Renal Flashcards
most common site of obstruction in fetus
ureteropelvic junction
multicystic dysplastic kidney
due to abnormal interaction between ureteric bud and metanephric mesenchyme
- non functional kidney of cysts and connective tissue
glomerular filtration barrier
- fenestrated capillaries provide size barrier
- BM provides charge membrane (lost in nephrotic syndrome)
- epithelial layer has podocytes
equations for GFR, RPF and FF
GFR = Cinulin = Ui x V/Pi RPF = RBF x (1-Hct) FF = GFR / RPF = GFR / (RBFx(1-Hct))
Hartnup disease
deficiency in neutral AA transporter, leading to dec tryptophan uptake
- can lead to pellagra-like symptoms because niacin is derived from tryptophan
- treat with high protein diet and nicotinic acid
early proximal convoluted tubule functions
- reabsorb AA, glucose, and most H2O, Na, Cl, Phos, K
- secretes NH3 (buffers H+)
- PTH inhibits Na/phos transport, inc phos excretion
- ATII increases Na/H exchange, inc Na, H2O and HCO2- absorption (permitting contraction alkalosis)
- 65-80% of Na reabsorbed
thin descending loop of henle
- water passively reabsorbed due to concentration gradient
thick ascending loop of henle
- actively reabsorbs Na, K and Cl through Na/K/2Cl transporter
- Mg and Ca reabsorbed paracellularly 2/2 K backleak
- impermeable to H2O
- 10-20% of Na reabsorbed
early distal convoluted tubule
- actively reabsorbs Na, Cl
- PTH inc Ca/Na exchange, inc Ca reabsorption
- 5-10% of Na reabsorbed
collecting tubule
reabsorbs Na in exchange for K+ and H+ (mediated by aldosterone)
- ADH acts on V2 receptor and inc insertion of aquaporins
- 3-5% of Na reabsorbed
Fanconi syndrome
- reabsorptive defect in the PCT
- inc excretion of AA, glucose, HCO3- and phos
- may result in metabolic acidosis
- causes include hereditary defects (Wilson disease), ischemia and nephrotoxins/drugs
Bartter syndrome
- reabsorptive defect in the thick ascending loop of Henle
- AR, affects Ka/K/2Cl transporter
- hypokalemia and metabolic alkalosis, hypercalciuria
Gitelman syndrome
- reabsorptive defect of NaCl in DCT
- AR
- hypokalemia and metabolic alkalosis
- NO hypercalciuria
Liddle syndrome
- inc Na reabsorption in distal and collecting tubules
- AD
- results in hypertension, hypo K, metabolic alkalosis, low aldo
- treat with amiloride
effects of Angiotensin II
- acts on AT I receptors on vascular smooth muscle to constrict
- constricts efferent arteriole to inc FF despite low volume state (compensatory Na reabsorption)
- stimulates aldo (inc Na reabsorption)
- stimulates ADH (inc H2O reabsorption)
- stimulates prox tubule Na/H activity
- stimulates hypothalamus (thirst)
juxtaglomerular apparatus function and B-blockers effect on it
- JG cells (modified smooth muscle cells) sense dec renal blood flow and release renin
- macula densa senses NaCl in the distal convoluted tubule –> renin
- B1 sympathetic tone also increases renin release
- b blockers block the B1 receptors on JGA, causing decreased renin release
Vit D in the kidney
proximal tubule cells convert 25-OH vit D to 1,-25 OH2 vit D via 1-alpha hydroxylase
- this enzyme is stimulated by PTH
NSAIDs
- block the protective vasodilation of the afferent arteriole that usually would increase RBF
- can constrict the afferent arteriole and dec RBF so much they cause acute renal failure
Winter’s formula
PCO2 = 1.5[HCO3-] + 8 +/- 2
causes of anion gap metabolic acidosis
MUDPILES
-methanol, uremia, DKA, propylene glycol, iron tablets or INH, lactic acidosis, ethylene glycol, salicylates
causes of non-anion gap metabolic acidosis
HARD ASS
- hyperalimentation, addisons, RTA, diarrhea, acetazolamide, spironolactone, saline infusion
metabolic alkalosis with low urine Cl
- vomiting, NG aspiration, prior diuretic use
metabolic alkalosis with high urine Cl and hypo/euvolemia
- diuretic use, Barter and Gittelman syndromes
metabolic alkalosis with high urine Cl and hypervolemia
excess mineralocorticoids (primary hyperaldo, cushing disease, ectopic ACTH prodcuction)
