Renal, Water/Electrolytes and GU

Question 1

Clinical triad in renal vein thrombosis

Answer 1

Hematuria

Flank mass

Thrombocytopenia

Can propagate from origin in small renal veins to IVC

Question 2

Mechanism of hypertension in renal artery thrombosis

Answer 2

Release of renin as a response to renal hypoperfusion from the clot

Question 3

Initial trigger for renin release

Answer 3

Decreased renal perfusion pressure

Question 4

Renin ultimately stimulates ___ in the lungs to make more ____

Answer 4

1. ACE— throughout body, but highest in vascular endothelium of lungs.
2. Angiotensin II—potent vasoconstrictor

Question 5

Effects of angiotensin II (immediate and if sustained)

Answer 5

Vasoconstriction

Vascular hyperplasia and hypertrophy

(Reason ACEI can help with preventing long term sequelae if vascular injury/hypertension is prolonged)

Question 6

Two downstream proteins after Angiotensin II and their effects

Answer 6

Angiotensin III—aldosterone secretion, increases sodium retention and therefore blood volume/fluid overload

Angiotensin IV—increases blood viscosity

Question 7

ACEI mechanisms

Answer 7

1. Decreases ACE activity (lungs)—less angiotensin II that causes vasoconstriction
2. Less angiotensin II/III: less aldosterone and decreased vasoconstriction
3. Less bradykinin/kallidin activity (vasoactive peptides)
4. Long-term, prevents vascular remodeling

Question 8

Beta blocker mechanisms

Answer 8

1. Decreased HR
2. Decreased stroke volume
3. Decreases renin secretion

Question 9

Spironolactone mechanism

Answer 9

Blocks aldosterone receptor

Question 10

Location of:

1. Angiotensinogen synthesis
2. Conversion to Angiotensin I
3. Conversion to Angiotensin II

Answer 10

1. Liver
2. Kidneys (in response to renin)
3. Lung (high concentration of ACE in pulmonary vascular endothelium)

Question 11

Most common abdominal mass in female neonates

Answer 11

Simple ovarian cyst

“Simple” can have >1 THIN-walled septated region

Thick walls or heterogenous echogenecity means it’s complex (potential torsion/necrosis)

Question 12

Potter’s sequence findings

Answer 12

Oligohydramnios, arthrogryposis, pulmonary hypoplasia, face with beaked nose, wide-set eyes, low-set ears

Question 13

Triad of Eagle-Barrett Syndrome

Answer 13

I.e. prune belly syndrome

Absent/hypoplastic abdominal musculature

Cryptorchidism

Renal dysplasia with megaureter and poorly contractile, distended bladder

Question 14

Ultrasound findings in posterior urethral valve

Answer 14

Megaureters with a thickened, trabeculated bladder (because it’s been pushing against the dysfunctional urethral valve)

Question 15

Which of the congenital cystic kidney disorders carries the worst prognosis?

Answer 15

Autosomal recessive polycystic kidney disease (ARPKD)

70% survival in neonatal period

50% develop renal failure in childhood

Question 16

Findings in renal artery thrombosis

Answer 16

Hypertension (if mild/moderate)

Conjugated hyperbilirubinemia

Thrombocytopenia

Hematuria

Question 17

Which has a higher morbidity/mortality, renal artery or vein thrombosis?

Answer 17

Renal artery thrombosis–10-20% mortality if involves aorta, hypertension common

Question 18

Treatment for renal artery vs. renal vein thromboses

Answer 18

RAT–systemic heparinization (when moderate/severe)

RVT–supportive care (electrolyte corrections, avoidance of further injury)

(RAT treatment is intensive because outcomes if persists are worse)

Question 19

Definition of stage 3 AKI (acute kidney injury)

Answer 19

Serum creatinine >3x baseline and/or urine output (UOP) = 0.3ml/kg/h

Question 20

FeNa and types of renal injury

Answer 20

FeNa (fraction excreted Na)= (uNa x sCr) / (sNa x uCr)

Prerenal: FeNa <1% (because kidneys can still concentrate and hold onto Na)

Acute tubular necrosis (ATN): >2%

uNa goes on top because it’s the fraction in your urine that you’ve peed out

Question 21

Location and mechanism of action of furosemide

Answer 21

Thick ascending loop of Henle (Na-K-2Cl symporter)

Causes decreased Na, K, Cl (Mg and Ca) reabsorption

Less hypertonic medulla, more water excretion

Question 22

Location and mechanism of action of thiazides

Answer 22

Distal convoluted tubule (the Na-Cl cotransporter)

Causes decreased Na, K and Cl reabsorption but INCREASED Ca++

Leads to smaller osmotic gradient so don’t reabsorb water

Question 23

Most common palpable abdominal mass in neonates

Answer 23

Hydronephrosis

Question 24

Studies to consider in multicystic dysplastic kidney (MCKD/MKD)

Answer 24

1. Postnatal ultrasound (30-50% have contralateral renal anomaly)–should be done at 48-72h to decrease false negatives
2. DMSA (dimercaptosuccinic acid/radionuclide scan) if other kidney’s also abnormal
3. Annual renal ultrasound

Question 25

Similar to autosomal recessive polycystic kidney disease (ARPKD), posterior urethral valves often results in end-stage renal disease by \_\_\_\_

Answer 25

10 years ## Footnote ARPKD is the most severe of the cystic kidney diseases PUV is the most severe of the obstructive uropathies

Question 26

Frequent concomitant finding with posterior urethral valves (PUV)

Answer 26

Vesicoureteral reflux (VUR) from malpositioned/ectopic ureteral insertion

Question 27

Non-renal finding associated with autosomal recessive polycystic kidney disease (ARPKD)

