Hypernatremia and hyponatremia

Question 1

What is the classification of hypernatremia

Answer 1

> 145 mM

Question 2

Underlying physiology causes of hypernatremia

Answer 2

High sodium intake

Loss of fluid volume (more water)
- sweating/dehydration/diarrhea

Low levels of ADH

Hyperaldosteronism

Diabetes insipidus (Central and nephrogenic)

Hypothalamic lesions

Osmotic diuresis
- use of mannitol, high protein time feedings, glucose in uncontrolled diabetes

Severe exercise or seizures

measured plasma Na+ concentration does not always imply hyper or hyponatremia! NEED to determine sodium concentration with respect to total volume present

Question 3

Common Symptoms of hypernatremia

Answer 3

AMS

Lethargy

Seizures

Extreme thirst

Muscle twitching/spasms

Question 4

What are the percentages to use when estimating total body water?

Answer 4

50% females

60% males

Question 5

Treatments for hypernatremia

Answer 5

1 is IV fluids or oral replacement with water

Desmopressin next line usually

Question 6

What are common IV solutions?

Answer 6

Hypertonic = 3% normal saline

Isotonic = 0.9% normal saline or ringers

Hypotonic use this for hypernatremia

• 0.45% normal saline
• D5W (5% dextrose in water)

Question 7

What is the diagnostic value of hyponatremia?

Answer 7

Na <135mM

Question 8

Etiologies of hyponatremia

Answer 8

Very large amount of etiologies

**Very common in hospitalized patients (22%)

Low sodium or excessive water intake

Increased effects of vasopressin in clincial use

Question 9

Clinical symptoms of hyponatremia

Answer 9

Nausea/headache

vomiting

AMS

Abdominal Cramping or distal leg cramping

• • if sodium dips below <120mM**
• seizures
• coma
• brainstem herniation
• death

Question 10

Acute vs chronic hyponatremia

Answer 10

Acute:

• <48hrs
• much more serious
• often iatrogenic (hospital cause or inappropriate use of hypotonic fluids/vasopressin)

Chronic:

• > 48hrs
• less serious but still important
• usually a cause of physiological correction attempts but doesn’t work properly

Question 11

Common causes of acute hyponatremia

Answer 11

Post up iatrogenic fluids/VP

Post-op/ pre-op iatrogenic glycine irrigation

Colonoscopy prep improperly

Premenopausal women

Recent/improper use of thiazides

Polydipsia

MDMA use

Extreme exercise without water replacement

Question 12

Osmotic demyelination syndrome (ODS)

“Central pontine myelinolysis*

Answer 12

Usually due to a patient who is originally hyponatremic and is corrected way to fast
- damages the pons most

Results in fluctuating ECF/ICF volumes and neuronal damage

Symptoms: “acute onset of all”

• confusion
• delirium
• hallucinations
• dysphagia
• inability to balance properly
• slurred speech
• tremors

Question 13

Causes of hyponatremia where the patient is euvolemic

Answer 13

Glucocorticoid deficency

Untreated Hypothyroidism

Stress

Drugs

SIADH

Question 14

Tests to do when you have a hyponatremic patient

Answer 14

Plasma osmolatility

Urine sodium and urine overall osmolality

plasma glucose level
- if Patient has high glucose (add 1.6-2.4 mM to total sodium concentration for every 100mg/dl above normal)

Question 15

Pseudohyponatremia

Answer 15

Increases or normal calculated serum osmolality in the presence of hyponatremia

this is usually the cause of extreme proteins and lipid levels in the plasma compared to sodium

true hyponatremia shows low plasma osmolality and low sodium levels

Question 16

Methods of correct of hyponatremia

Answer 16

Restriction of water
- primary therapy in patients with edema, SIADH, primary polydipsia and advanced renal failure

Sodium chloride isotonic saline administration (also increased dietary salt)

• primary therapy in patients with true volume depletion or in adrenal insufficiency
• CANT use in edematous patients

Hypertonic saline = only acute symptomatic hyponatremia