephalogram (EEG).

Follow-up protocol

All infants were examined by the physicians in the NICU and their perinatal histories, complaints, and physical examination findings were recorded. During admittance, serum Na, potassium, urea, creatinine, bilirubin, glucose, ALT, and AST samples were taken from all infants. Total body water loss = [(patient's serum Na level (mEq/L)/145) − 1] × total body fluid [(0.75 × patient's weight (kg)] formula was used according to the dehydration protocol of our clinic. Patient's maintenance fluid was calculated as 60–80–100–120 cc/kg/day on the 1st, 2nd, 3rd, 4th postnatal day, respectively, and 150 cc/kg/day on the 5th postnatal day and the following days. The number of days needed to enhance the deficit according to the hypernatremia level was, respectively, found to be 24, 48, 72, and 84 hours for those with serum Na levels between 145 and 157, 158 and 170, 171 and 183, and 184 and 196 mEq/L.

Serum Na reduction rate was aimed as 0.5 mEq/L/hour and maximum 12 mEq/L/day. Infants admitted with diagnosis of HD were identified with “mild HD” if their serum Na: 146–149 mEq/L (group 1) and “severe HD” if their serum Na ≥150 mEq/L (group 2).^12–14 The patients' electrolyte levels were checked in every 4–6 hours. Heart rate and oxygen saturations of all patients were continuously followed by using a pulse oximeter. Vital finding follow-ups were performed with 4-hour intervals, and physical examinations were performed routinely two times a day. Weight measurements were followed daily. Improvement of hypernatremia was defined as the decline of serum Na <145 mEq/L.

Statistical analyses

Statistical analyses were performed by using the SPSS version 16, Student's t test, Mann–Whitney U test, chi-square test, and the Fisher's exact test. Correlation analysis was performed through Spearman and Pearson correlation analyses. Statistical significance level was accepted as p < 0.05.

Results

Between September 2009 and September 2014, the number of born alive term and healthy infants was 22,676 in SSH and 159 of these infants were hospitalized with the diagnosis of HD. Accordingly, the frequency of HD among healthy term infants who were born in our hospital was 0.7%. Within the same period, 5,111 infants were admitted to NICU of SSH. The ratio of breastfed term infants who were hospitalized for HD was 3.1% (Table 1).

Table 1.

Demographic and Laboratory Characteristics of Hypernatremic Newborns (159 Cases)

Gender, female, n (%)	75 (47.2)
Gestational age, weeks^a	39 ± 1.2
Birthweight, g^a,b	3,371 ± 404 (2,500–4,500)
Admission weight, g^a,b	3,064 ± 396 (2,140–4,000)
Age of admission to hospital, day^a,b	3.15 ± 1.91 (1–16)
Length of hospitalization, day^a,b	3.09 ± 1.88 (1–13)
Weight loss, %^a,b	9.56 ± 4.20 (2.42–26.61)
Mother's age, year^a,b	26.32 ± 5.48 (15–43)
Parity, primipara, n (%)	96 (60.4)
Way of delivery, NSVD, n (%)	100 (62.9)
Place of birth, SSH, n (%)	133 (83.6)
Transferred from, home, n (%)	99 (62.3)
Season, summer, n (%)	87 (54.7)
Serum sodium level, mmol/L^a,b	152 ± 5.2 (146–185)
Serum creatinine level, mg/dL^b	0.9 (0.3–3)
Serum urea level, mg/dL^b	41.6 (8–259)
Total bilirubin level, mg/dL^b	9.5 (1.2–28.5)
Serum glucose level, mg/dL	63 (27–163)
Serum K level, mmol/L^b	4.9 (2–8)

Mean ± standard deviation.

Median (data range).

K, potassium; NSVD, normal spontaneous vaginal delivery; SSH, Sivas State Hospital.

Admission ages of infants with HD varied between 1 and 16 days. While their birthweights were between 2,500 and 4500 g, their weight loss ranged between 2.4% and 26.6%. The ratio of primiparous mothers was determined as 60.4%. In our study, positive correlations were found between the serum Na values and weight loss, admission age, hospital stay, admission to NICU after discharge, and serum urea levels (p < 0.05). No correlations were found between the serum Na levels and birthweight, season, maternal age, delivery route, and parity (p > 0.05).

