Abnormal Sodium
National Pediatric Nighttime Curriculum
Written by Julia Aquino, MD
Floating Hospital for Children at Tufts Medical Center
Learning objectives
After this module learners will be able to:

Describe principles of acute fluid management in the
correction of hypernatremia and hyponatremia

Recognize the signs and symptoms that require
immediate attention in patients with disordered sodium

Consider the level of care appropriate for patients
requiring correction of hypernatremia and hyponatremia
Case #1 (intern)

You have just finished sign out and you
are reviewing your patient list to prioritize
the most ill patients when your pager goes
off:

“Lab called with critical value for patient in
735: sodium 160. Please advise.
–Kevin”
You review your sign out…

7 month old otherwise healthy male admitted
directly from clinic in the late afternoon with
gastroenteritis and dehydration. He has had
minimal PO intake and decreased urine output.

Tachycardic and febrile when the admitting team
saw him but otherwise stable.

Overnight plan: floor staff is placing an IV, giving
a 20cc/kg NS bolus and will call night team to
reassess when complete.
You head to room 735
As you go to the bedside to assess the
patient, you review some questions:





What are possible etiologies of hypernatremia?
What about in this patient specifically?
What do I need to worry about immediately?
Should I call my senior?
Can I take care of this patient on the floor or
does he need a higher level of care?
At the bedside

VS: T 38.5, HR 120, RR 30, BP 90/60, O2 sat 99% RA

His nurse, Kevin, tells you that the NS bolus is almost
complete and that the patient has been irritable since
arriving to the floor

Physical exam: General: irritable infant; HEENT:
mucous membranes dry, anterior fontanelle slightly
sunken; Chest: clear; CV: tachycardic, regular rhythm,
II/VI systolic ejection murmur; Abdomen: soft,
hyperactive bowel sounds; Extremities: normal skin
turgor, cap refill 3 seconds

What is your overall assessment of this patient?

What is your next step?
Stop the bolus—this patient is
hypernatremic and NS is an inappropriate
fluid choice
B) Give another 20cc/kg bolus of NS
C) Call a renal consult
A)
Next steps
You give another normal saline bolus and the
patient’s perfusion, heart rate and mental
status start to normalize
Kevin asks you what fluids you want to hang
now….


What do you need to consider when
correcting the sodium in hypernatremic
dehydration?
What do you need to worry about if correcting
too fast?
Calculating free water deficit

Free water deficit is the minimum amount of fluid
necessary to correct serum sodium

Estimate of free water deficit:
4mL x body weight x desired change in sodium

Goal is to correct sodium at a rate no faster than
0.5 mEq/L/hour

Add maintenance fluid needs and account for
any ongoing losses
Ongoing management

What fluid should you choose?

When should you recheck a sodium?
Hypernatremia

Defined as serum sodium >/= 145mEq/L

Causes:
Excess sodium intake
Concentrated formula, salt ingestion (seawater,
accidental, Munchausen-by-proxy), hypertonic
IV fluids, sodium bicarbonate, blood products
Increased free water losses
1) Renal: diabetes insipidus, diuretics, tubular
disorder
2) GI: diarrhea, vomiting, colostomy/ileostomy
output, malabsorption
3) Insensible: fever, tachypnea, burns
Decreased free water intake
Ineffective breastfeeding, poor access to water,
blunted thirst mechanisms, fluid restriction
Clinical Manifestations and
Evaluation of Hypernatremia

Early neurologic signs include agitation and
irritabilitycan progress to seizure and coma

Neurologic exam can reveal increased tone,
brisk reflexes and nuchal rigidity

Lab evaluation can include:
 Serum
osmolarity
 Serum glucose
 Urine osmolarity and specific gravity
Neurologic Sequelae

In acute phase:
 Intracellular
fluid moves to extracellular spacevolume loss in brain
separation from meninges

If hypernatremia has existed for >2-3 days:
 Neurons
protect themselves by making osmolytes to
maintain gradient
 With rapid correction, neurons can swell leading to
cerebral edema

Mortality estimated at 10-16% despite
correct rate of rehydration
Case #2 (senior)
You are doing your late evening rounds on
the ward when one of the nurses pulls you
aside:

