Renal USMLE Flashcards
ureters pass _______ uterine artery and ______ ductus deferens (retroperitoneal)
UNDER,UNDER
mneu: water (ureters) UNDER the bridge (artery, ductus deferens).
total body weight is ____% water
60
total body water is ___ intracellular fluid
2/3
total body water is 1/3 extracellular fluid what portion of this is plasma volume
1/4
ICF=
TBW-ECF
interstitial volume-
ECF-PV
60-40-20 rule (% of body weight)
60% total body water
40% ICF
20% ECF
plasma volume can be measured by this
radiolabeled albumin
extracellular volume can be measured by this
inulin
Cx=
UxV/P=volume of plama from which the substance is cleared completely per unit time
Cx=clearance of X
Ux=urine concentration of X
Px=Plasma concentration of X
V=urine flow rate
if Cx < GFR, then there is net tubular ________ of X
resorption
if Cx > GFR, then there is net tubular ________ of X
secretion
if Cx = GFR, then ___________
no net secretion or reabsorption
glomerular filtration barrier is responsible for filtration of plasma according to these 2 factors
size and net charge
what is the glomerular filtration barrier composed of
1) fenestrated capillary endothelium (size barrier)
2) Fuse basement membrane with heparan sulfate (negative charge barrier)
3) epithelial layer consisting of podocyte foot processes
what barrier of the glomerular filtration barrier is lost in nephrotic syndrome
charge barrier
what are some symptoms of nephrotic syndrome
albuminuria, hypoproteinemia, generalized edema, and hyperlipidemia
what is used to calculate GFR because it is freely filtered and is neither reabsorbed nor secreted
inulin
creatinine clearance is an approximate measure of what
GFR
GFR=
U(inulin)xV/P(inulin)=C(inulin)
effective renal plasma flow (ERPF can be estimated using _____ because it is both filtered and actively secreted in the proximal tubule. All _____ entering the kidney is excreted.
PAH
ERPF=
U(PAH)xV/P(PAH)=C(PAH)
RBF=
RPF/1-Hct
ERPF underestimates true RPF by how much?
~10%
filtration fraction (FF)=
GFR/RPF
what effect will afferent arteriole constriction have on
RPF:
GFR:
FF (GFR/RPF):
RPF:↓
GFR:↓
FF (GFR/RPF):NC
what effect will efferent arteriole constriction have on
RPF:
GFR:
FF (GFR/RPF):
what effect will afferent arteriole constriction have on
RPF:↓
GFR:↑
FF (GFR/RPF):↑
what effect will increased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF:NC
GFR:↓
FF (GFR/RPF):↓
what effect will decreased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR: ↑
FF (GFR/RPF):↑
what effect will constriction of ureter have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↓
FF (GFR/RPF):↓
free water clearance
C(H2O)=
V-C(osm)
V=urine flow rate
glucose at a normal level is completely reabsorbed where
proximal tubula
at plasma glucose of _____, glucosuria begins (threshold)
200mg/dL
at plasma glucose level of ______, transport mechanism is saturated (Tm)
350 mg/dL
amino acid resorption occurs by at least 3 distinct carrier systems, with competitive inhibition within each group. Secondary active transport occurs in the _________ and is saturable.
proximal tubule
what effect will decreased plasma protein concentration have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↑
FF (GFR/RPF):↓
what effect will constriction of ureter have on
RPF:
GFR:
FF (GFR/RPF):
RPF: NC
GFR:↓
FF (GFR/RPF):↓
free water clearance
C(H2O)=
V-C(osm)
V=urine flow rate
glucose at a normal level is completely reabsorbed where
proximal tubula
at plasma glucose of _____, glucosuria begins (threshold)
200mg/dL
this part of the nephron is called the “workhorse of the nephron”
early proximal convuluted tubule.
