Renal, Endo, Repro

Question 1

Pronephros, Mesonephros, Metanephros, Ureteropelvic junction

Answer 1

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

Question 2

Potter sequence (syndrome)

Answer 2

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)

Question 3

Horshoe Kidney

Answer 3

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

Question 4

Multicystic dysplastic kidney

Duplex collecting system

Congenital solitary functioning kidney

Answer 4

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.

Question 5

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

Answer 5

.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

Question 6

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

Answer 6

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)

Question 7

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

Answer 7

.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.

Question 8

Renal blood flow

Answer 8

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

Question 9

Glomerular filtration barrier

Answer 9

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

Question 10

Ureters anatomical location relative to vessels or ducts

Answer 10

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.

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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

Question 13

Autoregulation of GFR

Answer 13

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.

Question 14

Glucose clearance and amino acid clearance

Answer 14

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.

Question 15

Filtration factor

Answer 15

Filtration Factor (FF)=GFR/RPF (normal 20%) GFR can be estimated with creatinine clearance RPF can be estimated with PAH clearance

Question 16

A 55-year-old male patient with hypertension has had his blood pressure reasonably well controlled by administration of a thiazide diuretic. During his last visit (6 months ago) his blood pressure was 130/75 mm Hg and his serum creatinine was 1 mg/dL (nl, 0.6-1.2). He has been exercising regularly for the past 2 years, but recently has complained of knee pain and began taking large amounts of a nonsteroidal anti- inflammatory drug. When he arrives at your office, his blood pressure is 155/85 and his serum creatinine is now 2.5 mg/dL. Which of the following best explains his increased serum creatinine?
A) Increased efferent arteriolar resistance that reduced GFR B) Increased afferent arteriolar resistance that reduced GFR C) Increased glomerular capillary filtration coefficient that reduced GFR D) Increased angiotensin II formation that decreased GFR E) Increased muscle mass due to the exercise

Answer 16

.
B
NSAIDs inhibit synthesis of prostaglandins which in turn causes constriction of afferent arterioles that can reduce GFR. The decrease in GFR in turn leads to an increase in serum creatinine. Increased efferent arteriole resistance and increased glomerular capillary filtration coefficient would both tend to increase rather than reduce GFR. Increasing muscle mass due to exercise would cause little change in serum creatinine.

Question 17

A 36 year old patient with chronic renal disease is followed in your practice. His serum creatinine increases from 1.0 to 2.0 mg/dL. Which of the following is most likely true about his renal function? 1.  You should be following renal function using a serum inulin
concentration, not a serum creatinine 2.  There has been a large decrease in his renal function 3.  There has been a small decrease in his renal function 4.  There has been no change in his renal function

A 36 year old patient with chronic renal disease is followed in your practice. His serum creatinine increases from 4.0 to 8.0 mg/dL. Which of the following is most likely true about his renal function?
1.  You should be following renal function using a serum inulin
concentration, not a serum creatinine 2.  There has been a large decrease in his renal function
3.  There has been a small decrease in his renal function
4.  There has been no change in his renal function

Answer 17

filtered load (constant) = GFR x plasma concentration

so if renal function is halved, creatinine is doubled.

They BOTH see there has been a large decrease in renal function (50%)

Its a ratio.

Question 18

The maximum clearance rate possible for a substance that is totally cleared
from the plasma is equal to which of the following?
A) GFR
B) Filtered load of that substance
C) Urinary excretion rate of that substance
D) Renal plasma flow
E) Filtration fraction

Answer 18

D.

if a substance is completely cleared form the plasma, the clearance rate of that substance would equal total renal plasma flow. In other words, the total amount of substance delivered to the kidneys in the blood (renal plasma flow x concentration of substance in blood would equal the amount of that substance excreted in the urine. Complete renal clearance of a substance would require both.

• GFR is partial clearance of plasma (1/5) if GFR is 100 then RPF is 500.
• filtered load isn’t maximally cleared
• if GFR
• Renal plasma flow is afferent volume

Question 19

Which of following statement is correct when using serum PAH to estimate RBF.
A) A concentration of PAH below the Tm should be used so that PAH is both filtered at the glomerulus and completely secreted in the PCT
B) A concentration of PAH below the Tm should be used so that PAH is only filtered at the glomerulus.
C) A concentration of PAH above the Tm should be used so that PAH is both filtered at the glomerulus and completely secreted in the PCT
D) A concentration of PAH above the Tm should be used so that PAH is only filtered at the glomerulus.

Answer 19

A

Question 20

One gram of mannitol was injected into a woman. After equilibration, a plasma sample had a mannitol concentration of 0.08 g/ L. During the equilibration period, 20% of the injected mannitol was excreted in the urine. The subject’s
(A) extracellular fluid (ECF) volume is 1 L (B) intracellular fluid (ICF) volume is 1 L (C) ECF volume is 10 L (D) ICF volume is 10 L (E) interstitial volume is 12.5 L

Answer 20

C.

