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Case Reports

Indian Pediatrics 2002; 39:193-196  

Neonatal Hypernatremia Due to High Breast-milk Sodium

 
Anurag Bajpai
Rajiv Aggarwal
Ashok K. Deorari
Vinod K Paul

From the Division of Neonatology, Department of Pediatrics, All India Institute of Medical Scinces, New Delhi 110 029, India.

Correspondence to: Dr. Rajiv Aggarwal, Assistant Professor, Department of Pediatrics, All India Institute of Medical Scinces, New Delhi 110 029, India.

E-mail: [email protected]

Manuscript received: April 25, 2001;
Initial review completed: June 20, 2001;
Revision accepted: July 12, 2001.

Hypernatremia associated with elevated breast milk sodium is a rare cause of neonatal hypernatremia(1-3). Malnutrition has been implicated as the major cause of hypernatremia in these cases; elevated breast milk sodium playing a secondary role(4-6). We present a series of three neonates on exclusive breastfeeding who developed severe hypernatremia with features of sodium load and elevated sodium levels in mother’s breast milk. The neonates were managed with stopping breast-feeds.

Case Report

Case 1: This girl presented at day 20 of life with fever for 5 days, decreased feeding and lethargy for 2 days and tightening of skin for 1 day. She had been discharged on day 3 of life after an uneventful postnatal period. She was exclusively breastfed and used to feed 8-10 times a day. Mother felt that the child was contended with feeds and urine and stool output was adequate. On examination the child was lethargic and had a shrill cry. Her heart rate was 160/min, respiratory rate 48/min, capillary refill time 2 seconds and blood pressure 60/32 mm Hg. She had lost 900 grams (30%) since birth. Skin was doughy and features of some dehydration were present. Systemic examination was within normal limits.

Relevant clinical details and investigations are summarized in Table I. Septic screen, cerebrospinal examination and arterial blood gas were normal. In view of hypernatremia with significant weight loss and dehydration, the diagnosis of hypernatremic dehydration was considered. Elevated urine specific gravity favored the diagnosis. However, elevated levels of urinary sodium indicated a form of sodium load. Since the child was exclusively breast-fed and there was no exogenous sodium load the only probable source was the breast milk. Sodium in mother’s breast milk was 90 mEq/L (Normal values 7 + 2 mEq/L)(7). Levels of breast milk sodium done in 4 mothers used as conrols ranged from 10-20 mEq/L. Serum sodium and potassium in the mother was 130 mEq/L and 3.7 mEq/L respectively. There was no evidence of mastitis and sweat chloride level was 27 mEq/L. Breastfeeding was stopped and the child managed with fluids appropriate for hypernatremia. The child demonstrated a rapid fall in the sodium levels (20 mEq/L in 16 hours) and she developed seizures. Renal functions showed gradual improvement over the next 6 days. Repeated estimations of the mother’s breast milk showed elevated sodium levels even after 15 days. The child was discharged on formula feeds.

Cases II and III: We identified two more cases with similar problems. Relevant clinical and laboratory findings are summarized in Table I. All the infants were exclusively breastfed. The urine output and stool frequency were normal. Hypernatremia was associated with elevated urine specific gravity, urinary sodium, deranged renal functions and elevated breast milk sodium. Similar to previous case there was a precipitous decrease in serum sodium after fluid correction. In contrast to the index case breast milk sodium normalized over 5 and 6 days respectively.

Table I__Comparison of Clinical and Laboratory Features of Cases
Features Case I Case II Case III
Parity Primigravida Primigravida Primigravida
Sex Female Female Male
Birth weight (g) 3100 3300 3000
Age at presentation (days) 20 10 18
Presenting features Fever Lethargy Dehydration Fever Lethargy Dehydration Fever Lethargy
Weight loss (% of birth weight) 30 27 28
Serum sodium (mEq/L) 186 189 163
Serum potassium (mEq/L) 3.1 5.1 4.1
Urea (mg/dl) 162 100 96
Serum creatinine (mg/dl) 2.1 1.6 1.4
Urine specific gravity 1040 1030 1031
Urinary sodium (mEq/L) 102 61 102
Breast milk sodium (mEq/L) 92 34 30
Rapid fall in sodium Yes Yes Yes
Complications of therapy Seizures None None
Follow up Formula feed Breast feed Breast feed
Normal breast milk sodium - 7 ± 2 mEq/L

Discussion

High urinary sodium and specific gravity in association with hypernatremia points to sodium load being the etiological agent. Elevated breast milk sodium indicates that breast milk was the source of sodium load. Hypernatremia due to high breast milk sodium is an established entity(1-3). This has been attributed to dehydration and malnutrition due to low breast milk production although high breast milk sodium may also play a role(4-6). Reports of this entity in the literature are summarized in Table II.

The interesting finding in these neonates is elevated urinary sodium, which points towards an important role of high breast milk sodium. Breast milk sodium was significantly and persistently elevated in Case 1; elevated breast milk sodium thus appears to be the major etiological factor in this case. In Cases 2 and 3 breast milk sodium was lower than Case 1 and normalized within a week. It is plausible that they represent the classical form of breast-milk related hypernatremia where malnutri-tion rather than elevated breast milk sodium is the major etiological factor.

