S4 L2 Hypo and Hypernatreamia Flashcards
Hypernatraemia:
- More of less common than hyponatraemia?
- What does measuring plasma Na+ actually mean?
- Causes of hypernatremia?
Hyponatremia:
- Common?
- Symptoms
- Causes
- Conditions associated with it
• Low Sodium very common in hospital patients
(• Serum CONCENTRATION of Na lower than 130/135mmol\L)
- Usually due to an increase in water/error in water balance
• Estimated to effect 10% of patients in hospital. Associated mortality of up to 20%
Symptoms:
• Correlates to severity and rate of onset.
• Neurological: agitation, nausea, focal neurology, coma. (Focal neurology - problem with nerves, spinal cord, brain, usually affecting a specific area, e.g. arm movement, leg movement)
How do you approach a patient with low Na+?
- What do you look at?
- Work out there plasma osmolality
The reference range of serum osmolality is 275–295 mosm/kg
(mmol/kg).
• Calculated osmolarity = 2 Na + Glucose + Urea (all in mmol/L). (2 as Na+ and Cl-)
If a patient is hyperglycaemic (i.e. high glucose), this will impact serum osmolality!
How to approach a patient with low Na+?
- If hypo-osmotic, what should you do now?
Fliod assessment, are they fluid depleted or odenmatous?
What to do with a patient with low Na+?
- If fluid depleted?
- — 2 groups…
Renal loss
Non-renal loss e.g.:
• GI losses
- Vomiting, Diarrhea, fistulas, pancreatitis
• Excessive sweating
• Third spacing of fluids
- ascites, peritonitis, pancreatitis, and burns
• Cerebral salt-wasting syndrome
- traumatic brain injury, aneurysmal subarachnoid hemorrhage, and intracranial
surgery
• Must distinguish from SIADH
What to do with a patient with low Na+?
- If ECF is normal - what possible causes?
Treatment of Hyponatreamia
Dilutational hyponatremia:
- E.g. cause
- An aside - name two major fluid compartments and their primary ions
- Which tissue/organ at most risk?
Run lung distance e.g. marathon, consumed a large amount of Na+ free fluid and diluting her Na+ stores. However, the body compartments are in osmotic equilibrium, so both the ICF and ECF have a lower osmolality
The major fluid compartments are the ICF and ECF:
- The primary ICF ion is K+
- The major ECF ions are Na+ and Cl
The brain. All cells in the Laur • en’s body swell as a result of excess water
ingestion. The brain is encased in a rigid skull
• The bony skull restricts the swelling of brain tissue, causing neurological
symptoms, including confusion, headache, loss of coordination. With
lower Na+ concentration, death can result
GW:
- Addison’s disease: Hormone levels?
- What is ‘urine specific gravity’?
- Where does aldosterone act in the kidney?
- For hyponatreamia - what do you need to decide?
- SIADH - how does this affect serum Na+ levels?
Addison’s: Low cortisol and low aldosterone
Urine specific gravity: Provides a measure of the concentration of solutes in the urine. Measure of the ratio of urine density compared to water. Normal is 1.01-1.025, 1.000 is pure water
Aldosterone acts on: EnaC (in DCT and collecting duct) and ROMK (in DCT and collecting duct)
Hyponatreamia: Need to decide if it is true hyponatreamia or dilutional hyponatreamia
SIADH: More ADH = upregulation of aquaporins = more fluid retained = dilutional hyponatreamia
GW cont.:
- Potentially, if a patient is in heart failure, what is wrinkley ankles a sign of?
- Where does Spirnolactone and Furosemide act on? (which channels in the nephron?)
- How does vomitting affect K+ levels?
- How does AKI affect K+ levels?
- What is a sign that you’ve given a patient too much fluid? (1st sign?)
Wrinkly ankles: Sign of dehydration (as if in heart failure - normally has peripheral oedema)
Spirnolactone: ENaC is inhibited
Furosemide: Na+/K+/2Cl- is inhibited
Vomitting: decreases serum K+
AKI: increases serum K+
Too much fluid: Pulmonary oedema (crackles on the lungs), always affects the lungs first (I’m not sure why)