the early proximal convuluted tubule resorbes all of these 2 things and most of these 3 things
all of glucose and amino acids
most of the bicarb, sodium, and water
the early proximal convuluted tubule secretes this which will act as a buffer for secreted H+
ammonia
this part of the nephron passively reabsorbs water via medullary hypertonicity (impermeable to sodium)
thin descending loop of Henly
this part of the nephron actively reabsorbs Na+, K+, and Cl- and indirectly induces the reabsorption of Mg++ and Ca++. It is impermeable to H2O
Thick ascending loop of Henle
the early distal convuluted tubule actively reabsorbs these 2 ions. Here reabsorbion of Ca++ is under the control of PTH
Na+, Cl-
the collecting tubules resorb Na_ in exchange for secreting K+ or H+. This is regulated by this hormone
aldosterone
in the collecting tubules resorption of water is regulated by this hormone
ADH (vasopressin)
osmolarity of medulla can reach ______mOsm
1200
this is released by the kidneys upon sensing decreased BP
renin
renin cleaves angiotensinogen to this
ATN I (a decapeptide)
ATN I is cleaved by this enzyme, primarily in the lung capillaries and elsewehere, to ATN II (an osctapeptide)
Angiotensin-converting enzyme (ACE)
what are the actions of angiotensin II
1) potent vasoconstriction
2) release of aldosterone from the adrenal cortex
3) release of ADH from posterior pituitary
4) stimulates hypothalamus to increase thirst
what is the overal purpose of ATN II
increase intravascular volume and BP
this peptide released from atria may acti as a “check” on the renin-angiotensin system (e.g., in heart failure).
ANP
these are modified smooth muscle cells of afferent arteriole
JG cells
this is a Na+ sensor and part of the distal convoluted tubule
macula densa
JG cells secrete this in resoponse to low renal blood pressure, low Na+ delivery to distal tubule, and increased sympathetic tone
renin
what does the juxtaglomerular apparatus (JGA) consist of
JG cells and macula densa
when the JG cells secrete renin what does this lead to
increase in ATN II and aldosterone
JGA activates the renin-angiotensin system in defence of this
glomular filtration rate
juxta means
close by
Endocrine fxs of kidney: endothelial cells of peritubular capillaries secrete this in response to hypoxia
erythropoeietin
Endocrine fxs of kidney: conversion of 25-OH vit D to ________ by 1alpha-hydroxylase, which is activated by PTH
1,25-(OH)2 vit D
Endocrine fxs of kidney: JC cells secrete ____ in response to decrease renal arterial pressure and increase renal sympathetic discharge (B1 effect)
renin
Endocrine fxs of kidney: secretion of _________ that vasodilate the afferent arterioles to increase GFR
prostaglandins
this common class of drug can cause acute renal failure in high vasoconstrictive states by inhibiting the renal production of prostaglandins, which keep the afferent arterioles vasoldilated to maintain GFR
NSAIDs
Hormones acting on the kidney:
This hormone is secreted in response to increased atrial pressure and causes increase GFR and increase Na+ excretion
atrial natriuretic factor (ANF)
Hormones acting on the kidney: This hormone is secreted in response to decreased blood volume (via AT II) and increased plasma [K+]. It causes increased Na+ reabsorption, increase K+ secretion, increase H+ secretion
aldosterone
Hormones acting on the kidney:
This hormone is secreted in response to low blood volume.