10 x .08 = .8 g / .2 = 1g of mannitol

Question 21

Bartter syndrome
Gitelman syndrome
Liddle Syndrome

Answer 21

Bartter syndrome (AR) – Reabsorptive defect of NaCl in the thick ascending loop of Henle. Like loop diuretic effect

Gitelman syndrome (AR)- Reabsorptive defect of NaCl in DCT. Like thiazide diuretics effect. Less severe than Bartter syndrome.

Liddle syndrome (AD) - Gain of function mutation of Na+ channelà Increased Na+ reabsorption in collecting duct. Results in hypertension. Treatment: Amiloride (K+ sparing)

Bartter and Gitelman mutations, like specific diuretics, promote delivery of increased NaCl to the collecting duct. In the CT increased Na+ absorption leads to K+ loss from the principal cell. Liddle directly increases Na+ absorption, which leads to increased K+ loss. K+ is reabsorbed in α- intercalated cells at expense of H+ secretion > metabolic alkalosis.

*These are renal tubular defects causing metabolic alkalosis, all chloride resistant

Question 22

A 72-year-old woman with a history of mild heart failure comes to the physician because of bilateral pedal edema. Treatment with a thiazide diuretic is begun. Three days later, she returns to the physician because of muscle weakness. Laboratory studies show a potassium of 2.8 mEq/L (nl 3.5-5.0). An ECG shows decreased amplitude and broadening of T waves, prominent U waves, and premature ventricular contractions. Which of the following is most likely increased in this patient?
A. Arterial H + concentration B. Plasma aldosterone C. Plasma sodium D. Plasma potassium E. Potassium retention

Answer 22

Diuretic induced volume depletion stimulates the formation of angiotensin II which in turn causes a secondary increase in plasma aldosterone concentration. This increase in plasma aldosterone stimulates potassium excretion, contributing to the hypokalemia,. Also the saline diuresis increases sodium delivery to the collecting tubule. The increased availability of sodium along with the elevated plasma aldosterone augments sodium reabsorption and potassium secretion in the collecting tubule. Finally aldosterone increases proton loss from the alpha intercalated cells leading to metabolic alkalosis

Question 23

A 23-year-old man is brought to the emergency department with progressive weakness and confusion. He also complains of recent polyuria and polydipsia. He has lost weight over the last 2 weeks, and his urine has a strong fruity odor. His blood pressure is 100/68 mm Hg and his pulse is 112/min. Laboratory results are as follows: Sodium 135 Potassium 3.6 Chloride 100 Bicarbonate 12 Creatinine 1.2 Glucose 498 pH 7.27 PCO2 = 40

Based on the laboratory findings, which of the following is most likely occurring in this patient?
A. Increased serum lactate levels B. Respiratory insufficiency C. Renal tubular acidosis D. Low plasma renin activity E. Adrenal insufficiency

Answer 23

23 anion gap
Predicted PCo2 - 24-28
You should have kussmal respiration

You have respiratory insufficiency + diabetic ketoacidosis.

This could be patient on narcotics who is diabetic. Respiratory drive is repressed with DKA.

fruity odor is smell of acetone with some aromatic amino acids. Acetone is nail polish removed. DKA -
not lactic acidosis, he has ketoacidosis. Lactic acidosis will be poor tissue perfusion

Question 24

Renal tubular acidosis:

Distal renal tubular acidosis (type 1)

Answer 24

Renal Tubular Acidosis – disorder of renal tubules leading to normal anion gap (hyperchloremic) metabolic acidosis

Distal renal tubular acidosis (type 1) – Defect in ability of α-intercalated cells to secrete H+ > metabolic acidosis. Can’t acidify urine (pH > 5.5) Also α-intercalated cells cannot reclaim K+ resulting in hypokalemia. (K+/H+ exchange)

Causes: autoimmune (lupus), amphotericin B and analgesic toxicity, congenital obstruction of urinary tract

Question 25

Hyperkalemic renal tubular acidosis (type 4)

Answer 25

Hyperkalemic renal tubular acidosis (type 4) – Hypoaldosteronism > hyperkalemia > potassium is going out, hydrogen can’t go out > less intracellular acidity > decreased NH3 synthesis in PCT > decreased urine buffering of H+, urine pH <5.5 (because there is no buffer in the urine)
Causes: diabetic hyporeninism, ACE inhibitors, ARBs, NSAIDs, hypoaldosteronism, K+-sparing diuretics

Question 26

Proximal renal tubular acidosis (type 2)

Answer 26

Proximal renal tubular acidosis (type 2) – Defect in PCT HCO3- reabsorption > decreased HCO3- reabsorption > serum bicarb drops and subsequent metabolic acidosis. Urine is normally acidified by alpha-intercalated cells in collecting tubule so acidosis less severe. Urine pH <5.5. Associated with other PCT defects such as hypophosphatemia and hypokalemia.
Causes: Fanconi syndrome and carbonic anhydrase inhibitors

Question 27

what effect does too much NSAID ingestion do to potassium serum levels

Answer 27

NSAIDs lower renal renin secretion, which is normally mediated in part by locally produced prostaglandins and they impair angiotensin II-induced aldosterone release.
Thereby similar to aldosterone antagonists, there is decreased potassium excretion leading to hyperkalemia!