Fever was the most common complaint reported by families, and 108 (67.9%) infants were taken because of fever. This was, respectively, followed by discomfort (37.1%), jaundice (27%), absence of sucking (23.3%), and decrease in urination–defecation (9.4%).

It was found that 68/159 patients were hospitalized with diagnosis of mild HD (group 1) and 91/159 were hospitalized with diagnosis of severe HD (group 2). Female/male ratio was calculated as 0.51 and 1.33 in the group 1 and 2, respectively, and the difference was found to be significant (p = 0.04). In group 1, 30 patients (44.1%), and in group 2, 69 patients (75.8%) have returned to the hospital and admitted to the NICU after they were discharged postbirth, and this ratio was found to be statistically significant (p < 0.001) (Table 2).

Table 2.

Characteristics of Group 1 and Group 2

Characteristics	Group 1n = 68 (serum Na: 146–149 mEq/L)	Group 2n = 91(serum Na ≥150 mEq/L)	p
Gender, male/female	45/23	39/52	0.04
Birthweight, g^a	3,320 ± 420	3,400 ± 380	0.24
Admission weight, g^a	3,050 ± 400	3,060 ± 390	0.70
Weight loss,% ^a,b	8.15 ± 3.1 (2.42–17.24)	10.61 ± 4.6 (2.7–26.61)	<0.001
Admission age, day^a,b	2.4 ± 0.7 (1–5)	3.7 ± 2.3 (2–16)	<0.001
Length of hospitalization, day^a,b	2.5 ± 1.1 (1–6)	3.5 ± 2.2 (1–13)	0.001
Mother's age, year^a	25.9 ± 5.2	26.7 ± 5.6	0.42
Way of delivery, NSVD, n (%)	42 (61.8)	58 (63.7)	0.79
Parity, primipara, n (%)	36 (52.9)	60 (65.9)	0.09
Transferred from, home, n (%)	30 (44.1)	69 (75.8)	<0.001
Season, summer, n (%)	36 (52.9)	51 (56)	0.69
Physical examination findings, n (%)
Oral mucosal dryness	45 (66.2)	76 (83.5)	0.01
Jaundice requiring PT	14 (20.6)	20 (22)	0.83
Turgor, tonus disorder	14 (20.6)	28 (30.8)	0.52
Weight loss ≥10%	18 (27.3)	40 (44.4)	0.02
Fever (>37.5°C)	33 (48.5)	63 (69.2)	<0.001
Laboratory findings^a
Admittance Na value (mEq/L)	147.5 ± 1.0	153.8 ± 5.6	<0.001
Urea (mg/dL)	32.4 ± 15.7	48.5 ± 35.4	<0.001
Creatinine (mg/dL)	0.87 ± 0.2	0.91 ± 0.4	0.74
Total bilirubin (mg/dL)	9.2 ± 3.4	9.7 ± 4.5	0.32
Glucose (mg/dL)	62.9 ± 1.8	67.1 ± 2.1	0.13
Potassium (mEq/L)	4.9 ± 0.7	5.0 ± 0.7	0.98
AST (IU/L)	62.9 ± 3.8	56.9 ± 2.4	0.10
ALT (IU/L)	22.7 ± 1.6	25.2 ± 1.5	0.16
Improvement time of hyperNa (hour)	21.7 ± 8.8	29.3 ± 17.8	0.03
Serum Na reduction rate (mEq/L/hour)	0.41 ± 0.3	0.50 ± 0.3	0.02

Statistical significance is indicated in bold font (p < 0.05).

Mean ± standard deviation.

Median (data range).

ALT, alanine aminotransferase; AST, aspartate aminotransferase; hyperNa, hypernatremia; Na, sodium; PT, phototherapy

No significant difference was found between the two groups in terms of prerenal ARF, hypo–hyperglycemia, convulsion, hyperpotassemia, and intracranial hemorrhage (Table 3).

Table 3.

Complications Observed in Group 1 and Group 2

Characteristics	Group 1	Group 2	p
Complications, n (%)
Prerenal ARF	2 (2.9)	6 (6.6)	0.46
Bradycardia	1 (1.5)	15 (16.5)	0.002
Hypoglycemia	17 (25)	18 (19.8)	0.43
Hyperglycemia	1 (1.5)	1 (1.1)	0.83
Convulsion	0 (0)	2 (2.2)	0.21
Intracranial hemorrhage	0 (0)	2 (2.2)	0.21
AST >100 IU/L	1 (1.5)	2 (2.2)	1.00
ALT >40 IU/L	4 (5.9)	10 (11)	0.26
Hyperpotassemia	4 (5.9)	5 (5.5)	1.00

Statistical significance is indicated in bold font (p < 0.05).

