Topic 1.73 - Hypotonicity: pathogenesis and consequences

What are 9 possible causes of hypotonicity?

Water poisoning

Moderate water intake in renal failure

Syndrome of inappropriate ADH

Severe edema

Salt deprivation

Sweating and drinking just water

Addison's disease

Renal tubular acidosis IV

Cystic fibrosis

Why is there hypoosmolarity in salt deprivation?

Hypoosmolarity because the level of salt in the ECS is decreased

Why does hypoosmolarity develop if you just drink water when sweating?

Hypoosmolar fluid containing a lot of water and little salt is lost -> hypertonicity - however, drinking just water to rehydrate -> hypotonicity

How does the body compensate for hypoosmolarity (3)?

Suppresses ADH release

Increases aldosterone

Increased salt craving

What are consequences of hypoosmolarity (2)?

Non-specific inhibition of enzymes

-enzymes are dependent on a certain osmolarity to function properly

Cellular swelling

What can be the result of cellular swelling in the brain?

Increased intracranial pressure -> dizziness, headache, vomiting and potentially coma and herniation