hypernatremia and its management in children

1. Hypernatremia management
B. Dormanesh
Professor of Pediatric Nephrology
AJA University of Medical Sciences

2. definition
Hyper excessive
natr prefix for Sodium
emia in the blood
Normal Sodium Na < 145 mEq/l
Mild hypernatremia 146 ≤ Na ≤ 149 mEq/l
Moderate hypernatremia 150 ≤ Na ≤ 169 mEq/l
Severe hypernatremia Na ≥170 mEq/l

3. Pathophysiology
Qi Qian: Hypernatremia , Clin J Am Soc Nephrol 14: 432–434, 2019

4. etiology

5. Signs & Symptoms
Acute hypernatremia
❑ CNS
( restless , confusion, lethargy, irritability , seizures , unconsciousness)
❑ Muscle
( muscle weakness)
❑ Unspecific
( nausea & vomiting , extreme thirst ,high pitched cry , doughy skin consistency)
❑ Risk for
( hypocalcemia , hyperglycemia )
Chisti MJ ,etall : Hypernatremia in Children With Diarrhea , Clin Pediatr (Phila). 2016 Jun;55(7):654-63. doi: 10.1177/0009922815627346
Chronic hypernatremia
( usually asymptomatic )

6. MRI in hypernatremia
brain shrinkage
(17 m. boy with acute hypernatremia )
intracranial hemorrhage – most often in the subdural space
(6 day. boy with severe acute hypernatremia )

7. Evaluation
Utility of urine and plasma osmolality in the evaluation of pediatric hypernatremia© 2022 UpToDate, Inc.

8. Management
I. Dehydration estimation
II. Initial resuscitation
III. Rate of sodium correction
IV. Calculate free water loss
V. Calculate sodium change
VI. prescribed fluid
VII. Fallow serum sodium concentration
VIII.Replace excessive ongoing losses
IX. Complication (seizure ) management
X. Underlying & specific interventions

9. I. Dehydration estimation
Note :
Patient is less symptomatic (normal BP , doughy skin) avoid underestimation
Case 1:
17 m. boy with diarrhea (2 days) with irritability , high pitched cry , normal BP ,decreased urination
Weight: 12.700
moderate dehydration
Na= 165 mEq/l , K = 3.5 mEq/l , BS = 205 mg/dl
severe dehydration

10. II. Initial resuscitation
Note :
LR or R shouldn’t be used , especially if multiple fluid boluses are necessary.
Osmolality
Mosm./l
Na+
mEq/l
Cl-
mEq/l
K+
mEq/l
Ca+
mEq/l
Lactate-
g/l
Normal Saline 308 154 154
Ringer 309 147 156 4 4
Lactated Ringer 275 130 109 4 3 28

11. III. Rate of sodium correction
Correction on basis of initial Na
[Na] mEq/L Time for correction
145 - 157 24 hr.
158 - 170 48 hr.
171 - 183 72 hr.
184 - 196 96 hr.

12. IV. Calculate free water loss
Total body osmoles = TBW × plasma osmolality
= TBW × plasma [Na]
In hypernatremia :
Current total body water(Current TBW) × plasma [Na] = normal body water(NBW) × 140
NBW = Current TBW ×
𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
free water loss (ml) = NBW – Current TBW
= (Current TBW ×
𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
) - Current TBW
= Current TBW ×
𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
− 1
= (05 or 0.6 ) × LBM ×
𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
− 1
Helmut G. Rennke & Bradley M. Denker in : Renal pathophysiology the essentials , 5th edition .,Wolters Kluwer, 2020

13. IV. Calculate free water loss
Free water (ml) = current TBW ×
𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
− 1
Free water (ml) = ( 4(ml) ) × ( weight (Kg)) × ( desired change in plasma Na)
Free water calculation in a 6 kg infant with Na = 165 mEq/l
Free water (ml) = 0.6 × 6 ×
165
140
− 1 = 0.61 𝑙 = 610 ml
Free water (ml) = 4 × 6 × ( 165−140) = 600 ml

14. V. Calculate sodium change
(Adrogué–Madias formula )
for the estimation of 1 L of any infuscate on serum Na+ concentration
Equation 1: TBW = weight (kg) x 0.6
Equation 2: Change in serum Na+ =
infusate Na+ − serum Na+
TBW + 1
Equation 3: Change in serum Na+ =
(infusate Na+ + infusate K+ ) − serum Na+
TBW + 1