“One of the post-op orthopedic patients
has a sodium of 115 and I can’t reach the
primary team. Can you help me?”
His nurse gives you more info…



Patient is a 16yo with cerebral palsy and
global developmental delay who is postoperative day #2 from posterior spinal fusion.
He has been wretching and not tolerating gtube feeds so has been on maintenance IV
fluids of D5 ½NS + 20mEq/L KCl all day.
His mother is at the bedside and feels he is
not himself.
At the bedside

VS: T 38.0, HR 90, BP 100/75, RR 20, O2
98%RA

General: neurologically impaired child moaning in bed,
less responsive to voice/touch per mother; HEENT: lips
dry, mucous membranes slightly dry; Chest: CTAB; CV:
RRR, nl S1, S2; Abdomen: g-tube intact, hypoactive
bowel sounds; Extremities: well perfused; Neuro:
increased tone and spasticity in extremities, responds to
voice with a moan, responsive to painful stimuli
Next steps

You initiate a rapid response and transfer
to the PICU should happen shortly. Your
immediate next step should be:
A) Prompt
administration of hypertonic saline
(3%)
B) Emergent head CT
C) Fluid restriction due concern for SIADH
Your patient stabilizes…
Your patient is returning to baseline mental
status and you stop the hypertonic saline.
What general guidelines do you use to
think about ongoing fluid management?
 Why are you worried about the rate of
correction?

Hyponatremia

Defined as serum sodium </=135

Occurs in 3% of hospitalized patients

Kidney protects against hyponatremia by
excreting free water as dilute urine
 Hyponatremia
is an increase in total body
water rather than a decrease in serum sodium
Causes of hyponatremia
Decreased total body water
GI losses (diarrhea, emesis), diuretics, RTA,
3rd spacing
Increased total body water
CHF, acute renal failure, SIADH, water
intoxication (dilute formula feeding)
Normal total body water
Hypoglycemia
Pseudohyponatremia
Severe hyperlipidemia or hypoproteinemia
•Hyperglycemia leads to hyperosmolarity with translocation of
fluids from intracellular to extracellular space
•Pseudohyponatremia: displacement of plasma water resulting in
falsely low serum by laboratory measurement
Clinical manifestations of
hyponatremia

Neurologic symptoms related to edema caused
by hypo-osmolarity

Children at higher risk due to higher brain-to-skull ratio

Symptoms include headache, nausea, emesis,
weakness

Severity worsens as edema increases leading to
signs of cerebral herniation

Respiratory changes, posturing, pupillary changes, seizure
Lab evaluation of hyponatremia

Serum osmolarity if concerned for
pseudohyponatremia

Urine osmolarity to evaluate for impaired ability to
excrete free water

Urine sodium



<25 mEq/L consistent with volume depletion
>25Meq/L consistent with renal tubular dysfunction, SIADH,
diuretic use
Must be interpreted with caution since affected by IV fluids, fluid
restriction, diuretic use
Fluid management goals

Hyponatremia with neurologic symptoms is a
medical emergency
Clinical picture
Fluid
Rate
Seizure
3% hypertonic saline
raise serum sodium by 4-8
mEq/L/hour until seizure
activity stops
No seizure activity but
not at neurologic
baseline
3% hypertonic saline
raise serum sodium by
1mEq/L/hour until:
-patient at baseline
-plasma sodium increases
by 20-25mEq/L OR
-serum sodium increases to
125-130mEq/L
Asymptomatic
0.9% normal saline
raise sodium no faster than
0.5 mEq/L/hour
Why are we concerned about the
rate of correction?

Excessive changes in serum sodium can lead to cerebral
demyelination (central pontine myelinolysis)



Recent data shows rate of correction may have little
affect on development of demyelination


Usually occurs several days after correction
Presents with confusion, quadriplegia, confusion or pseudocoma
Magnitude of correction and underlying illness more important
contributing factors
Risk of untreated hyponatremia far exceeds that of rapid
correction so do not hesitate to use hypertonic saline
for symptomatic patients
Key learning points

Always prioritize hemodynamic stability over sodium
correction

Correction calculations for both hypernatremia and
hyponatremia are general guidelines—sodium should be
monitored frequently to ensure safe rate of correction

Symptomatic hyponatremia is a medical emergency and
should be managed in a closely monitored setting with
3% hypertonic saline
References

Chung C, Zimmerman D. Hypernatremia and
hyponatremia: current understanding and management.
Clin Ped Emerg Med. 2009; 10: 272-278.