Answer 27

Hepatic fibrosis

Question 28

Non-renal findings associated with autosomal dominant polycystic kidney disease (ADPKD)

Answer 28

Cysts in other organs (e.g. spleen and pancreas)

Question 29

Synonym for arginine vasopressin and its location of synthesis

Answer 29

Antidiuretic hormone (ADH) Posterior pituitary (precursor made in hypothalamus) Acts mainly on **collecting duct** and increases aquaporins

Question 30

Primary hormonal determinant of water excretion

Answer 30

ADH (ie. vasopressin) Synthesized in hypothalamus but stored in **posterior pituitary** Acts mainly on collecting duct (also DCT) and increases **aquaporins**

Question 31

Two locations of the V2 receptors

Answer 31

1. DCT 2. Collecting ducts (CD) V2R is predominantly in kidneys, V1R is throughout (vascular smooth muscle, liver, etc) **V2R is robust in neonates, even preemies**

Question 32

Reason for neonatal poor response to ADH

Answer 32

Immaturity of renal ADH-specific adenylate cyclase [in both DCT and collecting ducts] Neonates (even preemies) have many ADH (aka V2) receptors, just can't respond (ADH and AVP are synonyms)

Question 33

Mechanism of action of ADH at the DCT and collecting duct

Answer 33

Stimulates adenylate cyclase--increased cAMP--increased translocation of aquaporins--more water reabsorptive capacity

Question 34

Mechanism of action of ADH at Loop of Henle

Answer 34

Stimulates adenylate cyclase--increased cAMP--active transport of Na into renal medulla--increased osmotic gradient drives water reabsorption

Question 35

Bladder extrophy is more common in ____ and usually associated with \_\_\_\_

Answer 35

Males Inguinal hernia

Question 36

Primary location of sodium reabsorption in the kidney

Answer 36

Proximal tubule (70%) (Followed by 25% in thick ascending limb of loop of Henle, only 5-10% is in DCT and collecting ducts)

Question 37

Primary reason for decreased sodium reabsorption in preemies

Answer 37

**Decreased number of Na-K-ATPase and ion-specific transporters** (everywhere) Even if aldosterone has a normal concentration (which normally is), preemie kidneys have limited transporters to respond (would normally upregulate number as well as activate them)

Question 38

Renin is made in the \_\_\_ Angiotensinogen is made in the \_\_\_ Angiotensinogen is converted to Angiotension I in the \_\_\_ Angiotensin II is made in the \_\_\_\_ Aldosterone is made in the ___ and acts at the \_\_\_\_\_

Answer 38

Kidneys Liver Plasma Lung vasculature (by ACE) Adrenals Cortical collecting ducts (CCD) and DCT

Question 39

Hormonal reason for late (2-6 weeks of age) hyponatremia in preemies

Answer 39

1. Poor response to aldosterone (decreased number but normal function of Na-K-ATPase and other transporters) so increase urine loss

Question 40

Classic laboratory urine findings in premature infants with hyponatremia

Answer 40

High urine sodium and FeNa Kidney can't hold onto Na (and that's aldosterone's job)

Question 41

Primary role of aldosterone

Answer 41

Upregulates and activates sodium transporters in distal tubule (DCT) and collecting duct (CCD) (Important even though PCT and Loop of Henle both are more responsible for Na reabsorption than DCT and CCD)

Question 42

Aldosterone is made in the \_\_\_\_, primarily acts at the ____ by upregulating and activating \_\_\_\_

Answer 42

1. Adrenals 2. Cortical collecting ducts (CCDs) and distal convoluted tubules (DCTs) 3. Na-K-ATPase (pumps) and ENaC channels (cause Na reabsorption)

Question 43

Hormonal reason for early hypernatremia in preemies

Answer 43

Poor response to ADH (adenylate-cyclases in kidneys are present but immature) so lose too much water

Question 44

Which RTA causes a non-anion gap acidosis and a normal (acidic) urine pH

Answer 44

RTA Type _II_: decreased bicarbonate reabsorption in the **_p_**roximal tubule ## Footnote *You **_P_**ee _2_ much _HCO3_*

Question 45

What is the issue in RTA I

Answer 45

Cannot secrete H⁺ in DCT (distal) (Since you can't secrete acid, your urine is alkaline)

Question 46

Type IV RTA is caused by _______ deficiecy

Answer 46

Aldosterone deficiency ## Footnote *Think of CAH--salt wasting, hyperkalemia, acidosis*

Question 47

Draw the nephron, which parts do what, and key associations

Answer 47

Question 48

FeNa indicative of intrinsic renal injury

Answer 48

FeNa \>2-2.5% (depends on source) ## Footnote *Because point of kidney is **reabsorption**, so if injured can't pull Na⁺ back in*

Question 49

If you are highly suspicious of posterior urethral valves, what is the first step in management postnatally

Answer 49

Placement of a foley catheter to relieve the obstruction (Would be suggested by bilateral hydronephrosis, hydroureters, and a thickened/trabeculated bladder)

Question 50

What sodium transporters/channels does aldosterone effect?

Answer 50

DCT: Na-Cl transporter (apical AKA urine side) CCD: ENaC (apical) Both DCT and CCD: Na/K ATPase (bloode side)

Question 51

What is the AT2 receptor most important for?

Answer 51

Found in fetal/preemie kidneys, promotes nephrogenesis (via angiotensin II)

Question 52

The class of antihypertensives to be avoided in preterm infants (and those with acute renal failure)

Answer 52

Angiotensin-converting enzyme inhibitors (ACEI)

Question 53

Nephrogenesis occurs until ____ (GA or PMA)

Answer 53

36 weeks