L3- Hypernatremia Flashcards Preview

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Flashcards in L3- Hypernatremia Deck (13)
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1
Q

What are the 3 ways that Serum Na can be high?

A

Serum [Na] = Na/H2O = Sodium concentration = salt relative to water

Higher serum sodium concentration via 3 ways:

↓Na/↓↓↓ H2O - too much loss of water
↔Na/↓H2O = normal salt but loss of water
↑↑↑Na/↑H2O = exception to the rule!!! Rare where too much salt relative to increased water content

HYPERNATREMIA = DEHYDRATION!!!!! (too much water loss compared to salt)

Basically, can’t respond to sense of thirst or obtain water, too much salt or lack of ADH.

2
Q

How do you calculate Serum Osm?

A
3
Q

What is the value of Very Dilute urine w/ no ADH?

What is the value of very concentrated urine w/ high ADH?

A

Dilute - 50-100 mosms/kg

vs

1200 mosms/kg

4
Q

What are the steps in the algorith for hypernatremia?

What are common presentations?

A

High Posm or high Na then Use physical exam to figure out volume status

Most commonly presents w/ Hypovolemia or Euvolemia

5
Q

Hypovolemic hypernatremia:

What does it mean? Causes? Urinalysis?

A

Dehydrated AND volume depleted

Renal Causes: Diuretics or renal problems

Una >20 (should be less!)

Non-Renal Causes: Sweating, Burns, Fever, Diarrhea

Una <20

6
Q

Normovolemic Hypernatremia:

What does it mean? Causes? Urinalysis?

A

Loss of water but normal Na - Dehydrated but volume ok

Renal Causes: Nephrogenic DI - can’t respond to ADH

Extrarenal causes: Central DI - cant make ADH, or Hypodypsia, or insensitive losses in lungs and skin

UNA can vary

7
Q

Hypervolemic Hypernatremia:

What does it mean? Causes? Urinalysis?

A

RARE- Exception to the rule bc most about dehydration but this is excess Na intake

Causes - Eat Salt tablets or Infusion Hypertonic

Una >20 bc volume expanded

8
Q

clinical manifestations of hypernatremia?

A

Increased muscle irritability

*Change in mentation - confusion to coma signs range classified as **Metabolic Encephalopathy **

Acute and chronic adaptations to changes in cell volume

9
Q

What is the CNS defense to hypernatremia and how does that cause encephalopathy?

What are the treatments?

A

In response to high Na, cells shrink an dthen pump in electrolytes so water will follow back into cells and restore cell volume. The problem is that these electrolytes purturb neuronal functioning and lead to encephalopathy.

Acute Tx: Rapid hydration

Chronic Tx: Idiogenic Osmols to extrude perturbing electrolytes and replace them to maintain volume

- betain, sorbitol, phosphorylcholine, myoinositol

CAREFUL - slow correction otherwise Osmotic Demyelination Syndrome

1 mEq/L [Na]/hour

10
Q

Treatment of Hypernatremia?

A

HYDRATION!!!!

Calculate the Electrolyte free water deficit

Water deficit = .6 x weight (kg) x (plasma [Na] - 140)/140

ADH replacement for central DI or partial nephrogenic DI

Diuretic therapy for RARE patient w/ hypervolemic hypernatremia

11
Q

Volume depends on what?

Salt problems depend on what?

A

Volume depends on Na status

Salt problems - hypo or hypernatremia depend on WATER - hydraiton

12
Q

Wha tis normal serum [Na}?

A

140!!

13
Q

In Euvolemic Hypernatremia, what lab value is more helpful: Una or U-Osm?

A

Uosm more helpful bc patient is normovolemic

Uosm indicates if responding/releasing ADH or not

Uosm should be greater than Posm if responding to ADH