Renal - 03 - Hypernatremia/hyponatremia

Front 1

hyponatremia is usually caused by what mech (in general)

Back 1

dilutional - conseqence of impaired free water excretion

Front 2

what is necessary for the kidney to excrete free H2O

Back 2

absence of ADH

intact diluting segment

delivery of filtrate to distal tubule

adequate number of nephrons

Front 3

hypernatremia is usually casued by (in general)

how can you correct it?

Back 3

deficit of water in intravascular space

to correct:
adequate H2O
appropriate secretion of ADH
tubular response to ADH

maintain medullary concentration:
intact ascending limb
urea availability
intact vasa rectae

Front 4

SIADH diagnostic features

Back 4

hypotonic serum osmolality and hyponatremia

urine is less than max dilute

urine sodium matches intake

absence of other causes of decreased free H2O

improvement after H2O restriction
__________

in SIADH - not volume depleted - you don't need ADH, but you are secreting it inappropriately - retains water, dilutes serum -> hyponatremia

note you don't get hypertension or edema because you're losing sodium still from the urine, but getting volume from water absorption

Front 5

treatment of SIADH

Back 5

water restriction

SIADH is a problem with handling of water loading - not solute loss

Front 6

decrease in serum Na+ can be caused by:

Back 6

water intoxication

decreased effective circulating volume
---w/ decreased extracellular volume -> hypovolumia
---w/ normal extracellular volume -> adrenal or thyroid insuffciency
---w/ increased extracullar volume -> hypervolemia

SIADH

Front 7

diabetes inspidus central vs nephrogenic

Back 7

central - can't make ADH (this means giving ADH will help)

nephrogenic - can't respond to ADH (this means giving ADH doesnt help)

Front 8

differentiating diabetes mellitus from diabetes insipidus

Back 8

[urine osm]/[serum osm]

in DM - get ratio > 1 (due to glucose in urine)

in DI - get ratio < 0.7 (free water diuresis)