Renal, Endo, Repro Flashcards
Pronephros, Mesonephros, Metanephros, Ureteropelvic junction
Pronephros-week 4; then degenerates
Mesonephros- interim kidney 1st trimester; contributes to male genital tract
Metanephros-permanent; 1st appears in 5th week of gestation
- Ureteric bud- derived from caudal end of mesonephros; gives rise to ureter, pelvises, calyces, and collecting ducts; fully canalized by 10th week
- Metanephric mesenchyme- ureteric bud interacts /w this tissue; induces differentiation & formation of glomerulus to distal convoluted tubule
Ureteropelvic junction – last to canalize-> most common site of obstruction (hydronephrosis) in fetus
Potter sequence (syndrome)
Potters sequence (syndrome) Oligohydramnios (too little surrounding amniotic fluid- important expansion fluid) > compression to fetus > limb deformities, facial deformities, compression of chest and; lack of fluid aspiration > pulmonary hypoplasia > death.
Causes:Autosomal Recessive PKD, posterior urethral valves, bilateral renal agenesis
- low-set ears and retrognathia
POTTER syndrome associated with: Pulmonary hypoplasia Oligohydramnios (trigger) Twisted face Twisted skin Extremity defects Renal failure (in utero)
Horshoe Kidney
Horseshoe Kidney -Inferior poles of both kidneys fuse. Get trapped under inferior mesenteric artery and remain low in the abdomen.
- note: the ureter has to go up and over the horseshoe: so place for obstruction
- Kidney functions normally. Increased risk for ureteropelvic junction obstruction, hydronephrosis, renal stones, and rarely renal cancer (Wilms tumor).
- Associated with **Turner syndrome; or Trisomy 13, 18, and 21 - real problems are internal - renal and cardiovascular diseases
Multicystic dysplastic kidney
Duplex collecting system
Congenital solitary functioning kidney
Multicystic dysplastic kidney
Ureteric bud fails to induce differentiation of metanephric mesenchyme (connections aren’t formed), nonfunctional kidney consisting of cysts and connective tissue. Often diagnosed prenatally via ultrasound.
{Duplex collecting system}
Bifurcation of ureteric bud before it enters the metanephric blastema creates a Y-shaped bifid ureter. Duplex collecting system can alternatively occur through two ureteric buds reaching and interacting with metanephric blastema. Strongly associated with vesicoureteral reflux and/or ureteral obstruction, risk for UTIs.
Congenital solitary functioning kidney Condition of being born with only one functioning kidney. Majority asymptomatic with compensatory hypertrophy of contralateral kidney, but anomalies in contralateral kidney are common.
-one dysplastic kidney isn’t getting what it needs and generates RAS > leading to hypertension, and underactivation of the good kidney.
Fusion of the caudal portions of the kidneys during embryonic development is most likely to result in which of the following congenital conditions?
A. Bicornuate uterus B. Cryptorchidism C. Horseshoe kidney D. Hypospadias E. Renal agenesis
.C
During the development the kidneys typically ascend from a position in the pelvis to a position high on the posterior abdominal wall. Although the kidneys are bilateral structures, occasionally the inferior poles of the two kidneys fuse. When this happens, the ascent of the fused kidneys is arrested by the first midline structure they encounter, the inferior mesenteric artery. The incidence of horseshoe kidney is about .25% of the population
You worry about stones
Which of the following congenital malformations will most predictably result in oligohydramnios?
A. Anencephaly B. Pyloric stenosis C. Renal agenesis D. Tracheoesophageal fistula E. Maternal diabetes
C. renal agenesis - others are examples of polyhydraminos
in normal kidney development the kidneys function during the fgetal period with the resulting urine contributing to the fluid in the amniotic cavity. When kidneys fail to develop, this contribution to the fluid is missing and decreased amniotic fluid (oligohydramnios results)
Failure to urinate during embryonic or fetal life usually causes respiratory difficulties postnatally. Which of the following relationships best describes this situation?
A. Oligohydramnios linked with hypoplastic lungs B. Polycystic kidneys linked to tracheoesophageal fistula C. Polyhydramnios linked with hyperplastic lungs D. Renal agenesis linked to insufficient surfactant E. Urethral obstruction linked to ectopic viscera
.A
There is some evidence that oligohydramnios is linked to hypoplastic lungs, this is apparently not a genetic link but rather related to importance of adequate amniotic fluid in normal lung development.
