Pathology

Question 1

What are the 4 types of RTA?

Answer 1

1- distal RTA
2- proximal RTA
3- mixed RTA
4- hyporeninemic hypoaldosteronism RTA

Question 2

What are the common causes of type 1 (distal) RTA?

Answer 2

-most commonly from autoimmune disorders (SLE, RA, Sjogren, thyroiditis, PBC
-inherited cause
-genetic associations (Marfan, Ehler-Danlos, sickle cell)
-nephrocalcinosis
-tubulointerstitial dx (chronic pyelonephritis, chronic interstitial nephritis, obstructive uropathy, renal txp rejection)
-hypergammaglobulinemia
-drugs (lithium, amphotericin B, NSAIDs, lead, antivirals)
-miscellaneous (idiopathic, familial hypercalciuria, glue sniffing)

Question 3

What are the common causes of type 2 (proximal) RTA?

Answer 3

-hypergammaglobulinemia
-inherited mutations
-drugs (heavy metals, carbonic anhydrase inhibitors (acetazolamide), aminoglycosides, valproate, tenofovir)
-autoimmune (SLE, Sjogren)
-miscellaneous (interstitial nephritis, Fanconi, vit D deficiency, 2nd hyperparathyroidism, chronic hepatitis

Question 4

What are the common causes of type 3 (mixed) RTA?

Answer 4

mutations in carbonic anhydrase II

Question 5

What are the common causes of type 4 (hyperkalemic) RTA?

Answer 5

-hyporeninemic hypoaldosteronism (diabetic nephropathy-destruction of JG apparatus d/t vascular hyalinosis)
-drugs (K-sparing diuretics, beta-blockers, NSAIDs, calcineurin inhibitors (cyclosporine, tacrolimus), ACEi’s, ARBs, renin inhibitors, heparin, bactrim)
-autoimmune (SLE)
-genetic (sickle cell, pseudohypoaldosteronism
-miscellaneous (interstitial nephritis, chronic obstruction of UT, adrenal insensitivity to angiotensin II, renal insufficiency

Question 6

What is the normal, adult GFR?

Answer 6

100 - 125mL/min

Question 7

In what part of the tubule does tubular reabsorption occur?

Answer 7

proximal tubule (67-88%)

Question 8

On what part of the nephron does acetazolamide work?

Answer 8

proximal convoluted tubule

Question 9

On what part of the nephron do osmotic diuretics (mannitol) work?

Answer 9

descending limb

Question 10

On what part of the nephron do loop diuretics work?

Answer 10

ascending limb

Question 11

On what part of the nephron do thiazide diuretics (HCTZ) work?

Answer 11

distal convoluted tubule

Question 12

On what part of the nephron do potassium-sparing (spironolactone) diuretics work?

Answer 12

distal part of distal convoluted tubule/proximal collecting duct (difficult to tell from picture)

Question 13

What part of the nephron does angiotensin II work on?

Answer 13

afferent arteriole

Question 14

What part of the nephron does ANP act on?

Answer 14

glomerulus

Question 15

What part of the nephron does ADH act on?

Answer 15

collecting duct

Question 16

What is the major active transport mechanism of the nephron?

Answer 16

reabsorption of sodium

Question 17

What are the 3 determinants of sodium reabsorption?

Answer 17

-GFR: if high the reabsorption is low
-aldosterone: augments Na reabsorption in distal tubule
-atrial natriuretic factor (ANF): lowers reabsorption

Question 18

How do you calculate creatinine clearance?

Answer 18

Ccreat = (Ucr x Uvolume)/(Scr x time)

Question 19

What is cystatin C

Answer 19

small protein produced by nucleated cells and eliminated by GFR
-similar to Scr but less dependent on muscle mass
-can detect AKI 1-2 days earlier than Scr
-not as good as Scr in cardiac surgery pts
-is much more expensive to test

Question 20

What is the MOA of furosemide?

Answer 20

inhibits the active Na/K/Cl co-transport pump on luminal cell membrane surface of the thick ascending limb of Henle loop