Your SlideShare is downloading. ×
Electrolyte Free Water Clearance
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Introducing the official SlideShare app

Stunning, full-screen experience for iPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Electrolyte Free Water Clearance

16,942
views

Published on

this is an 18 slide subset of the way too long lecture on sodium called Hyponatremia Dreadnaught

this is an 18 slide subset of the way too long lecture on sodium called Hyponatremia Dreadnaught


0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
16,942
On Slideshare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
280
Comments
0
Likes
3
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. True hyponatremia
    • Hyponatremia occurs when water intake exceeds water excretion.
  • 2. True hyponatremia
    • Hyponatremia does not occur when sodium excretion exceeds sodium intake.
    Negative salt balance causes hypovolemia
  • 3.
    • If a person drinks more water than the kidney is capable of clearing the excess water will dilute the plasma.
    Causes of hyponatremia: Increased intake
    • To exceed the maximal renal clearance of water an adult needs to drink about 18 liters a day.
    clearing
  • 4. Water clearance
    • Clearance as a general concept:
      • The clearance of any substance is the volume of blood cleared of that substance in a set unit of time.
    • Water clearance
      • Total water clearance is equal to urine output. Not a useful concept.
  • 5. Free water clearance and soup
    • Imagine urine divided into two components
      • A solute component containing all of the solute at the same osmolality as plasma.
        • Loss of this component does not change plasma osmolality
        • Ladle of soup
      • A free water component providing the balance of the volume.
        • Loss of this solute free water will change serum osmolality.
        • Boiling off water from soup
    In regards to sodium all that matters is the free water component
  • 6. Free water clearance 0.5 liter free water Solute component (plasma osmolality 284 mOsm/kg) Use clearance to calculate the osmolar clearance 1 liter 142 mOsm/Kg 0.5 liter 284 mOsm/Kg
  • 7. Free water clearance Solute component (Solute Clearance) ? 0.5 liter Zero mOsm/Kg Free water component (Free water Clearance) The free water component equals urine volume minus the solute component 1 liter 142 mOsm/Kg 0.5 liter 284 mOsm/Kg
  • 8. Free water clearance 0.5 liter 568 mOsm/Kg 1 liter 284 mOsm/Kg -0.5 liter 568 mOsm/Kg
  • 9. Free water clearance Solute component (plasma osmolality 284 mOsm/kg) Use clearance to calculate the osmolar clearance 1 liter 284 mOsm/Kg 0.5 liter 568 mOsm/Kg
  • 10. Free water clearance Solute component (Solute Clearance) ? Free water component (Free water Clearance) 0.5 liter 568 mOsm/Kg – 0.5 liter Zero mOsm/Kg 1 liter 284 mOsm/Kg
  • 11. Free water clearance: Implications Dilute urine increases serum osmolality Concentrated urine de-creases serum osmolality Dilute urine Solute free water Concentrated urine Negative free water Na + Na +
  • 12. Free water clearance: The math
  • 13. Free water clearance: Math Examples
  • 14. Electrolyte free water clearance
    • Osmolality doesn’t cause problems, rather tonicity causes changes in cell volume which cause clinical syndromes.
    • So free water clearance must be refined to measure clinically significant changes in tonicity.
  • 15. Electrolyte free water clearance
    • Osmotically active particles (those that contribute to tonicity):
      • Sodium
      • Potassium
      • Albumin, calcium and others
    • Sodium is the dominant osmotically active solute of serum to the point that others can be ignored.
    • Urine has a significant potassium content so in urine sodium and potassium are equal partners in determining urinary tonicity.
  • 16. Electrolyte free water clearance
    • Convert the free water clearance calculation to electrolyte free water clearance
      • Substitute urine osmolality with the sum urine Na + K
      • Substitute serum osmolality with serum sodium
    Free water clearance Electrolyte free water clearance
  • 17. Electrolyte free water clearance: CHF vs. SIADH
    • Heart Failure
      • Urine Osmolality: 800
      • Serum Osmolality: 270
      • Urine Volume: 800
      • Urine Na: 5
      • Urine K: 40
      • Serum Na: 125
    • SIADH
      • Urine Osmolality: 800
      • Serum Osmolality: 270
      • Urine Volume: 800
      • Urine Na: 125
      • Urine K: 40
      • Serum Na: 125
  • 18. Etiology of hyponatremia
    • Hyponatremia occurs when water intake exceeds water excretion.
    • Hyponatremia occurs when water intake exceeds electrolyte free water clearance.
    Ingestion > EFW clearance