Hypernatremia ☺️

Question 1

Presentation
Investigation findings
-dehydration => AKI
-pituitary issue?

Answer 1

Thirst
Lethargy
Neurological dysfunction (dehydration of brain cells)

Dehydration

• Na => high
• Urea => high
• Urine Na and osmolality => high (retaining water)

Low ADH

• Na => high
• Urea, creatinine => high (water cannot be retained)
• Urine Na and osmolality => low (ALD action)

Question 2

What regulates ECF volume

What happens when there is water loss

Answer 2

ECF volume regulated by Na

Loss of water

• greatest loss in ICF
• smaller loss in ECF (water moves out of the ICF => ECF before being lost)
• increased loss => concentration of plasma Na

Question 3

What is water balance controlled by

What factors influence ADH secretion

Answer 3

ADH

Affected by

• osmolality
• ECF volume
• stress/trauma
• drugs

Question 4

Differential diagnosis algorithm for hypernatremia

• high urine volume => high/low urine osmolality
• low urine volume => non renal loss/decreased intake

Answer 4

High urine volume and osmolality
-hypertonic Na solution
-osmotic diuresis
High urine volume and low urine osmolality
-central/peripheral DI
THESE ONLY LEAD TO HYPOVOLEMIA IF UNABLE TO INCREASE WATER INTAKE

Low urine volume
Non renal loss
-diarrhoea
-burns
-fever
-hyperventilation

Decreased intake of water

Question 5

How would you treat hypernatremia

• normovolemic
• hypovolemic

Answer 5

Address Na

Hypovolemic
-PO/IV dextrose fluids

Normovolemic

• PO/IV dextrose fluids
• treat underlying cause
• Central DI => desmopressin
• Peripheral DI => thiazides (paradoxical effect)

Hypervolemic

• PO/IV dextrose
• treat underlying cause => Na restriction