This document provides guidance on managing hypernatremia in children. It begins by defining hypernatremia as a serum sodium concentration over 145 mEq/L. It then discusses the pathophysiology, including mechanisms like water depletion and sodium excess that can cause it. Risk groups like infants and intubated patients are identified due to impaired thirst or access to water. The document proposes a simple formula of 60 ml/kg + maintenance fluids per day to correct hypernatremia at a safe rate of 0.5 mmol/L per hour, using hypotonic fluids like half normal saline. Regular sodium monitoring is advised to titrate fluids and avoid risks of overly rapid correction like cerebral edema.

1. Hypernatremia management
made easy!
Bashir Admani
Paediatric Nephrology

2. Hypernatremia
• Hypernatremia is defined as a serum sodium concentration
of more than 145 mEq/L. ( NORMAL SODIUM 140 MMOL/L)
• It is characterized by a deficit of total body water (TBW)
relative to total body sodium levels
– due to either loss of free water, or
– infrequently, the administration of hypertonic sodium solutions.1
• In healthy subjects, the body's 2 main defense mechanisms
against hypernatremia are thirst and the stimulation of
vasopressin release.

3. Pathophysiology
• The following 3 mechanisms may lead to
hypernatremia, alone or in concert:
• Pure water depletion
• Water depletion exceeding sodium depletion
• Sodium excess

4. Pathophysiology
• Sustained hypernatremia can occur only when
thirst or access to water is impaired.
Therefore, the groups at highest risk are
infants and intubated patients.

5. • Why should we discuss hypernatremia in
children????
• It is very common
• Hypernatremia itself is associated with high
morbidity and mortality
• If poorly managed, the management can lead
to morbidity and mortality

6. Epidemiology
• Estimated at about 1% of all admissions
• In developing countries it is estimated around
1.5-20%
• Associated with poor breastfeeding and
rehydration
• Diarrhea contributes to about 20%

7. Consequences
• Hypernatremia causes decreased cellular volume as a result
of water efflux from the cells to maintain equal osmolality
inside and outside the cell.
• Brain cells are especially vulnerable to complications
resulting from cell contraction.
• Severe hypernatremic dehydration induces brain shrinkage,
which can tear cerebral blood vessels, leading to cerebral
hemorrhage, seizures, paralysis, and encephalopathy.

8. Pathophysiology
• In patients with prolonged hypernatremia,
rapid rehydration with hypotonic fluids may
cause cerebral edema, which can lead to
coma, convulsions, and death.

9. Clinical features
• Physical
– Skin turgor is a physical finding in patients with
hypernatremia.
– Extracellular and plasma volumes tend to be
maintained in hypernatremic dehydration until
dehydration is severe (ie, when the patient loses
>10% of body weight).
– When dehydration is severe, skin turgor is
reduced, and the skin develops a characteristic
doughy appearance

10. Investigations
• Serum tests of sodium, osmolality, BUN, and
creatinine levels
• Urine tests of sodium concentration and
osmolality
– In cases of hypovolemic hypernatremia, extrarenal
losses show urine sodium levels of less than 20 mEq/L,
and in cases of renal losses, urine sodium values are
more than 20 mEq/L.
– In euvolemic hypernatremia, urine sodium data vary.
– In hypervolemic hypernatremia, the urine sodium
level is more than 20 mEq/L.

11. Management of Hypernatraemia
• Based on cause:
– Replace water lost
• Free fluid deficit replacement
• Reducing loss of free water –diabetes insipidus
– Remove excess sodium
• Water + diuretics
• Haemodialysis

12. Dr Bashir Admani

13. Free Fluid Deficit
• Formula:
K x BdWt measured [Na+]
expected [Na+]
– K = dependant on TBW =
• 0.6
– Expected [Na+] = 140 mmol/L
-1

14. Administration of Fluid
• FFD + fluid for isonatraemic dehydration
+ maintenance fluid
• Aim to reduce sodium by 0.5 mmol/hr*
• Use of commercially prepared fluids
*Kahn, A, Brachet, E, Blum, D. Controlled fall in natremia and risk of seizures in hypertonic dehydration. Intensive Care Med 1979;
5:27.
*Blum, D, Brasseur, D, Kahn, A, Brachet, E. Safe oral rehydration of hypertonic dehydration. J Pediatr Gastroenterol Nutr 1986;
5:232.

