Unit 7 - Renal Disease

Question 1

what is the “underfill” VS “overfill” hypothesis? which can be treated with loop diuretics?

Answer 1

glomerular disease causes…
U: increased filtration of plasma PRO
-tubular catabolism of albumin and albuminuria –> albuminemia –> reduced oncotic pressure –> edema
O: primary renal sodium retention –> plasma volume expansion –> increased capillary hydrostatic pressure –> edema

only OH can be treated with loop diuretics to diurese, b/c in UH will die of hypovolemia

Question 2

what are some problems caused by increased glomerular permeability?

Answer 2

• thromboembolism
• increased infections
• edema

Question 3

what are the actions of ADH? what happens if it’s removed?

Answer 3

ADH action in kidney is mediated by binding to V2 receptors coupled to adenylate cyclase and cAMP
-cAMP activates PKA which prompts insertion of water channels into apical membrane of the cell

when removed, water channels withdraw from membrane and apical surface of cell becomes impermeable to water again

Question 4

what is one case where hypervolemia would cause decreased Na?

Answer 4

CHF would cause hypervolemia but decrease effective circulating volume despite increased volume
-decreased Na urine

Question 5

what happens in SIADH? if it’s associated with CHF

Answer 5

ADH levels are often normal, but have exaggerated activity

• ultimately develop a steady state
• decrease in apical water channel AQ-2 mRNA = vasopressin escape (downregulation in transcription)
• relatively common in mild in elderly, and often idiopathic
• bad prognostic sign if associated w/ CHF

Question 6

what stimulates and inhibits renin secretion by macula densa?

Answer 6

stimulate

• baroreceptors/myogenic reflexes in afferent arteriole
• SNS
• catecholamines
• Cl delivery of macula densa

inhibit

• ADH
• ANP
• maybe ANP and CNP

Question 7

how do NSAIDs affect renal function?

Answer 7

1. hemodynamic
2. acute interstitial nephritis w/ or w/o nephrotic synrome
   - acute kidney injury occurs with preexisting composure of renal perfusion-volume depletion, CHF, cirrhosis, diuretics, and advanced age
   - inhibit COX that make vasodilator prostaglandins PGE2 and PGI2. meaning that NSAIDs constrict afferent arterioles

Question 8

what should you NOT give if nephrotic syndrome edema?

Answer 8

don’t give diuretics

Question 9

what are the 5 diagnostic criteria of SIADH?

Answer 9

1. plasma osmolarity < 275 mOsm
2. inappropriately concentrated urine
3. euvolemia
4. urine Na > 40 mOsm
5. no diuretic use or renal/adrenal/thyroid disease

common cause of hyponatremia in hospitalized patients