renal tubular acidosis
d/o of the renal tubules which leads to a non-anion gap hyperchloremic metabolic acidosis
RTA 1
- pH > 5.5
- defect in alpha intercalated cell’s ability to secrete H+ (no new HCO3- is generated)
- associated with hypokalemia and inc risk for calcium phosphate stones
- causes: amphotericin B, analgesic nephropathy, MM, congenital urinary anomalies
RTA 2
- pH < 5.5
- defect in prox tubule HCO3- reabsorption
- associated with hypoK, inc risk for hypophosphatemic rickets
- causes: Fanconi syndrome, chemicals toxic to prox tubules (lead, aminoglycosides), and carbonic anhydrase inhibitors
RTA 4
- pH < 5.5
- hypoaldo, aldo resistance or K sparing diuretics
- hyperkalemia impairs ammoniagenesis, dec H+ excretion into the urine
RBC casts mean
glomerulonephritis, ischemia or malignant hypertension
WBC casts mean
tubulointerstitial inflammation, acute pyelo, transplant rejection
fatty casts (“oval fat bodies”) mean
nephrotic syndrome
granular (“muddy brown”) casts mean
acute tubular necrosis
waxy casts mean
advanced renal disease/chronic renal failure
hyaline casts mean
nonspecific, can be norm esp in concentrated urine
eosinophilic casts mean
MM, chronic pyelo
nephritic syndromes
inflammatory process leading to hematuria and RBC casts in the urine
- assoc with azotemia, oliguria, HTN and proteinuria (< 3.5mg/day)
- acute poststrep glomerulonephritis, RPGN, IgA nephropathy, Alport syndrome
nephtitic/nephrotic syndromes
-diffuse proliferative glomerulonephritis, membranoproliferative glomerulonephritis
nephrotic syndromes
- > 3.5 mg protein/day, hyperlipidemia, fatty casts, edema, hypercoaguability
- FSGS, Membranous nephropathy, MCD, amyloidosis, diabetic glomerulonephropathy
FSGS
LM - segmental sclerosis and hyalinosis
IF -ve
EM - effacement of foot process
- most common cause of nephrotic syndrome in hispanics and AA
- idiopathic or 2/2 HIV, sickle cell, heroin, obesity, interferon treatment, CKD
- inconsistent response to steroids
membranous nephropathy microscope findings
LM - diffuse capillary and GBM thickening
IF - granular as a result of immune complex deposition. nephrotic presentation of SLE
EM - “spike and dome” appearance with subendothelial deposits
membranous nephropathy epi/cause
- most common cause of nephrotic syndrome in caucasian adults
- can be due to Ab to phospholipase A2 receptor, drugs (NSAIDS), HBV/HCV, SLE or solid tumors
- poor response to steroids
MCD
LM normal, neg IF, EM - effacement of foot processes
- most common in kids
- triggered by recent infection, immunization, Hodgkins Lymphoma
- excellent response to steroids
amyloidosis
- LM - congo red stain shows apple-green birefringence under polarized light
- associate with chronic conditions (TB, MM, rheumatoid arthritis)
Type I MPGN
- subendothelial immune complex deposits with granular IF, “tram-track” appearance due to GBM splitting
- nephritic/nephrotic syndrome
- assoc with HBV, HCV
Type II MPGN
- inramembranous IC deposits, “dense deposits”
- assoc with C3 nephritic factor (stabilizes C3 convertase –> serum C3 levels)
diabetic glomerulonephropathy
LM - mesangial expansion, GBM thickening, eosinophilic nodular glomerulosclerosis
- glycosylation of GBM – inc permeability and thickening
- glycosylation of efferent arterioles inc GFR, leads to mesangial expansion
acute poststreptococcal glomerulonephritis
- LM - glomeruli enlarged and hypercellular
- IF - “starry sky” granular appearance and “lumpy bumpy” due to IgG, IgM and C3 deposition along GBM and mesangium
- EM - immune complex humps
- 2 weeks after GAS pharyngitis or skin infection
- Type III HS reaction that resolves spontaneously
- coca-cola urine, ASO titer and low C3
rapidly progressive (crescentic) glomerulonephritis
- LM and IF - crescent moon shape (crescents consist of fibrin and plasma proteins with glomerular parietal cells, monocytes and macrophages)
- 2/2 Goodpasture’s disease, Wegener’s, Microscopic polyangiitis
