Paul m. shaniuk, md, pgy-4July, 2015

University hospitals case medical centerWade park va medical center

Intern BootcampElectrolyte Management:

Disorders of Serum Sodium

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?

Beer PotomaniaSIADHCirrhosisPancreatitisSurreptitious Diuretic

UseRenal lossesGI losses

Glucocorticoid Deficiency

HypothyroidismDrug useAcute or Chronic

Kidney failureThird spacing of

fluidsType 2 RTADKAOsmotic 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?