ARF, acute renal failure.

The most commonly observed nonmetabolic complication in our study was bradycardia and it was seen in 16 (10%) patients. Patients with bradycardia lost significantly more weight compared to infants without bradycardia (14.2% versus 9.0%, p < 0.001) and their admission ages (5.1 versus 2.9 days, p < 0.001) and hospitalization durations (5.7 versus 2.8 days, p < 0.001) have been found to be significantly longer. Serum Na levels of infants with bradycardia were also significantly more elevated compared to others during their admittance (155.8 versus 150.5 mEq/L, p < 0.001) However, the patients in group 2 had statistically higher rates of bradycardia. In group 2, 9/15 patients who developed bradycardia were provided with inotropic agent support.

It was found that 21/159 patients underwent renal ultrasonography and 10 patients suffered from nephrocalcinosis, renal parenchymal hyperechogenicity was observed in 3 patients, and 8 patients were interpreted as normal. According to the results of the TFUSG performed on 15 patients, 2 patients had germinal matrix hemorrhage. Both their hemorrhages were resorbed, and no neurological problems were observed during the follow-ups of these patients.

Another two patients had convulsion. One of these patients suffered a seizure on the 2nd day of her admission even though Na decrease rate was 0.37 mEq/hour. TFUSG and EEG were normal. No problems were observed in the neurological follow-ups. The other patient suffered a seizure and a cardiac arrest during her admittance, however, she was resuscitated and watched with ventilation support. Brain CT, TFUSG, and EEG were normal, and her neurological development was found to be normal. None of the eight patients who developed ARF needed dialysis, all ARF was treated with fluid replacement.

Even though only one patient had serious hyperbilirubinemia (postnatal 7th day, with bilirubin level: 28.5 mg/dL), his bilirubin levels decreased with fluid therapy and phototherapy, without the need of exchange transfusion. During the follow-up of this patient, no neurological and hearing problems have been observed (Table 4). All the patients were discharged. No patient died during the follow-up.

Table 4.

Major Complications in Newborns with Hypernatremic Dehydration

No.	BW (kg)	Age (days)	Weight loss (%)	Parity	Na (mEq/L)	Na reduction rate (mEq/L/hour)	Bradycardia ^a	Other complications
1	3.4	4	14.4	1	151	0.26	+	Hypoglycemia (glc: 33 mg/dL)
2	3.4	10	17.6	1	154	0.19	+	Liver dysfunction
3	3.25	3	10.1	3	156	0.62	+	Seizure, arrest (CPR+ventilated)
4	3.3	6	6.6	2	154	0.19	+	—
5	3.5	2	13.4	1	149	0.43	+	—
6	3.7	5	16.5	1	160	0.37	+	Hypoglycemia (glc: 32 mg/dL), ARF (urea: 73 mg/dL, Cr: 1.5 mg/dL) seizure, renal parenchymal hyperechogenicity
7	3.43	7	12.5	1	152	0.50	−	Indirect hyperbilirubinemia (Tbil:28.5 mg/dL)
8	3.75	5	16	1	150	0.36	+	—
9	3.27	16	26.6	1	174	0.34	+	ARF (urea: 259 mg/dL, Cr: 1.8 mg/dL), nephrocalcinosis, liver dysfunction
10	2.75	4	14.1	1	152	0.28	−	ICH (germinal matrix hemorrhage)
11	3.2	5	7.2	1	154	1.25	+	ARF (urea: 99 mg/dL, Cr: 1.7 mg/dL), hyperkalemia (K: 6.8 mEq/L)
12	3.4	5	14.7	3	162	0.41	+	Indirect hyperbilirubinemia (Tbil: 21.1 mg/dL)
13	3.35	10	21.2	1	185	0.70	−	ARF (urea: 212 mg/dL, Cr: 3.1 mg/dL), renal parenchymal hyperechogenicity, ICH (germinal matrix hemorrhage)
14	4.3	2	10	2	171	0.72	−	Hyperkalemia (K: 8 mEq/L), nephrocalcinosis, liver dysfunction

Bradycardia requiring treatment inotropic agents.