renin
where is ATN I converted to ATN II by ACE
lung
Hormones acting on the kidney:
This hormone causes efferent arteriole constriction which leads to increase GFR and increase Na+ and HCO3- reabsorption
Angiotensin II
Hormones acting on the kidney:
This hormone is secreted in response to increase plasma osmolality and decreased blood volume. It binds to receptors on principal cells, causing increase number of water channels and increased H2O absorption
vasopressin/ADH
Hormones acting on the kidney:
This hormone is secreted in response to low plasma [Ca++]. It causes increase [Ca++] reabsorption (DCT), decrease PO4— reabsorrption (PCT, 1,25 (OH)3 vit D production ->increase Ca_ and PO4— resorptioon
PTH
Acid Base Physiology: Metabolic acidosis= pH: Pco2: [HCO3-]: compensatory response:
pH:↓
Pco2:↓
[HCO3-]:↓*
Compensatory response: hyperventilation
Acid Base Physiology: Metabolic alkalosis= pH: Pco2: [HCO3-]: compensatory response:
pH:↑
Pco2:↑
[HCO3-]:↑*
Compensatory response: hypoventilation
Acid Base Physiology: respiratory alkalosis= pH: Pco2: [HCO3-]: compensatory response:
pH:↑
Pco2:↓*
[HCO3-]:↓
Compensatory response: renal [HCO3-] reabsorption
Acid Base Physiology: respiratory acidosis= pH: Pco2: [HCO3-]: compensatory response:
pH:↓
Pco2:↑*
[HCO3-]:↓
Compensatory response: renal [HCO3-] secretion
what is the Henderson-Hasselbach equasion
pH=
pKa + log [HCO3-]/0.03 P(co2)
acid base compensations: metabolic acidosis
winter’s formula:
Pco2=1.5 (HCO3-) + 8 +/- 2
acid base compensations: metabolic alkalosis
pco2 ↑ O.7 per
1 HCO3-↑
acid base compensations: respiratory acidosis
acute-↑1HCO3- per 10CO2↑
chronic-↑3.5HCO3- per 10CO2↑
acid base compensations: respiratory alkalosis
acute-↓2HCO3- per 10CO2↓
chronic-↓5HCO3- per 10CO2↓
this syndrome is due to a bilateral renal agenesis which leads to oligohydramnios. This results in limb deformities, facial deformities, and pulmonary hypoplasia
Potter’s syndrome
mneu: babies w/ Potter’s can’t “Pee” inutero
what is the embryological malformation which leads to Potters syndrome
malformation of ureteric bud
this occurs when the inferior poles of both kidneys fuse.
horseshoe kidney
when a horshoe kidney ascends from the pelvis during fetal development the kidneys get trapped under this artery and remain low in the abdomen
inferior mesenteric
RBC casts in urine what is your differential
glomerular inflammation (nephritic syndromes), ischemia, or malignant hypertension
WBC casts in urine what is your differential
tubulointerstitial dz, acute pylonephritis, glomerular disorders
granular casts in urine what is it
acute tubular necrosis
waxy casts in urine what is it
advanced renal dz/CRF
presence of these indicates that hematuria/pyruia is of renal origin
casts
what type of blood cell do you see in the urine with bladder cancer
RBCs
what type of blood cell do you see in the urine with acute cystitis
WBCs
NephrItic syndrome is characterized by
I=inflammation
what signs and symptoms will you see in nephritic syndrome
hematuria, hypertension, oliguria, azoemia
give 6 examples of nephritic syndrome
1) acute poststreptococcal glomerulonephritis
2) rapidly progressive (crescentric) glomerulonepritis
3) Good pasture syndrome
4) membranoproliferative glomerulonepritis
5) IgA nephropathy (Berger’s dz)
6) Alport’s syndrome
this nephritic syndrome is most frequently seen in children. It may present with peripheral and periorbital edema. On light microscope the glomeruli may appear enlarged and hypercellular. There is a “lumpy bumpy apprearance. Neutrophils are presence. Elecron microscopy shows subepithelial humps. Immunoflurescent shows a granular pattern. It resolves spontaneously.
Acute postreptococcal glomerulonephritis
this nephritic syndrome has many causes it is characterized by a rapid course to renal failure. LM & IF shows crescent moon shape
rapidly progressive (crescentic glomerulonephritis
this nephritic syndrome often presents with hemoptysis or hematuria. IF shows a linear pattern and anti-GBM antibodies
Goodpasture’s syndrome
what type of hypersensitivity is goodpasture’s syndrome
type II
this nephritic syndrome slowly progresesses to renal failure. EM shows subendothelial humps, “tram track.”
membranoproliferative glomerulonephritis
this nephritic syndrome is often postinfectious. It is mild and IF and EM show mesangial deposits of IgA
IgA nephropathy (Berger’s dz)
this nephritic syndrome is a collagin IV mutation. There is a split basement membrane. It is often manifested by nerve deafness and ocular disorders.
