Intern Bootcamp
Electrolyte Management:
Disorders of Serum Sodium
PAUL M. SHANIUK, MD, PGY-4
JULY, 2015
UNIVERSITY HOSPITALS CASE MEDICAL CENTER
WADE PARK VA MEDICAL CENTER
Remember me?
This is not a simple topic!
Nobody Dies!
Electrolyte Basics
Objectives
 Categorize the differential diagnosis for disorders of
sodium balance
 Discuss approach to disorders of sodium balance
 Acute Management of Hyponatremia
 Acute Management of Hypernatremia
 If time, an interlude on potassium & magnesium
Case 1
 55 year old male with no significant PMHx except for
known chronic alcoholism for 30 years (6 pack of
beers daily and a 5th of vodka) who presents with
recurrent falls for the past 2 months. His daughter
took him to the doctor where his vital signs were
stable (HR 74 and BP 116/74), and got the following
labs
BMP 125/4.1/87/28/6/0.64<102. CXR & UA
negative. He was admitted for further work-up.
Case 1 Continued
 No significant family, medical or social history
except for alcoholism. Only medication is celexa that
he started 2 months ago.
 How do we work up his hyponatremia?
Differential Diagnosis?
 Glucocorticoid
 Beer Potomania
 SIADH

 Cirrhosis

 Pancreatitis

 Surreptitious Diuretic
Use
 Renal losses
 GI losses




Deficiency
Hypothyroidism
Drug use
Acute or Chronic Kidney
failure
Third spacing of fluids
Type 2 RTA
DKA
Osmotic diuresis
Classification of Hyponatremia
 Classify based on physical examination and the
patient’s volume status
Key Concept
 “A key concept in sodium disorders is that the
absolute plasma Na+ concentration tells one
nothing about the volume status of a specific
patient.”

Harrison’s Principles of Medicine, 18th Edition
Working Up Hyponatremia
 Hypovolemic, Euvolemic, Hypervolemic?
 Based on History & Physical
 Ratio of Total Body Water to Total Body Sodium
 Based on Serum & Urine Osmolarity
 Is the body responding appropriately or
inappropriately?

Based on Urine Electrolytes
Case Continued
 Physical exam showed a pale man who was A&Ox3
and in no distress. Normal cardiac, respiratory and
abdominal exam. JVP not elevated
 Neurologic exam showed b/l nystagmus with lateral
gaze and impaired b/l proprioception in the lower
extremities
 Skin exam with normal turgor and multiple
ecchymoses on his body.
Any other labs???
 Serum osmolarity – 244
 Urine osmolarity – 600
 Urine sodium - 166
How to Classify his Hyponatremia
 Hypovolemic, Euvolemic or Hypervolemic?
 Euvolemic based on physical exam
 Ratio of Total Body Water to Total Body Sodium?
 Excess of free water, based on low serum osmolarity
 Is the body responding appropriately or
inappropriately?

Inappropriately (urine osm & urine sodium elevated)
SIADH Criteria
Case Conclusion
 The patient was diagnosed with SIADH, most likely
deemed to be due to his celexa.
 Picture was clouded by the fact that he was
presumed to have baseline hyponatremia due to
alcohol use, but clinical picture did not fit beer
potomania (Urine Osm/Na would be low)
 Patient improved with 1.5 L a day fluid restriction &
holding celexa
Case 2
 46 y/o otherwise healthy male daycare worker who presents
with severe nausea, vomiting and diarrhea for 3 days. Recent
outbreak of rotavirus at his daycare who presents to the ED
with orthostatic dizziness
 No significant PMHx, Family or Social Hx, No medications or
allergies
 Vital signs are 37.7, HR 105, BP 108/64 (falls to 90/50 with
standing and HR increases to 128), RR 16, O2 sats
 Physical exam reveals dry mucus membranes, decreased skin
turgor, mild tachycardia, otherwise normal.
Case 2 Continued
 127/3.1/101/15/35/1.1<70
 Serum Osm 320, Urine Osm 750, Urine Na 10
How to Classify Hyponatremia
 Hypovolemic, Euvolemic or Hypervolemic?
 Hypovolemic
 Ratio of Total Body Water to Total Body Sodium?
 Both decreased (both dehydrated and hyponatremic
2/2 GI losses and poor PO intake)
 Is the body responding appropriately or
inappropriately?