Renal blood flow
Left kidney taken for transplant from living donors because it has a longer renal vein.
Renal blood flow: renal artery > segmental artery> interlobar artery > arcuate artery > interlobular arteryà afferent arteriole > glomerulus > efferent arteriole > vasa recta/ peritubular capillaries > venous outflow
One of three major portal circulations in the body: two connected capillary beds. Glomerulus and peritubular capillaries
Glomerular filtration barrier
Responsible for filtration of plasma according to size and net charge.
Composed of fenestrated capillary endothelium (size barrier), fused basement membrane with heparin sulfate (negative charge barrier), epithelial layer consisting of podocyte foot processes
The charge barrier is lost in nephrotic syndrome, resulting in albuminuria (negative), hypoproteinemia, generalized edema (face, arm, leg, abdomen is edemic, not enough albumin in the blood so it goes out), and hyperlipidemia. Normal barrier is negatively charged, if albumin wants to get in, it wants to go.
Nephrin also maintains slit integrity (holds the podocytes together). Genetic mutations in nephrin cause massive proteinuria
Ureters anatomical location relative to vessels or ducts
Ureters pass under uterine artery (female) and under the vas deferens (male). “Water under the bridge”
Ligation of uterine or ovarian vessels may damage ureter leading to obstruction or leak.
Ovarian arteries are also anterior to the ureter
Ligation of ovarian vessels may damage ureter.
A 57-year-old man is admitted to the emergency department with left flank pain. Blood tests indicate hematuria and anemia. A magnetic resonance scan reveals that blood flow in the left renal vein is being occluded by an arterial aneurysm where the vein crosses the aorta. The aneurysm is most likely located in which of the following arteries?
A. Celiac B. Inferior mesenteric C. Left colic D. Middle colic E. Superior mesenteric
Nutcracker syndrome
-the superior mesenteric artery lies super superior and anterior to the left renal vein as the vein passes to its termination in the inferior vena cava. An aneurysm of the superior mesenteric artery would therefore be most likely to occlude the left renal vein. Do no confuse with SMA or Wilkie’s syndrome which is entrapment of the third portion of the duodenum.
Inferior =horseshoe
GFR
Use the following clinical laboratory test results, what is the GFR?
Urine flow rate = 1 ml/min Urine inulin concentration = 100 mg/ml Plasma inulin concentration = 1 mg/ml
A) 25ml/min B) 50 ml/min C) 100 ml/min D) 125ml/min E) None of the above
Glomerular filtration rate (GFR):
• Inulin clearance can be used to calculate GFR because it is freely filtered
and is neither reabsorbed nor secreted.
• Normal GFR=100mL/min.
• Creatinine clearance is an approximate measure of GFR. It slightly
overestimates GFR because creatinine is moderately secreted by the renal
tubules.
Clearance = urine flow rate x urine inulin concentration/ plasma inulin concentration
concentrations = mg/ml so they cancel out and you are only left with ml/min
100 x 1/1 = 100
Autoregulation of GFR
Autoregulation of GFR is due to two specific effects:
1) Myogenic-
Increased BP in the AA causes vasoconstriction in the AA reducing GFR. Probably more important in protecting kidney from HTN damage
2) Tubuloglomerular feedback (shown here)- Increased BP increases GFR which leads to increased salt delivery to the macula densa and secondarily AA constriction. This then reduces GFR. Increased salt delivery to the macula densa also reduces renin release from the JG cells. This eventually results in decreased generation of angiotensin II. Ang II preferentially constricts the EA. So in its absence, the EA is dilated and GFR is reduced. Opposite effects occur when GFR is reduced.
Glucose clearance and amino acid clearance
Glucose clearance Glucose at normal plasma level is completely reabsorbed in proximal tubule by a Na+/glucose cotransport mechanism. At plasma glucose of ~200 mg/dL, glucosuria begins (above threshold)
Amino acid clearance
Sodium-dependent transport in proximal tubule reabsorb amino acids.
Tu b u l o g l o m e r u l a r feedback explains how high protein diets increase GFR. This also explains why GFR is increased in early diabetes mellitus. Both conditions use PCT sodium to reabsorb either amino acids or glucose, reducing distant delivery of NaCl to the macula densa.
Filtration factor
Filtration Factor (FF)=GFR/RPF (normal 20%) GFR can be estimated with creatinine clearance RPF can be estimated with PAH clearance