Hypo- and Hyper- natraemia Flashcards
Sodium is at a much higher concentration in the extra cellular compartment (T/F)
True
Sodium follows water (T/F)
False
-water follows sodium
What are the signs of reduced extracellular fluid volume?
Low volume, Concentrated urine Dry mucosa increased pulse rate Decreased skin turgor Loss of conciuosness
Name a sign of increased interstitial fluid levels:
Pitting oedema
What system controls the sodium homeostasis?
RAAS
-renin angiotensin aldosteron system
What is the main hormone responsible for sodium retention by the kidneys?
Aldosterone
-a mineralocorticoid
What is the function of ADH (anti diuretic hormone) on the renal tubules?
Causes water reabsorption
What is countercurrent multiplication?
- Descending loop of Henle lets water out
- Ascending loop of henle lets sodium out, without water following
- Thus, osmolality down descending loop increases (water out) and osmolality up ascending loop decreases (salt out)
(see link slide 21,2MB-NA-2017.pptx)
What are the common mechanisms of sodium loss?
- Adrenal/kidney malfunction
- loss from gut or skin (burns)
-Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH)
What can diabetes insipidus cause in terms of sodium balance?
-increased H2O loss can cause hyoernatraemia
How is excess sodium, with normal water levels, treated?
Loop diuretics
Addison’s disease is a primary adrenal insufficiency. How does it affect water levels?
- Low corticosteroid production
- sodium is not retained in the kidneys
- sodium lost from ECF
- clinical dehydration
Oedema tends to arise when the effective circulating volume is too low. What hormones are secreted to cause this? How do they achieve this?
ADH
-promotes water retention
Aldosterone
-promotes sodium retention
Excess retained water ends up in interstitial fluid, causing oedema.