Appropriately (urine osm elevated with low urine
sodium indicating kidneys are retaining both fluid &
sodium)
Management?
 He needs both water & sodium = IV fluids
 What fluids do we give him?
 0.45% NS? (72mM Na+)
 0.9% NS? (154 mM Na+)
 3% NS? (513 mM Na+)
 Bolus or Proceed slowly?
Important Concepts with Fluid Replacement in
Acute Hypovolemic Hyponatremia
 Calculate volume deficit and sodium deficit, usually
with the assistance of an online calculator.
 Replete SLOWLY. (Goal to increase by 4-6 mEq/L in
a 24 hr period. No more quickly than 10mEq!)
 Monitor! Check RFP Q6H-Q8H especially in the first
24.
Important Caveat #1
 If in shock, BOLUS FIRST with isotonic saline, ask
questions later
Important Caveat #2
 If the patient is encephalopathic or seizing, admit
to MICU for 3% hypertonic saline (increase by 4-6
mEq in the first 6 hrs… do not reach
normonatremia in the first 48 hrs)
Important Caveat #3
 As you correct the volume deficit, intrinsic
ADH secretion decreases and thus patient
will start to autodiurese and you can
overcorrect easily
Case 2 Continued
 The patient was deemed to not be in shock and was
not having seizures/encephalopathy, so was started
on IV normal saline at 250cc/hr (calculated to
increase serum sodium by 5 mEq in 24 hrs) and
admitted to the ward
 RFP slowly incremented, patients sodium increased
back to normal over 3 days.
 Patient discharged home, quit his job and now works
at the CDC.
What NOT to do
What about Hypervolemic Hyponatremia?
 Principles are similar
 Can try vaptans (vasopressin antagonists), especially
in heart failure or cirrhosis
 If you are giving a patient tolvaptan, the patient must
be allowed to drink free water ad lib, or else could
over-correct his serum sodium
Case 3
 A 90 y/o female with advanced dementia is brought
to the ED by her children with failure to thrive. She
is non-verbal and had been having difficulty
swallowing clear liquids and solid foods for the past
few months. Family has been noting that she appears
more confused and having very dark urine.
 In the ED, vitals were 37.2, HR 110, BP 90/60, RR
14, O2 sats 93% on RA
Case 3 Continued
 Physical exam shows a frail, elderly female who is
responsive only to painful stimuli and loud voice, but
does open her eyes to this. A&Ox1.
 Dry, cracked mucus membranes, severely decreased
skin turgor, incontinent of dark urine, stage 2 sacral
decubitus ulcer present on admission
Case 3 Continued
Labs in the ED are pertinent for the following:
 RFP 161/4.6/129/22/45/2.2 (baseline 1.4) <80
 ED said she was dehydrated and gave a bolus of 1L
normal saline, and admitted to Wearn.
 Serum Osm 330, Urine Osm 850, Urine sodium 20
Basics on Hypernatremia
 Less common than hyponatremia
 Associated with high mortality (some studies suggest 40-
60%)
 Due to combined water & electrolyte deficit, but loss of
free water exceeds the loss of electrolytes. (Hypertonic)
 Most common in patients with decreased thirst AND
decreased access to fluids

Hypernatremia is a powerful thirst stimulant
Working up Hypernatremia
 Also based on physical exam (typically though
hypovolemia is seen)
 Is the urine concentrated?
 If Yes – likely 2/2 free water deficit from insensible, GI or
renal losses

If No – likely 2/2 diuretics or diabetes insidipidus (either
central or nephrogenic)
Management of Hypernatremia
 Estimate Total body water: (50% of body weight in
women and 60% in men)
 Calculate Free Water Deficit [(Na -140)/140] x TBW

Or use a handy calculator
 Replete the free water deficit over 48-72 hrs without
increasing the plasma sodium by > 10 mM in a 24 hr
period
 Don’t forget about potential for ongoing water losses
from either diarrhea, diuresis or insensible losses!
Case 3 Continued
 The patient was started on normal saline in the ED at
100 cc/hr and admitted to the floor
 Upon arrival to the floor, repeat RFP shows a sodium
of 162.
 You calculate a free water deficit of 3.9L
Case Conclusion
 You start the patient on D5W infusion at 65 cc/hr
and monitor RFPs Q8H.
 Her deficit improves appropriately over 72 hrs as
does her mental status
 Speech therapy finds that the patient has severe
dysphagia. After extensive discussion, family opts for
feeding orally for pleasure; they do not want a PEG.
Patient made DNR and discharged to SNF near the
oldest daughter’s home.
Key Concepts with Hypernatremia
 Associated with high mortality!
 In patients with hx of head trauma, brain surgery or pituitary
resection, can represent DI/panhypopituitarism
 If in shock, bolus with isotonic saline and correct
fluids status later
Key Concepts with Hypernatremia
 Enteral repletion is preferred if possible as there are
risks with free water infusions (if our patient had a
G-tube, free water flushes could have been given)
 Some attendings or RNs are uncomfortable with
D5W infusions outside the MICU. Realistically, any
form of hypotonic saline can be used (0.45% NS,
0.2% NS, etc)
Quick Word on Potassium repletion
 3 forms of oral potassium
 Tablet (horse pill)
 Oral packet
 Oral liquid
 IV potassium
 Central Line formulation (more concentrated)
 Peripheral line formulation (cannot give more than 20mEq
over 2 hrs, but can give x 2 doses to give 40mEq)
Quick word on Potassium Repletion
Replete orally if possible!
If 3.1-3.4 mEq/l -> Give 40mEq
If 2.6 – 3.0 mEq/l -> Give 60-80mEq
If < 2.5 -> Give 80-120mEq
Final word on Potassium Repletion
 Replete with caution in patients with AKI, ESRD, etc
 Don’t forget to account for ongoing losses!
 Such as diarrhea, diuresis, etc
Quick word on Magnesium repletion
 IV repletion is preferred
 Oral forms


Magnesium Chloride 64mg PO
Magnesium Oxide 400mg PO
 IV forms



If Mg 1.0-1.6 give 2mg IV over 2 hrs
If Mg < 1.0, give 4mg IV over 4 hrs
Some Endocrinologists would suggest that giving over a longer
duration (such as 12-24 hrs) may help prevent rapid shifts and may
overall increase effectiveness.
Remember your repletion goal
 If a-fib, or cardiac arrhythmia
 Goal K > 4.0, Mg > 2.0
 If in torsades, give IV Mg
 Otherwise, aim for physiologic levels
References
 Harrison’s 18th Edition
 Braun et al. Diagnosis and Management of Sodium
Disorders: Hyponatremia and Hypernatremia Am Fam
Physician 2015 Mar 1;91(5):299-307.
 Verbalis, Et Al. Diagnosis, Evaluation, and Treatment of
Hyponatremia: Expert Panel Recommendations The
American Journal of Medicine (2013) 126, S1-S42
 Pocket Medicine Fourth Edition. Edited by Marc S.
Sabatine
Questions?