BW, birthweight; CPR, cardiopulmonary resuscitation; Cr, creatinine; Glc, glucose; ICH, intracranial hemorrhage; Tbil, total bilirubin.

Discussion

HD is considered as a serious health problem due to its mortality and morbidities that may develop during the treatment. It is more commonly seen among breastfed infants. It is difficult to determine the incidence of HD in newborns.²² In literature, this incidence was reported by Oddie et al.²³ as 2.5/10,000 live births, by Harding et al.²⁴ as 1.7, and by Konetzny et al.¹³ as 6/1,000 live births. In literature, hypernatremia frequency among breastfed term newborns was reported to be between 1.9% and 4.1%.^8,25,26 Similar to the literature, in the 5 years of study that we have conducted, the frequency of hypernatremia among the term infants who were born in our hospital was 7 in 1,000 live births and the ratio of infants who developed HD related to breastfeeding among the infants who were admitted to NICU was found to be 3.1%.

In various studies, mother's being primipara and having a cesarean section are considered as the most important risk factors for the development of HD.^6,27 While Livingstone et al.⁵ reported the rate of primipara mothers among infants with HD as 17%, Unal et al.⁸ stated this rate as 75%. Similarly, in our study, primipara rate among mothers was 60.4% (About 1.5 times more than the rate of primiparous mothers among all the childbirths that happened in our hospital, which is 42%) and caesarean section rate was 37.1%. We also did not find any significant difference between the two groups in terms of parity and delivery route. In concordance with the study of Bülbül et al.,¹⁴ we found no correlation between mother's age, delivery route, parity, and the serum Na values in our study.

Dehydration findings are generally concealed, as the fluid in the intracellular area transfers to the extracellular area during HD. Clinical findings are only noticed when dehydration reaches serious levels.²⁵ The most common complaint in the studies of Bülbül et al. and Erdemir et al. was fever, which was, respectively, 30.3% and 61.8%.^14,28 Similarly in our study, the most common complaint was fever with the rate of 67.9%. Fever was found to be significantly higher in patients of group 2. The average body temperature values on admission were statistically higher in group 2 (37.5°C versus 37.9°C, p < 0.001). A positive correlation was found between the serum Na value and the body temperature.

High rates of hyperbilirubinemia were also reported among patients with HD. Unal et al.⁸ reported that 47% of HD infants had complaints of jaundice during admittance and 74% of these were treated with phototherapy. The rates of jaundice were reported as 71% and 39.6% by the other researchers.^25,26 In our study, jaundice (27%) was the third common complaint after fever and discomfort. Phototherapy was used for 21% of our patients. This rate was lower compared to other studies. This may be associated with the early diagnosis of HD and the fact that phototherapy decision is made according to the measurement of bilirubin values.

Weight loss at the rate of 7% in the 1st week of life is considered as physiological, and the infant is expected to reach its birthweight on the 10th day of life.⁵ Particularly the infants who lost >10% of birthweight are accepted as high-risk for HD, and these infants should be evaluated more carefully in terms of breastfeeding and possible nutritional problems.²⁷ Manganaro et al.²⁷ reported that only 36% of breastfed infants who lost >10% of birthweight had hypernatremia and they found that the co-occurrence of serious weight loss (>10%) and hypernatremia was 3%. Oddie et al.²³ identified only 8/904 patients (0.9%) with hypernatremia who had serious weight loss (>10%). In addition, Unal et al.⁸ hospitalized 169 newborns due to HD, and the rate of infants who lost >10% of birthweight was 89.3%, whereas in similar studies, this rate was reported to be 88.6% and 73%.^8,25,26 In our study, this rate was found to be 36.4%.

Zachariassen and Juvonen indicated that HD may develop even if weight loss was <10%.²⁹ Willis and Livingston also reported that patients who had 6% to 9% of weight loss developed HD.⁵ Konetzny et al.¹³ did not encounter any relationship between Na levels and weight loss. It is hard to determine the normal range or the safe interval of weight loss among breastfed newborns. Even though it is not possible to provide such a safe weight loss range in our study, it has been found that a newborn who is breastfed and admitted with a weight loss ≥10% is 1.97 times more likely to have a serum Na value of ≥150 mEq/L compared to an infant with a weight loss of <10%. (OR: 1.97, 95 CL 1.0–3.8). This result coincides with the 10% threshold value, which was stated as the risk factor for HD in many studies.^{12,13,30–32}