The cause of high breast milk sodium is not clear in present cases. Mastitis has been associated with elevated breast milk sodium but was absent in all these cases(9). Adrenal insufficiancy and cystic fibrosis increase sodium excretion across the sweat glands and could increase breast-milk sodium, as breast gland is a modified sweat gland. There were no features suggestive of cystic fibrosis in the mothers and sweat chloride was normal in Case 1. Normal levels of serum sodium and potassium rule out clinically significant adrenal insufficiency in the mothers. Persistently elevated breast-milk sodium in Case 1 may be related to sub-clinical adrenal insufficiency or limited form of pseudo-hypoaldosteronism. The same could not be confirmed as peripheral renin activity and aldosterone levels were not available.

Table II__Neonatal Hypernatremia and High Breast-milk Sodium-Review of literature
Study Age Sex Presentation Weight loss (%) Serum sodium (mEq/L) Breast milk sodium (mg/L) Course
Anand(1) 14d M Lethargy Jaundice 40 190 31 Formula feeds
18d F Dehydration 30 202 74
Roddey(4) 4d M Lethargy 33 190 48 Seizures ARF
Rowland (5) 10d M Apnea Lethargy 27 174 44 Top feeds
15d F Oliguria Lethargy 40 208 Seizures Hypoglycemia
Arboit (3) 15 d M Dehydration Malnutrition 30 180 104 Seizures DIC FND
Ghishan (6) 20d M Lethargy Dehydration 30 189 41 Seizures Breast-fed
14d F Oliguria Lethargy 37 195 57 Seizures Breast-fed
Thullen (8) 14 d M Shock Jaundice 15 189 74 Breast-fed
Present series 20d F Fever Dehydration 30 186 90 Seizures Formula feeds
10d F Fever Malnutrition 27 190 34 No seizures Breast-fed
18d M Fever Malnutrition 27 163 30 No seizures Breast-fed
ARF - Acute renal failure, DIC - Disseminated intravascular coagulation FND-Focal neurological deficit.

Hypernatremia is managed with gradual correction over 48-72 hours by calculation of free water deficit and level of dehydra-tion(10). This correction is intended to cause gradual reduction in serum sodium (0.5 mEq/kg/hour). Patients with sodium load are however prone to precipitous fall of serum sodium levels once the load is removed making close monitoring of sodium levels mandatory. Rapid fall in serum sodium (1.5 mEq/L/hour) in these cases points towards breast milk being an important factor in these cases. In most cases of breastfeeding mal-nutrition-related hypernatremia, breast milk sodium decreases with time and neonates can be started on breast-milk once they have stabilized(8).

These findings emphasize the need of estimation of breast-milk sodium in exclu-sively breast-fed neonates presenting with hypernatremia in association with elevated uirnary specific gravity and sodium. Breast-feeding counseling and evaluation of adequacy of lactation in mothers with in-adequate experience in child rearing is essential in preventing the condition. Evalua-tion of neonates at risk at two weeks of age may help in preventing the devastat- ing short and long-term consequences of hypernatremia.

Contributors: All the authors were involved in the case management. AB did the literature search and drafted the manuscript along with RA. VKP and AKD reviewed the manuscript. RA will act as the guarantor of the article.

Funding: None

Competing interests: None stated

Key Messages

• Elevated breast milk sodium is a rare but often missed cause of neonatal hypernatremia.

• Breast milk sodium levels should be estimated in exclusively breast-fed neonates with hypernatremia and elevated urinary specific gravity and sodium.


 References

 

1. Anand SK, Sandborg CS, Robinson RG, Lieberman E. Neonatal hypernatremia associated with elevated sodium concentration of breast milk. J Pediatr 1989; 96: 66-68.

2. NG PC, Chan JB, Lee CH, Chan KM, Wong W, Cheung KL. Early onset of hypernatremic dehydration and fever in exclusively breast-fed infants. J Pediatr Child Health 1999; 35: 585-587.

3. Arboit JM, Gildengers E. Breast feeding and hypernatremia. J Pediatr 1989; 97: 335-336.

4. Roddey OF, Martin ES, Swetenburg RL. Criticial weight loss and malnutrition in breast-fed infants. Am J Dis Child 1989; 135: 597-599.

5. Rowland TW, Lafleur WR. Malnutrition and hypernatremic dehydration in breast-fed infants. JAMA 1982; 247: 1016-1017.

6. Ghisnan FK, Roloff JS. Malnutrition and hypernatremic dehydration in two breast-fed infants. Clin Pediatr 1983; 22: 592-594.

7. Koo WW, Gupta JM. Breast milk sodium. Arch Dis Child 1982; 57: 500-502.

8. Thullen DJ. Management of hypernatremic dehydration due to insufficient lactation. Clin Pediatr 1988; 27: 370-372.

9. Ramadan MA, Salah MM, Eid SZ. The effect of breast infection on the composition of human milk. J Reproductive Med 1972; 128: 84-87.

10. Cronan K, Norman NE. Renal and electrolyte emergencies. In: Textbook of Pediatric Emergency Medicine, 4th Edn. Eds. Fleisher GR, Ludwig S. Philadelphia, Lippincott, Williams and Wilkins, 2000; pp 816-817.

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