Sodium Disorders

Question 1

When does Hypernatremia occur?

Answer 1

With loss of free water
-Sweating, burns, fever, Pneumonia, Diarrhea, Diuretics

Question 2

What is Diabetes Insipidus (DI)?

Answer 2

High-volume water loss from insufficient or ineffective ADH

Question 3

What causes Central Diabetes Insipidus (DI)?

Answer 3

Any CNS disorder or damage to the production of ADH in the Hypothalamus or storage in the posterior pituitary

Question 4

What is Nephrogenic Diabetes Insipidus (NDI)?

Answer 4

Loss of ADH effect on the collecting duct of the kidney

Question 5

What are common causes of Nephrogenic Diabetes Insipidus (NDI)?

Answer 5

Lithium, Demeclocycline, CKD, Hypokalemia, Hypercalcemia

Question 6

What are common symptoms of Hypernatremia?

Answer 6

Neurological symptoms: confusion, disorientation, lethargy and seizures

If uncorrected it can lead to coma and irreversible brain damage

Question 7

What is High Serum Sodium nearly equivalent to?

Answer 7

Hyperosmolality: causing fluid loss from the skin, kidneys or stool
-Decrease urine volume (high urine volume in DI)
-Increased Urine Osmolality (high Uosm in DI)
-Decreased urine sodium

Question 8

What is the best initial test for DI?

Answer 8

Water deprivation test: with DI urine volume stays high and Uosm stays low despite high urine production and developing dehydration

Question 9

How to distinguish Central and Nephrogenic DI?

Answer 9

ADH levels and response

Question 10

What are the ADH level in CDI?

Answer 10

ADH is low

Question 11

What is the ADH level in NDI?

Answer 11

Elevated

Question 12

How does CDI respond to ADH administration?

Answer 12

Sharp decrease in urine volume and increase in Osmolality

Question 13

How does NDI respond to ADH administration?

Answer 13

No change in urine volume or osmolality

Question 14

What does a Urine Osmolarity <800 in Hypernatremia suggest?

Answer 14

Renal water loss

Question 15

What are subtypes of Renal water loss for Hypernatremia?

Answer 15

Osmotic Diuresis and Diabetes Insipidus

Question 16

What are common causes of Osmotic Diuresis?

Answer 16

Glucose: DKA/HHS

Urea

Mannitol

Question 17

What does Urine Osmolarity >800 in Hypernatremia suggest?

Answer 17

GI water loss, insensible water loss or increased sodium intake

Question 18

How do you treat Hypernatremia?

Answer 18

Correct the underlying cause of fluid loss

CDI: replace ADH (DDAVP)

NDI: Correct electrolytes, stop offending drugs, give thiazide or NSAIDS

Question 19

What happens if you bring Na levels down too quickly?

Answer 19

Cerebral edema: fluid shifts from vascular space into brain cells leading to worsening confusion and seizures

Question 20

How is Hyponatremia characterized?

Answer 20

Overall volume status of the body

Question 21

What are the most common causes of Hyponatremia with a Hypervolemic state?

Answer 21

CHF, Nephrotic Syndrome, Cirrhosis

Question 22

What causes Hyponatremia with a Hypervolemic state?

Answer 22

Intravascular volume depletion leads to increased ADH: pressure receptors in atria and carotids sense decreased volume and stimulate ADH production and release: Na drops but vascular volume is maintained for organ perfusion

Question 23

What are the most common causes of Hyponatremia with a Hypovolemic state?

Answer 23

Sweating, burns , fever, pneumonia (insensible loss), Diarrhea and Diuretics

Question 24

How do the causes of Hyponatremia with Hypovolemia occur?

Answer 24

A little Na and a lot of H2O are lost in urine which is replaced with free water that doesn’t have Na: overtime this depletes the body of Na and the Serum Na level drops

Question 25

What are the most common causes of Hyponatremia with Euvolemia?

Answer 25

Pseudohyponatremia (Hyperglycemia) Psychogenic Polydipsia Hypothyroidism Syndrome of Inappropriate ADH Release (SIADH)

Question 26

How does Hyperglycemia lead to Hyponatremia?

Answer 26

Hyperglycemia acts as an osmotic draw on fluid inside the cells: free H2O leaves cells to correct the hyperosmolar serum dropping the sodium level

Question 27

How much does Na drop for every 100 above normal Glucose is?

Answer 27

1.6

Question 28

What is Psychogenic Polydipsia?

Answer 28

Massive free water ingestion above 12-24 liters a day overwhelms the kidney's ability to excrete water

Question 29

How does Hypothyroidism lead to Hyponatremia?

Answer 29

Thyroid Hormone is needed to excrete water: low thyroid hormone decreases free water excretion

Question 30

What are common Causes of SIADH?

Answer 30

SSRI, Sulfonylureas, Vincristine, Cyclophosphamide,TCA Small-cell lung cancer Pain

Question 31

How does Hyponatremia present?

Answer 31

Entirely with CNS Symptoms: Confusion, lethargy, disorientation, seizures, coma

Question 32

What is the Expected Urine Osmolality with Hyponatremia?

Answer 32

Low <100

Question 33

What is the Urine Osmolality in SIADH?

Answer 33

High

Question 34

What is the expected Urine Sodium in Hyponatremia?

Answer 34

Low <20

Question 35

What is the Urine Sodium in Hyponatremia?

Answer 35

High >40

Question 36

What are common treatment options for Hyponatremia?

Answer 36

ADH Antagonists Demeclocycline

Question 37

What ADH antagonists are used for Hyponatremia?

Answer 37

Tolvaptan and Conivaptan: only for urgent treatment in the hospital

Question 38

How does Demeclocycline work?

Answer 38

Treats Chronic SIADH by blocking the action of ADH at the collecting duct of the kidney tubule

Question 39

How quickly must you correct Na in Hyponatremia?

Answer 39

<0.5-1mEq per hour or <12-24mEq per day

Question 40

What is a complication of correcting Hyponatremia too rapidly?

Answer 40

Osmotic Demyelination: Central Pontine Myelinolysis

Question 41

How does Osmotic Demyelination present?

Answer 41

Dysarthria Dysphagia Paraparesis or Quadriparesis "Locked-In": like you lost your entire brainstem