- poor prognosis
diffuse proliferative glomerulonephritis
- due to SLE or MPGN
- LM - “wire looping” of capillaries
- EM - subendothelial and sometimes intramembranous IgG-based ICs often with C3 deposition
- IF - granular
- most common cause of death from SLE
IgA nephropathy (Berger disease)
- LM - mesangial proliferation
- EM - mesangial IC deposits
- IF - IgA based IC deposits in the mesangium
Seen with HSP. - often presents with a URI or acute gastroenteritis (“a few days after a flu-like illness”)
alport syndrome
- mutation of type IV collagen – thinning and splitting of the glomerular basement membrane. most commonly x linked
calcium oxalate kidney stones
- radioopque and envelope/dumbbell shaped
- promoted by hypercalciuria
- can result from ethylene glycol, vit C abuse, crohns
- treat with thiazides and citrate (prevents precipitation)
ammonium magnesium phosphate kidney stones
- radioopaque and coffin lid shaped
- caused by infection by urease + bugs, because they alkalinize the urine
- treat infection, remove stones
uric acid stones
- radiolucent, rhomboid or rosettes
- risk factors include decreased urine volume, arid climates and acidic pH
- can be 2/2 gout or high cell turnover states (leukemia)
- treat by alkalinizing urine
cystine stones
radioopaque and hexagonal
- sodium nitroprusside test +
- treat by alkalinizing the urine and hydrating
renal cell carcinoma
- originates from the proximal tubule cells –> polygonal clear cells filled with accumulated lipids and carbs
- hematuria, palpable mass, polycythemia, flank pain, fever, weight loss
- invades renal vein/IVC and spreads hematogenously
- golden yellow on macroscopic exam
- resection and immunotherapy, resistant to chemo
renal oncocytoma
- benign epithelial cell tumor, well circumscibed with central scar
- large eosinphilic cells with abundant mitochondria without perinuclear clearing
- painless hematuria, flank pain, abdominal mass
Wilms tumor
- most common renal malignancy in kids (2-4)
- large palpable flank mass and/or hematuria
- “loss of function” mutations to tumor suppressor genes WT1 or WT2
- assoc with VHL or WAGR complex (Wilms tumor, Aniridia, GU malformations, Retardation)
Transitional Cell Carcinoma
- painless hematuria with no casts
- associated with problems with your Pee SAC: phenacetin, smoking, aniline dyes, and Cyclophosphamide
squamous cell carcinoma of the bladder
- due to chronic iritation of the bladder –> squamous metaplasia and dysplasia
- schistosomiasis, chronic cystitis, smoking, chronic nephrolithiasis
- presents with painless hematuria
acute infectious cystitis
- causes: E. coli, s. saprophyticus (sexually active women), Klebs, Proteus, adenovirus (hemorrhagic cystitis)
- sterile pyuria and neg urine cultures seen with gonorrhea and chlamydia
acute pyelo
- WBC casts in the urine
- complications include chronic pyelo, renal papillary necrosis, and perinephric abscess
chronic pyelo
coarse asymmetric corticomedullary scarring, blunted calyx
- tubules contain eosinophilic casts resembling thyroid tissue (thyroidization of the kidney)
ATN phases
- inciting event
- maintenance phase - oliguric, lasts 1-3 weeks with risk of hyperkalemia, met acidosis, volume overload, inc creat and BUN
- recovery phase - polyuric, BUN and Cr fall, risk of hypoK, hypoMg, hypoPhos, hypoCa
- can be ischemic (prox tubule/thick ascending limnb) or nephrotoxic (prox tubule)
renal papillary necrosis
- sloughing of renal papillae - gross hematuria and proteinuria
- assoc with DM, acute pyelo, chronic phenacetin use, sickle cell
prerenal/renal/postrenal
urine osmolarity - > 500, >40, >40
FeNa - 2%, >1-2%
BUN/Cr - >20, 15
consequences of renal failure
MAD HUNGER
- Metabolic Acidosis, Dyslipidemia, Hyperkalemia, Uremia, Na/H2O retention, Growth retard/DD in kids, EPO failure, Renal osteodystrophy
- can’t excrete phos or reabsorp Ca –> low Phos, High Ca, inc PTH, subperiosteal thinning of bones