Alport’s syndrome
NephrOtic syndrome is characterized by this
O=protinurea
what are the signs and symptoms of nephrotic syndrome
massive protinuria, hypoalbuminemia, peripheral and periorbital edema, hyperlipidemia
give 5 causes of nephrotic syndrome
1) membranous glomerulonephritis
2) minimal change dz (lipoid nephrosis)
3) focal segmental glomerular sclerosis
4) diabetic nephropathy
5) SLE
this is a common cause of nephrotic syndrome in adults. LM: diffuse capillary and basement membrane thickening. IF: granular pattern. EM: “spike and dome”
membranous glomerulonephritis
this is a common cause of nephrotic syndrome in children. LM: normal glomeruli. EM foot process effacement.
It responds well to steroids
minimal change dz (lipoid nephrosis)
this type of nephrotic syndrome shows segmental sclerosis and hyalinosis under LM. It causes a more severe dz in HIV pts
Focal segmental glomerular sclerosis
this nephrotic syndrome shows Kimmelsteil Wilson “wire loop” lesions and basement membrane thickening in light microscope
diabetic nephropathy
this cause of nephrotic syndrome has 5 patterns of renal involvement. LM: in membranous glomerulonephritis pattern, wire-looped lesion with subendothelial deposits
SLE
kidney stones can lead to severe complications such as
hydronephrosis and pyelonephritis
this is the most common kidney stone (75-85%). They tend to recur.
calcium (calcium oxalate or calcium phosphate)
Ca++ kidney stones are radio____
opaque
what are some syndromes that can cause calcium kidney stones
Cancer, increase PTH, increase vit D, milk alkali syndrome.
this is the 2nd most common kidney stone. It is caused by infection with urease-positive bugs (Proteus vulgaris, staphylococcus, Klebsiella). They can form Staghorn calculi that can be a nidus for UTIs
Ammonium magnesium Phosphate (struvite)
Ammonium magnesium Phosphate (struvite) stones are radio_____
opaque
this type of kidney stone has a strong associateion with hyperuricemia (e.g., gout). Often seen in dzz with increase cell turnovers, such as leukemia and myeloproliferative disorders
uric acid
uric acid stones are radio____
lucent
this type of kidney stone is most often secondary to cystinuria
cystine
cystine stones are most often secondary to cystinuria and are radio______
faintly radiopaque
this is the most common renal malignancy. It is most common in men ages 50-70. There is increased incidence with smoking and obesity. It manifests clinically with hematuria, palpable mass, secondary polycythemia, flank pain, fever, and weight loss.
renal cell carcinoma
renal cell carcinoma is associated with this dz and gene deletion
von Hippel-Lindau and gene deletion in chromosome 3
renal cell carcinoma originates in renal tubule cells and spreads to the polygonal clear cells. It invades the IVC and spreads thorugh this route
hematogenously.
renal cell carcinoma is commonly associated with paraneoplastic syndromes. give some examples.
ectopic EPO, ACTH, PTHrP, and prolactin
this is the most common renal malignancy of early childhood (ages 2-4). Presents with huge palpable flank mass, hemihypertrophy.
