Pathology Flashcards
What are the 4 types of RTA?
1- distal RTA
2- proximal RTA
3- mixed RTA
4- hyporeninemic hypoaldosteronism RTA
What are the common causes of type 1 (distal) RTA?
-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)
What are the common causes of type 2 (proximal) RTA?
-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
What are the common causes of type 3 (mixed) RTA?
mutations in carbonic anhydrase II
What are the common causes of type 4 (hyperkalemic) RTA?
-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
What is the normal, adult GFR?
100 - 125mL/min
In what part of the tubule does tubular reabsorption occur?
proximal tubule (67-88%)
On what part of the nephron does acetazolamide work?
proximal convoluted tubule
On what part of the nephron do osmotic diuretics (mannitol) work?
descending limb
On what part of the nephron do loop diuretics work?
ascending limb
On what part of the nephron do thiazide diuretics (HCTZ) work?
distal convoluted tubule
On what part of the nephron do potassium-sparing (spironolactone) diuretics work?
distal part of distal convoluted tubule/proximal collecting duct (difficult to tell from picture)
What part of the nephron does angiotensin II work on?
afferent arteriole
What part of the nephron does ANP act on?
glomerulus
What part of the nephron does ADH act on?
collecting duct
What is the major active transport mechanism of the nephron?
reabsorption of sodium
What are the 3 determinants of sodium reabsorption?
-GFR: if high the reabsorption is low
-aldosterone: augments Na reabsorption in distal tubule
-atrial natriuretic factor (ANF): lowers reabsorption
How do you calculate creatinine clearance?
Ccreat = (Ucr x Uvolume)/(Scr x time)
What is cystatin C
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
What is the MOA of furosemide?
inhibits the active Na/K/Cl co-transport pump on luminal cell membrane surface of the thick ascending limb of Henle loop
