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Case Reports Indian Pediatrics 2002; 39:193-196 |
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Neonatal Hypernatremia Due to High Breast-milk Sodium |
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Anurag Bajpai Rajiv Aggarwal Ashok K. Deorari Vinod K Paul
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.
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.
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
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