Wilms tumor
Wilms tumor is associated with deletion of this tumor suppressior gene on this chromosome
WT1 on chromosome 11
Wilms tumor can be part of WAGR complex. What is this
wilms’ tumor
Aniridia
GU malformation,
mental motor retardation
this is the most common tumor of urinary tract system (can occur in renal calyces, renal pelvis, ureters, and bladder).
transitional cell caricinoma
this is suggestive of bladder cancer
painless hematuria.
transitional cell caricinoma is associated with problems in your Pee SACS (mneu). What does this mean
Phenacetin Smoking Aniline dyes Cyclophosphamide Schistosomiasis
pt presents w/ fever and CVA tenderness. What do you suspect?
acute pyelonephritis
what part of the kidney does acute pyelonephritis effect
affects cortex w/ relative sparing of glomeruli/vessels.
what is pathognomonic for acute pyelonephritis
white cell casts in urine
this conditon is characterized by coarse, asymmetric corticomedullary scarring.
chronic pyelonephritis
chronic pyelonephritis looks like this tissue histologically
thyroid (thyroidization of kidney)
In chronic pyelonephritis, tubules contain ______ casts
eosinophilic
this is caused by an acute generalized infarction of the cortices of both kidneys. It is likely due to a combination of vasospasm and DIC. It is associated with obstetric castrophes (e.g., abruptio placentae) and septic shock
Diffuse cortical necrosis
this is the most common cause of acute renal failure. It is reversible, but fatal if left untreated. It is associated with renal ischemia (e.g., shock), crush injury (myoglobinuria), toxins. Death most often occurs during the initial oliguric phase. Recovery is in 2-3 weeks.
acute tubular necrosis
renal papillary necrosis is associated with four conditions
1) diabetes mellitus
2) acute pyelonephritis
3) chronic phenacetin use
4) sickle cell anemia
this is associated with an abrupt decline in renal fx with increased creatinine and BUN over a period of several days
acute renal failure
this type of acute renal failure is characterized by decreased RBF (e.g., hypotension) ->decreased GFR. Na+/H2O are retained by the kidney.
Labs:
Urine osmo: >500
Urine Na+: 20
prerenal failure
this type of acute renal failure is generally due to acute tubular necrosis or ischemia/toxins. Patchy necrosis leads to debris obstructing tubule and fluid backflow across necrotic tubule -> decreased GFR. Urine has epithelial/granular casts.
Labs:
Urine osmo: 20
Fe(Na): >2%
BUN/Cr ratio:
intrinsic renal failure
this type of acute renal failure is due to outflow obstruction (stones, BPH, neoplasia). Develops only with bilateral obstruction Labs: Urine osmo: 40 Fe(Na): >4% BUN/Cr ratio: >15
Postrenal failure
acute renal failure is often due to this
hypoxia
chronic renal failure is often due to these two chronic dz
htn
dbts
renal failure results in a failure to make urine and a failure to excrete this type of waste
nitrogenous
this is a clinical sydrome marked by increase BUN and creatinine and associated symptoms
uremia
renal failure can result in anemia. why?
failure of erythropoitetin production
renal failure can result in renal osteodystrophy. why?
failure of active vit D production
renal failure can result in cardiac arrhythmias. why?
hyperkalemia
renal failure can result in metabolic acidosis. why?
decreased acid secretion and decrease generation of HCO3-
renal failure can result in CHF and pulmonary edema. why?
Na+ and H2O excess
what are some other things renal failure can result in?
uremic encephalopathy
chronic pyelonephritis
hypertension
low serum Na+ results in
disorientation, stupor, coma
high serum Na+ results in
neurologic: irritability, delirium, coma
low serum Cl- is often secondary to this
metabolic alkalosis
high serum Cl- is often secondary to this
non-anion gap acidosis
low serum K+ results in
U waves on ECG, flattened T waves, arrhythmias, paralysis
high serum K+ results in
peaked T waves, arrhytmias
low serum Ca++ results in
tetany, neuromuscular irritability
high serum Ca++ results in
delirium, renal stones, abdominal pain
low serum Mg++ results in
neromuscular irritability, arrhythmias
high serum Mg++ results in
delirium, decreased DTRs, cardiopulmonary arrest
low serum PO4– results in
low-mineral ion product causes bone loss
high serum PO4– results in
low-mineral ion product causes metastatic calcification, renal stones
