lecture 50 - Hypernatremia

Question 1

What is the most influential drier behind ADH secretion?

Answer 1

Hypovolemia&raquo_space; Hyperosmolarity

Question 2

defense of ECF Volume

how is volume sensed?

3 Players involved

Answer 2

Baro-receptors of the atrium and carotid sinus

Catecholamines – increase Na reabsorption

RAS –

ADH

Question 3

defense of Osmolality

how is osmolality detected?

2 Players in the defense of osmolality

Answer 3

anterior hypothalamus (SON)

Central Axis – thirst

ADH -

Question 4

where is ADH made?

where is it stored ?

Answer 4

Synthesis: made in the SON and PVN

Stored: Posterior Pituitary

Question 5

Non osmotic regulators of ADH

Answer 5

Nausea, Post operative pain, pregnancy

Question 6

Hypovolemic Hypernatremia -

describe the scenario-

How do you differentiate between renal vs non renal losses of H2O?

Answer 6

scenario: Patient has lost Na, but has lost even more Water;

The patient is dehydrated and Intravascular volume depleted

UNa –
If the kidney is working appropriately, in the setting of hypovolemia, it should be reabsorbing Na and H2O

Renal Losses: UNa > 20

Non Renal: UNa < 20

Question 7

Causes of Non Renal Losses leading to Hypovolemic Hypernatremia

Answer 7

® Excessive sweating, burns, fevers, diarrhea, fistulas

Question 8

Causes of Renal Losses leading to Hypovolemic Hypernatremia

Answer 8

Diurectics, Intrinsic renal disease

Question 9

○ Euvolemic Hypernatremia

describe the scenario:

what will be the Una

Answer 9

Loss of water with normal Body Sodium;

U NA will be variable

Question 10

○ Euvolemic Hypernatremia

• renal losses
• extra renal losses

Answer 10

Renal Losses: Nephrogenic DI (kidney unable to respond to ADH)

Extra renal losses: 
Insensible losses (water vapor loss through skin and breath) 

Hypodipsia

Central DI

Question 11

HyperVolemic Hypernatremia

describe the scenario

causes:

Answer 11

Excess Na in the setting of normal or only slight gain of water

Hypertonic Infusion – Normal Saline or Na Bicarb

Hypertonic Dialysis

Patient is eating a lot of salt tablets

Question 12

Patients at risk for developing hypernatremia

Answer 12

Inability to respond to sense of thirst — CNS Lesions (CVA or Tumor)

Physically unable to respond and get water – Obtunded, Intubated, Infant

Question 13

Clinical manifestations of Hypernatremia

Answer 13

Change in mentation – slight confusion to an overt coma

§ Metabolic encephalopathy —

(pt should have an absence of a new focal or lateralizing neurologic sign)

Question 14

• Treatment of Hypernatremia –
—- acute setting

time frame?
what is the body doing?
- what is the treatment?

Answer 14

acute setting (<24 hours)

body attempts to even out the tonicity of the environments of the intra and extra cellular spaces by pumping the cells full of electrolytes; but this is perturbing to the CNS

Treatment: Rehydrate the patient

Question 15

• Treatment of Hypernatremia –
—- acute setting

time frame?
what is the body doing?
- what is the treatment?

Answer 15

> 24 hours

the body extrudes perturbing electrolytes and replaces them with Idiogenic Osmoles (Betaine, phosphorycholine, sorbitol, myoinositol)

Treatment: slow hydration so as not to induce cerebral edema

Question 16

what are the idiogenic Osmoles

Answer 16

(Betaine, phosphorycholine, sorbitol, myoinositol)

Question 17

how do you calculate the amount of water to rehydrate with in the setting of acute hypernatremia ?

Answer 17

Calculate the electrolyte free water deficit

.6 x Weight in Kg) x ((Plasma Na - 140)/140