Moritz M and Ayus JC. Disorders of water metabolism in
children: hyponatremia and hypernatremia. Pediatr Rev.
2002; 23: 371-380.

Schwaderer AL, Schwartz GJ. Treating hypernatremic
dehydration. Pediatr Rev. 2005; 26: 148-150.

Waseem M, Hussain A. Index of suspicion. Pediatr Rev.
2004; 25: 397-399.
Questions:
1) A 1 month old patient with RSV bronchiolitis and
dehydration develops vomiting and altered mental
status leading to generalized a tonic-clonic seizure.
Her serum sodium is 118 mEq/L. The most likely
mechanism for her clinical deterioration is:
A) Demyelination
B) Cerebral edema
C) Brainstem herniation
D) Intracranial hemorrhage
Questions:
A)
Incorrect. Demyelination can occur as result of hyponatremia,
but it usually presents several days following the change in sodium
with confusion, pseudocoma or a “locked-in” state. Recent data
suggests that it is not the rate of correction that leads to
demyelination, rather the magnitude of correction necessary and the
underlying illness.
B)
Correct. Hyponatremia leads to an influx of fluid from the
extracellular space to the intracellular space cause cerebral
edema. Early neurologic manifestations including headache,
vomiting, seizure and altered mental status are a direct result.
C)
Incorrect. Cerebral edema from hyponatremia can lead to
brainstem herniation, but this would present with respiratory arrest,
asymmetric pupillary changes or decorticate posturing.
D)
Incorrect. Hyponatremia rarely leads to intracranial
hemorrhage. Hypernatremia can cause this due to acute loss of brain
volume from loss of fluid from the intracellular space leading to
rupture of cerebral veins.
Questions:
2) The goal rate of correction for a patient with a
serum sodium of 165 mEq/L who is
hemodynamically stable is:
A)
B)
C)
D)
As quickly as possible
0.01 mEq/hour
0.5 mEq/hour
2 mEq/hour
Questions:
The correct answer is C. This is a straight forward
knowledge question, requiring the learner to recall the
goal rate of sodium correction in a patient with
hypernatremia who is hemodynamically stable.
Questions:
3) A 3 year old is admitted with gastroenteritis and
dehydration. His serum sodium is 167 mEq/L.
Once he is hemodynamically stable, fluid
management should be focused on providing:
A) Glucose
B) Free water
C) Sodium
D) Potassium
E) Chloride
Questions:
B is the correct answer. Hypernatremia is a total body free
water deficit rather than an excess of sodium.
Questions:
4) All of the following are possible etiologies for
hyponatremia EXCEPT:
A) Dilute formula feeding
B) SIADH
C) Diabetes insipidus
D) Non-osmotic release of ADH secondary to
acute illness
Questions:
C is the correct answer. Diabetes insipidus leads to
hypernatremia.
Questions:
5) A 2 year old patient with central diabetes
insipidus is admitted with a sodium of 170 mEq/L.
The labs findings most consistent with his
diagnosis are:
A) Elevated serum osmolarity and concentrated
urine
B) Decreased serum osmolarity and dilute urine
C) Decreased serum osmolarity and
concentrated urine
D) Elevated serum osmolarity and dilute urine
Questions:
D is the correct answer. Central diabetes insipidus leads
to decreased ADH production. This leads to an inability to
concentrate urine and an increase in serum osmolarity,
hypernatremia and dilute urine.
Questions:
6) A 4 month old has been receiving improperly
mixed formula with 1 scoop per 4 oz of water. She
presents with generalized tonic-clonic seizure and
a serum sodium of 118 mEq/L. The appropriate
fluid to use for immediate management of her
hyponatremia is:
A) Normal saline
B) 1/2 Normal saline
C) 3% Hypertonic saline
D) None-fluid restrict due to concern for SIADH
Questions:
C is the correct answer. This is a straightforward knowledge
question requiring learners to recall that symptomatic
hyponatremia is an emergency requiring prompt treatment with
hypertonic saline.