Pelleboer et al. and Breuning-Boers et al. mentioned a relationship similar to our study regarding the serum Na value and a weight loss of ≥10%.^17,33 However, a significant difference was found between the two groups in terms of the ≥10% weight loss. Similar to our study, Moritz et al. and Boskabadi et al. reported a strong positive correlation between the serum Na levels and percentage of weight loss.^25,26

Although no data were found in previous studies, the most common physical finding determined in our study was oral mucosal dryness. A positive correlation was found between the serum Na value and oral mucosal dryness. In the light of our data, we have the opinion that even if the dehydration findings are not very clear, evaluating oral mucosal dryness and fever together in the physical examination of an infant who lost ≥10% of birthweight could determine the infants at risk for HD.

In our study, the infants accepted to NICU directly from the obstetrics unit were found to be at a significantly higher rate in group 1. The infants accepted to NICU from their home after being discharged were higher in numbers in group 2. Regarding this, the admission age of infants in group 2 was older. In our study, we have the opinion that the early diagnosis and hospitalization of infants with HD are related to the presence of infant nurses and the same pediatrician being responsible.

In our study, the time required for the patients admitted with HD to reach to serum Na <145 mEq/L was found to be 24.4, 40.9, 66.5, and 60 hours for the ones with Na values in between 145 and 157 (147 patients), 158 and 170 (9 patients), 171 and 183 (2 patients), and 184 and 196 (1 patient) mEq/L, respectively. As it was expected, the average time to reach to a serum Na <145 mEq/L in group 2 was longer than group 1.

Although there is no simple formula for improving HD among newborns, the best results in literature are obtained when the serum Na decrease rate is lower than 0.5 mEq/L/hour^34—36 This rate, which was faster than 0.5 mEq/L/hour, was shown to increase convulsion risk.³⁴ Although in our study the hourly serum Na decrease rate is in the acceptable range in both groups, it was significantly faster in group 2. As noted in previous studies, we have also found that as the level of hypernatremia of the patients increased, it became harder to regulate the fluid therapy in the desired intervals.³⁷

Serum Na >160 mEq/L is indicated as a risk factor for mortality and complications.^9,34 In our study, there was no correlation between the serum Na levels and the complications. This may be due to the fewer number of patients in our study with serum Na >160 mEq/L (six patients). However, no matter the level of hypernatremia, it should be kept in mind that patients might develop serious complications. Indeed, Pelleboer et al.¹⁷ reported convulsions in patients with Na: 148 mEq/L, and in our study, severe bradycardia was observed in one patient with Na: 149 mEq/L.

In our study, bradycardia was observed at a significantly higher rate among patients in group 2 (1.5% and 16.5%). Similarly, this rate was reported as 17% by Moritz et al.,²⁵ and Rowland et al.³⁸ indicated that a patient with the serum Na: 174 mEq/L developed bradycardia. Bradycardia may be developed as the effect of oxidative stress created by dehydration on myocardium or a complication of the treatment; however, more detailed studies on this subject are needed.

It should be noted that, frequent and effective breastfeeding, especially within the first postnatal 48 hours, is the golden key for the next successful breastfeeding period. Breastfeeding should be started as soon as possible after birth, and babies should be put to the breast whenever they want.^25,39 Breastfeeding support should be provided to all mothers by both healthcare workers and their relatives.³⁹ New mothers should be entirely focused on breastfeeding their babies without considering anything else. All parents should be informed in terms of neonatal dehydration signs. We believe that neonatal HD could be prevented by education, breastfeeding support, and close monitoring.

Our study is a retrospective one and has some limitations. The patients' data were obtained from hospital records. We do not have the data related to long-term neurocognitive developments, breast milk intake rates, and development growth conditions of patients diagnosed with HD and treated. More detailed studies to be conducted on the neurocognitive and physical developments of these patients in the long term are needed.

Conclusion

Although HD is a life-threatening disorder, serious complications can be prevented with early recognition and proper treatment. Ensuring successful breastfeeding after birth, informing families on dehydration symptoms, and performing weight follow-ups with frequent intervals for the first 10 days after birth would be effective to be protected from this condition. Even without any complaints, all newborns should be evaluated in terms of nutritional status and dehydration.

Footnotes

Acknowledgments

The authors thank Dr. Fatih Bolat, Dr. Tülay Akça, and Atilla Ünver for their contributions.

Disclosure Statement

No competing financial interests exist.

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