15. Example
• 10 kg, 1 year old child with diarrhoea and
serum sodium 160 meq/l
FFD : 0.6 x 10 160 = 0.85 L
140
Assumption of 10% dehydration: so isotonic losses
.15 litres
Maintenance fluid in 24 hrs = 1.0L/24 hrs
-1

16. • Correction would should not be faster than
0.5 mmol/hr
• So to correct to 140 mmol/l from 160 mmol/l
you need 20 x 2 hrs=40 hrs
• First 24 hrs: 24/40 x 1000ml=600ml
• Plus maintence fluid: 1000ml
• Total in 24 hrs: 1600ml

17. • If the serum sodium was 170mmol/l
• Free fluid deficit: 0.6 x 10 (170/140-1)
• 1285 ml
• Total dehydration: 15%
• Isotonic losses 215ml
• Correction over 60hrs
• In 24 hrs; 24/60 x 1500ml: 600ml plus
maintenance

18. • If the serum sodium was 180mmol/l
• Free fluid deficit: 0.6 x 10 (180/140-1)
• 1715 ml
• Total dehydration: 20%
• Isotonic losses 285ml
• Correction over 80hrs
• In 24 hrs; 24/80 x 2000ml: 600ml plus
maintenance

19. SO WHY IS NEPHROLOGY SO
DIFFICULT?

20. OBSERVATIONS WITH FORMULA
• Difficult to remember so usually not used
properly
• Free fluid deficit is used to calculate the whole
replacement and children and fluids are
undercalculated
• Extremely dilute fluids used bringing down the
sodium level too fast leading to brain oedema

21. No magic

22. Simple formula…Bashir’s formula
• From the understanding from our calculations of
free fluid deficit and dehydration
• The assumption is made that children with
hypernatremia would be dehydrated increasingly
with the level of sodium
• 150 mmol/l-5%
• 160mmol/l- 10%
• 170mmol/l-15%
• 180mmol/l-20%

23. • From the calculations for free fluid deficit and
amount of fluid to be given
• I have come up with a single equation to
calculate fluid management in hypernatremic
dehydration
• 60ml/kg +maintenance fluid every 24 hrs
• As long as required to calculate sodium excess

24. If sodium is at 160mmol/l
Using free fluid deficit
calculation
• If the serum sodium was
160mmol/l
• Free fluid deficit: 0.6 x 10
(160/140-1)
• 850 ml
• Total dehydration: 10%
• Isotonic losses 150ml
• Correction over 40hrs
• In 24 hrs; 24/40 x 1000ml:
600ml plus maintenance
• 1600 ml in 24 hrs
My formula
• 60 ml/kg + maintenance
fluid
• (60 x 10) + 1000 ml
• 1600 ml in first 24 hrs

25. If sodium is at 170mmol/l
Using free fluid deficit
calculation
• If the serum sodium was
170mmol/l
• Free fluid deficit: 0.6 x 10
(170/140-1)
• 1285ml
• Total dehydration: 15%
• Isotonic losses 215ml
• Correction over 60hrs
• In 24 hrs; 24/60 x 1500ml:
600ml plus maintenance
• 1600 ml in 24 hrs
My formula
• 60 ml/kg + maintenance
fluid
• (60 x 10) + 1000 ml
• 1600 ml in first 24 hrs

26. If sodium is at 180mmol/l
Using free fluid deficit
calculation
• If the serum sodium was
180mmol/l
• Free fluid deficit: 0.6 x 10
(180/140-1)
• 1715ml
• Total dehydration: 15%
• Isotonic losses 385ml
• Correction over 80hrs
• In 24 hrs; 24/80 x 2000ml:
600ml plus maintenance
• 1600 ml in 24 hrs
My formula
• 60 ml/kg + maintenance
fluid
• (60 x 10) + 1000 ml
• 1600 ml in first 24 hrs

27. What fluid??
• Since there is free fluid deficit best to use
hypotonic fluids like half normal saline
• And titrate it by doing regular sodium levels
• Very important that the fall should not be
abrupt or else you may get cerebral edema
and seizures

28. How long do you treat
• Correct sodium at a rate of 0.5 mmol per hour
• So if sodium is 160 mmol/l, you correct over
40 hrs
• 170 mmol/l-over 60 hrs
• 180 mmol/l – over 80 hrs

29. • Hypernatremic dehydration is associated high
morbidity and mortality
• Easier way to manage possibly using formula
60 ml/kg plus maintenance fluid
• Fluid regimen to correct sodium at rate of .5
mmol/l per hour
• Use hypotonic fluid, best being half saline
In summary
Dr Bashir Admani

30. We keep thinking and evolving!!!
initially calculate
losses
bashirs formula
reassessment 40
ml/kg
+maintenance fluid
Noticed that the
correction was
faster than wanted

31. THANK YOU FOR STAYING AWAKE
• THANK YOU FOR STAYING AWAKE

32. • Thank you