15. VI. Prescribed fluid
Note :
• Avoid free water IV administration
• Mild to moderate hypernatremia can managed with ORS
• ORS is a hypotonic solution
• Patient also needs replacement of deficit & maintenance
• Avoid decrease rate > 0.5 mEq/l
• No need to correct hyperglycemia or hypocalcemia

16. VI. Prescribed fluid(cont.)
Case :
A 10 kg , 13 m. boy with diarrhea (2 days) referred to PICU due to unconsciousness and 10% dehydration ,
he have received one dose NS Na = 156 mEq/l K= 4.2 mEq/l BS = 280 mg/dl
➢ Total fluid deficit : BW × %𝑑𝑒ℎ𝑦𝑑𝑟𝑎𝑡𝑖𝑜𝑛 × 10 = 10 × 10 × 10 = 1000 𝑚𝑙
➢ Free water deficit : current TBW ×
𝑐𝑢𝑟𝑟𝑒𝑛𝑡 𝑝𝑙𝑎𝑠𝑚𝑎 𝑁𝑎
140
− 1 =0.6 × 10 ×
156
140
− 1 =686 ml
➢ Isotonic loss : TBW – free water deficit =1000 – 686 =314 ml
1 dose NS …..20 × 10 =200 ml
314 – 200 = 114 ml
➢ Rate of correction : Na correction < 10 mEq/l /day …….≅ 36 ℎ𝑟.
So in first 24 hr. just replace 2/3 free water
First 24 hr. free water =686 × 2/3 =480 ml

17. VI. Prescribed fluid(cont.)
➢ Free water deficit : 480 ml ( without Na)
➢ Isotonic loss : 114 ml ( with 17 mEq Na)
➢ Maintenance requirement :
BW × 100 𝑚𝑙 = 10 × 100 =1000 ml ( with 35 mEq Na +)
Sowe need 1600 ml IV fluid ( with 52 mEq Na+ )
1600 cc D5 ¼ NS
1600 cc D5 + 15.2 cc NaCl20%
65 ml/hr. D5 ¼ NS+ 20 mEq/l K
400cc D5 ¼ NS + 4 cc KCl 15%
over 6 hr.

18. VI. Prescribed fluid(cont.)

19. VI. Prescribed fluid(cont.)
Second method
Administer fluid at constant rate over time for correction
Typical fluid : D5 ½ NS + 20 mEq/l K
Typical rate : 1.25- 1.5 times maintenance
Case :
A 10 kg , 13 m. boy with diarrhea (2 days) referred to PICU due to unconsciousness
and 10% dehydration , he have received one dose NS
Na = 156 mEq/l K= 4.2 mEq/l BS = 280 mg/dl
1500 cc D5 ½ NS + 15 cc KCl 15%

20. VI. Prescribed fluid(cont.)

21. VII.Fallow serum sodium concentration
Note : Have tow IV solutions bedside
( D5 ½ NS and D5NS with the same K concentration)

22. VIII.Replace ongoing loss
clinicians will prescribe supplement needs ml as ml every 6-8 hr.

23. IX. Complication (seizure ) management
Published in The New England journal of medicine 2015
Disorders of plasma sodium--causes, consequences, and correction.R. Sterns

24. IX. Complication (seizure ) management (cont.)
Published in 2002
A Systematic Approach to the Hyponatremic PatientI. Ratković-Gusić, P. Kes, V. Basić-kes

25. IX. Complication (seizure ) management (cont.)
▪ Infusion 4 – 6 ml/kg hypertonic saline 3%
▪ Each 1 ml/kg saline 3% increases the serum Na ~ 1 𝑚𝐸𝑞/𝑙
Saline Hypertonic
3%
Na ( mEq/l) Cl ( mEq/l) Osmolality ( mOsm./l)
513 513 1026
How do you make a 3% salineSolution?
3 cc NaCl 5% + 2 cc sterile water
3 cc NaCl 20% + 17 cc sterile water

26. X. Underlying & specific interventions
▪ Salt poisoning
✓ Rapid correction ( hypotonic fluids)
✓ Furosemide
✓ Dialysis ( hemodialysis or CRRT )
▪ DI

27. Take home massage
❖ Hypernatremia is serum Na > 145 mEq/l
❖ Hypernatremia assessment starts with volume estimation and then Urine osm.
❖ The plasma Na shouldn’t be reduced > 10 mEq/l/day
❖ Risk of Cerebral edema in rapid correction of hypernatremia
❖ Calculate Free water deficit for IV therapy in hypernatremia
❖ Administer 1.25- 1.5 times maintenance from D5 ½ NS + 20 mEq/l K
❖ It s better to have two IV Solutions in bedside .