Question 28

Vomiting or nasogastric suction is, however, often accompanied by hypokalemia long before this magnitude of gastric fluid losses has occurred. How can you account for the development of hypokalemia from gastric fluid losses?

Answer 28

Usually accompanied by a metabolic alkalosis.

The alpha intercalated cells allow potassium to be excreted in return for conserving sodium.

Question 29

Is URINARY potassium low or high in these states

a. hyperkalemia due to spironolactone (an aldosterone antagonist)
b. hypokalemia due to hydrochlorothiazide or furosemide (both
c. hypokalemia due to diarrhea
*d. a stable patient with moderate renal failure (creatinine 3 diuretics)
mg/dl) due to diabetes (well-controlled on insulin) and hyperkalemia
e. hyperkalemia due to adrenal insufficiency

Answer 29

a. hyperkalemia due to spironolactone (an aldosterone antagonist)
- hypokaluria - no aldosterone effect on the (potassium - sodium exchange in the collecting duct)

b. hypokalemia due to hydrochlorothiazide or furosemide (both diuretics) - hyperkaluria
c. hypokalemia due to diarrhea - you are losing potassium so your body will try to conserve, - hypokaluria

*d. a stable patient with moderate renal failure (creatinine 3)
mg/dl) due to diabetes (well-controlled on insulin) and hyperkalemia - hypokaluria
hypoaldosteronism, RTAcidosis (can’t secrete potassium or organic acids
e. hyperkalemia due to adrenal insufficiency - hypokaluria - hypoaldosteronism

Question 30

patient with diabetes insipidus with a maximal URINE osmolality of 100 mOsm/L. A patient complains of having to pass urine four to five times each night. Can you think of a way to minimize the nocturia without using any drugs?

Answer 30

Put them on a low protein, low salt diet.

example

1000 mOsm / 100 mosm/L= 10 L water excreted

if you decrease the mOsm, then less water would need to be excreted

Question 31

Do you think that measurement of urinary sodium and chloride may be helpful in differentiating the following causes of hyponatremia?

a. SIADH
b. diarrhea due to ulcerative colitis in a man with orthostatic hypotension
c. a woman with primary biliary cirrhosis who has edema and and ascietes

Answer 31

a. SIADH - not that useful, look at urine osmolarity - normal is around 50-100, in this case itd be like 300-400
b. Diarrhea - represents hypovolemia so RAS system is activated leading to low urinary sodium and chloride
c. Women with primary biliary cirrhosis who has edema and ascited, despite normal total volume, the kidney senses low volume and again, low urinary sodium and chloride.

Question 32

a. the syndrome of inappropriate secretion of ADH (SIADH) b. congestive heart failure c. diuretic use d. renal failure

with the subsequent development of hyponatremia. Where does the defect (or defects) in urinary dilution lie in:

Answer 32

a. collecting duct
b. low blood flow > ADH would go up

c. True volume depleted, ADH would still go up in addition to the sodium loss. (thiazides are NOTORIOUs for hyponatremia, loops diuretics not so much
d. Renal failure: you have tubule defects so you can’t resorb as much but you also won’t have too many problems with the ADH system

Question 33

Starling
forces play a major role in the movement of fluid from the intravascular to the interstitial space. What alteration in these forces favors the development of edema in the following conditions?
a. a marked increase in urinary protein (the nephrotic syndrome)
b. congestive heart failure
c. tying a band around your leg
d. an allergic reaction to a bee sting causing hives and facial
In some renal diseases that cause the nephrotic syndrome, the glomerular filtration rate is actually increased despite the kidney disease. Can you think of how an alteration in Starling forces could account for this?

Answer 33

a. low capillary oncotic pressure (fluid out of capillaries)
b. increased capillary hydrostatic pressure
c. increased capillary hydrostatic pressure
d. capillaries are leaky (increases Kf)

RAAS goes up

Question 34

A child is referred to you for an evaluation of prenatal hydronephrosis. What would be your NEXT diagnostic step?

Answer 34

repeat Ultrasound, if they have any signs of fever or if their hydronephrosis is severe, get a VCUG.

Put in a catheter and shoot dye into the bladder, and get the patient to pee.

Question 35

You are evaluating a 10-month old infant who is found to have an enlarged right kidney with multiple cysts ranging 9-12 mm in size based on 2 renal U/S. The contralateral kidney has mild hydronephrosis.
Of the following which diagnostic study would be MOST helpful for this infant at this time?
A. A repeat renal U/S
B. Abdominal MRI
C. Abdominal CT
D. Urine Culture
E. VCUG

Answer 35

VCUG

-one kidney isn’t normal, we have to check quickly because you want to prevent any scarring.

Question 36

A 90-year-old man with a history of BPH has the recent onset of increased difficulty urinating. He mentions that he just started taking an OTC nasal decongestant for cold symptoms. Which of the following types of receptors is most likely to be involved in these adverse effects? (A) α1-Adrenergic (B) β2-Adrenergic (C) Nicotinic receptor at the neuromuscular junction (D) Ganglionic nicotinic (E) Serotoninergic

Answer 36

A)

nasal decongestants are alpha agonists