The differential diagnosis of hypernatraemia in children, with ...

The Diagnosis of Salt Poisoning Leading to Hypematraemia in Children – September 2009
The infant had inadvertently been fed bottles for 72 hours containing 23 grams per litre of
sodium chloride. He was said not to have finished his bottles, and it was not possible to
calculate his sodium intake before admission.
In a second case, the mother had inadvertently substituted salt for sugar in making up an oral
rehydration solution for diarrhoea 169 . The infant’s sodium chloride intake was estimated to
have been 25 to 30 grams in the 24-hour period up to 12 hours before admission. Treatment
included peritoneal dialysis, which would have removed a significant amount of sodium
and chloride. The 24-hour urinary sodium losses in the 2 days after admission were 45 and
19 mEq, or 6.3 and 2.7 mEq/kg respectively. The 24-hour urinary chloride losses were 34
and 28 mEq, or 4.7 and 3.9 mEq/L respectively. Serum sodiums were 200 and 160 mEq/L
at the start of each of these two days.
A third infant aged 5 weeks in whom salt had inadvertently been substituted for sugar 244
had 24 hour urinary volumes and urinary sodium and chloride concentrations measured
up to 8 days after admission. The excessive salt intake was estimated to have been 30 to
40 grams of sodium chloride. No peritoneal dialysis was undertaken. The 24-hour urinary
sodiums and chlorides were as follows:
Day 1: Na + 1.6 mEq/kg Cl - 1.3 mEq/kg (serum Na + 193, Cl - 157)
Day 2: Na + 2.4 mEq/kg Cl - 2.1 mEq/kg (serum Na + 161, Cl - 135)
Day 3: Na + 4.1 mEq/kg Cl - 3.3 mEq/kg (serum Na + 161, Cl - 127)
Day 5: Na + 4.5 mEq/kg Cl - 3.0 mEq/kg (serum Na + 154, Cl - 115)
Day 8: Na + 0.9 mEq/kg Cl - 0.7 mEq/kg (serum Na + 142, Cl - 105)
The urea was 48 mg/100ml at 24 hours and fell to 16 mg/100ml by day 8. This
case demonstrated delayed urinary excretion of sodium and chloride, and particularly
demonstrates the value of continuing to monitor 24-hour urinary output until the serum
sodium and chloride normalise.
6.2.3.1 Normal 24 hour urinary sodium
The literature search was also designed to identify any studies of normal values for
24-hour urinary sodium excretion rates in infants, children or adults; and also of
studies reporting 24-hour urinary sodium excretion rates in children with diarrhoea
and dehydration. References were also searched in the appraised papers for other
relevant studies.
A literature search found only a few studies measuring 24-hour urinary sodium in
healthy infants and children. Most reported absolute output but not output expressed
per body weight.
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