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

The Diagnosis of Salt Poisoning Leading to Hypematraemia in Children – September 2009
5. Lethal dose of salt
5.1 What is thought to be a lethal dose of salt?
A number of publications have estimated the likely lethal dose of salt, based on case
reports of death following salt ingestion. Most, but not all, reports are of acute ingestion
rather than chronic ingestion.
A case report in an adult who drank a known quantity of Shoyu sauce and subsequently
died 254 estimated that the dose was 2.5 g/kg body weight. Other estimates in the literature
150, 223, 279
suggest a lethal dose in the range of 0.75 to 3 grams per kilogram body weight.
There are very small numbers of case reports in the literature in which the dose of salt and the
child’s size are accurately known from the publication. The smallest amount of salt associated
with the death of an infant was reported in a German case in 1976 159 (case 2) . 5 grams of salt were
given in error to a 9-week-old baby (this would suggest a dose of around 1 g/kg body weight).
A second case was reported from Australia in 1971 180 , in which a 22 month infant weighing
12.3 kilogram died after administration of 1 pint of 5% saline as an emetic. The dose of salt was
therefore 2.3 g/kg body weight. As some may have been vomited, the amount actually ingested
may have been smaller. In the other cases where the dose and child’s weight were both known,
the quantities of salt were larger relative to their size.
Evidence statement
The minimum amount of salt that could be fatal to an infant or child is likely to be in the
range of 0.75 to 3 g/kg (approximately 13 to 51 mmol) body weight [Grade C].
5.2 How is the dose of sodium required to raise the serum sodium
by a specified amount calculated?
This question can be critically important in providing courts with information about the
likely amount of sodium needed to raise the serum sodium by a specified amount.
Although sodium is principally distributed in the extracellular space, the free movement
of water between the intracellular and extracellular spaces means that there is a very rapid
shift of water out of the cells to re-establish the osmotic equilibrium. The original basis
for this approach is to be found in a seminal paper by Edelman published in 1958. 280 Two
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