Renal Function Flashcards
Function of Kidney
Concentration of Urine
Reabsorption of Nutrients
Acid base and electrolyte balance
Excretion of waste
Blood pressure
Water reabsorption and concentration
Hormonal Regulation of Body Water
Anti-Diuretic Hormone (Vasopressin)
Regulates water reabsorption
Vasopressin Regulation
Increase ADH, increases water absorption
Decrease ADH, decreases water reabsorption
Disease state with Increase ADH
Inappropriate ADH secretion
Disease state with Decrease ADH
Diabetes insipidus
Osmolality Defintion
Concentration of solutes dissolved in a body’s water
Expressed in milliosmoles (mOsm)/kilogram of water
Osmolality Measure
Osmotic pressure across body membranes
Measure of the osmoles of solute or dissolved particles per kg
Osmometry
Term used for the analysis osmolality
Formula 1 for Osmolality
2.0(Na+) + (glucose/20) + (BUN/3)
Formula 2 for Osmolality
1.86(Na+) + (glucose/18) + (BUN/2.8) + 9
Osmolar Gap
Difference between the calculated and measures osmolalities
Urine Osmolarity 24 hr Collection
300-900 mOsm/kg
Urine Osmolarity Random
50-1200 mOsm/kg
Urine to Serum Ratio
1.0-3.0
Serum Osmolarity
275-295 mOsm/kg
Osmolar Gap
5-10 mOsm/kg
Principles of ABG Measurement
Freezing Point Decrease
Vapor Pressure Decrease
Boiling Point Increase
Osmotic Pressure Increase
Freezing Point Osmometry
Determined super-cooling the sample below the freezing point
- Initiated by physical shock or very cold stir wire
- Water-ice mixture produced which remains at freezing point plateau long enough for temperature to be measured
- Uses a 2 point calibration against salt solutions
Vapor Pressure Osmometry
Changes in concentration of solutes are accompanied by linear and proportional chances in properties
- Vapor pressure is a force exerted by the gaseous phase of a two phase system
- The pressure of the vapor that is formed above its liquid is called the vapor pressure
Common Increases to Osmolar Gap
> 10 mOsm/kg
Mannitol
Glycine
Methanol
Ethylene glycol
Higher the gap, the worse the prognosis