nelson essential

Question 1

What is needed for normal renal function?

Answer 1

1. intact flomerular filtration - regulated by pressure, arterial tone, renin played a part in it
2. intact tubular function: includes the proximal tubule, loop of hence and distal tubule
   to result in urine formation

Question 2

What does the proximal tubule do?

Answer 2

isosmotic reabsorption

• reabsorbs 2/3 of filtered volume, sodium and chloride
• almost completely reabsorbes glucose, amino acids, potassium and phosphate
• reabsorb 75% of bicarbonate - where it exceeds the threshold, it gets spilled into the urine
• also secretes organic acids, penicillins, other drugs

Question 3

which part of the kidney makes calcitriol

Answer 3

proximal tubule cells make calcitriol (aka 1,25 OH2) in response to PTH and intracellular Ca/PO4 concentrations

Question 4

what happens in the loop of Henle

Answer 4

reabsorb NaCl (25%) of what is filtered in the glomerulus 
active chloride transport makes the gradient needed to concentrate urine

Question 5

What does the distal tubule do

Answer 5

includes

1. distal convoluted tubule : active sodium absorption, helps to dilute urine
2. collecting ducts -
   - primary site of ADH response
   - aldosterone regulates Na/K and Na/H exchange
   - active H ion secretion to acidify the urine

Question 6

What is the urinary anion gap?

Answer 6

measures the renal ammonia production - the gap between measured anions and cations are largely of NH4
normal urinary gap is 1meq/kg body weight

Question 7

cause of decreased urinary anion gap

Answer 7

problems with renal acid excretion or ammonia production

Question 8

true or false - preterm newborns are less capable to concentrate urine than term newborns?

Answer 8

true
their maximum urinary concentrating capacity is only 400 mosm/L (vs 600-800 mosm/L for full-term newborn) , which is less than in older children and adults

Question 9

why are infants less capable to excrete a water load than adults

Answer 9

because lower GCF (although they can dilute urine similar to adults )

Question 10

when does GFR reach adult levels

Answer 10

age 1-2
GCF in newborn is 40 ml/min/1.73m2
in adult 100-120 ml/min/1.73 m2

neonate can absorb Na efficiently ASAP, but takes 2 years for bicarb

Question 11

Differential of flank mass in neonate

Answer 11

1. multicystic dysplasia
2. urinary tract obstruction (hydronephrosis)
3. polycystic disease
4. tumor

Question 12

Differential of hematuria in a neonate

Answer 12

1. acute tubular/cortical necrosis
2. Urinary tract malformation
3. trauma
4. renal vein thrombosis

Question 13

Differential of anuria/oliguria in a neonate

Answer 13

1. renal agenesis
2. obstruction
3. acute tubular necrosis
4. vascular thrombosis

Question 14

creatinine affected by which

Answer 14

mucle mass, age (plasma creatinine )

Question 15

BUN affected by which

Answer 15

hydration, nutrition, catabolism, tissue breakdown

Question 16

cause of false positive nitrite test

Answer 16

prolonged contact (ie uncircumsied)
gross hematuria

Question 17

measure of proteinuria

Answer 17

protein/creatinine ratio - very good approximation of 24 hour protein clearance
2.0 in children

Question 18

nephrotic proteinuria

Answer 18

urine protein/creatinine >2.0 or 24 hour protein 40 mg/m2/hour
(normal is <4 mg/m2/hour)

Question 19

Definition of nephrotic syndrome

Answer 19

1. heavy proteinuria (mainly albumin)
2. hypoptroteinemia (albumin 250 mg/dL) (- elevated cholesterol/TG
3. edema

**renal blood flow and GFR not usually diminished, rather get change in oncotic pressure and fluid shifts

Question 20

Causes of primary nephrotic syndrome

Answer 20

1. Minimal change disease - most common, in >80% of children 35% of these kids progress to renal failure
2. Membranoproliferative glomerulonephritis - low complement with signs of glomerular renal disease , 5-15%, usually persistent, high likelihood of renal failure
3. membranous nephropathy - <5%, in teens, with systemic infections/meds

Question 21

teenager with nephrotic syndrome, has hep B, what type of nephrotic syndrome most likely?

Answer 21

membranous nephropathy

occurs in teens/kids with systemic infection - i.e. hepatitis B, syphilis, malaria, todo or on gold/penicillamine

Question 22

What is congenital nephrotic syndrome

Answer 22

presents in first 2 months of type
2 common type - #1: Finnish type, autosomal recessive, mutation in nephron
#2: heterogeneous group of abnormalities
prenatal onset - elevated levels of maternal alpha-fetoprotein
Treatment of familial congenital nephrotic syndrome: early nephrectomy, dialysis and transplantation

Question 23

Name some secondary causes of nephrotic syndrome in kids

Answer 23

SLE
HSP/Wegener/other vasculitides
chronic infections 
allergic reactions
diagetes
amyloidosis
malignancies
CHF, pericarditis
renal vein thrombosis

Question 24

Clinical presentation of nephrotic syndrome

Answer 24

sudden onset pitting edema/ascites - most common
can get anorexia, malaise, abdo pain
BP can be elevated in up to 25%
diarrhea (intestinal edema) and resp distress (pulmonary edema/pleural effusion) can occur

Question 25

Typical minimal change disease - clinical characteristics

Answer 25

``` no hematuria (can occasionally have microscopic hematuria in MCNS) normal BP normal complement (if low suggests other cause than minimal change, also if low should do renal biopsy) ```

Question 26

Differential of proteinuria

Answer 26

1. transient proteinuria - after vigrous exercise, fever, dehydration, seizures, adrenergic agonist therapy; usually mil (urine protein/cr <1), glomerular in origin, always resolves in few days. 2. postural (orthostatic proteinuria) - normal protein exertion when laying down but significant when upright (can also have tubular or glomerular proteinuria)

Question 27

Treatment of nephrotic syndrome

Answer 27

>80% of children with nephrotic syndrome who are t work to relieve the edema, cautious admin of 25% albumin with loop diuretic can help HTN treat with beta blockers/Ca channel blockers, ACEi for persistent

Question 28

Complications of nephrotic syndrome

Answer 28

1. infections - bacteremia and peritonitis - Strep pneumo, E. coli, Klebsiella -since have urinary loss of immunoglobulins and complement 2. hyper coagulable state - since lose antithrombin/plasminogen - risk of thromboembolism - sometimes may need blood thinner 3. increased atherosclerotic vascular disease from hyperlipidemia can also get SEs of steroids, hypovolemia (from diarrhea/diuretic)

Question 29

Prognosis of nephrotic syndrome

Answer 29

most go to remission , 80% with MCNS can have relapse (heavy proteinuria >3 days) can have transient proteinuria with infection, not considered relapse FSGS - can progress to kidney failure

Question 30

Microscopic hematuria -

Answer 30

>3-5 RBC/HPF on fresh urine, often benign can have isolated asymptomatic microscopic hematuria in 4% of healthy children usually it is transient

Question 31

Ddx of hematuria

Answer 31

1. factitius - non pathologic: ie urate cystals, ingested foods, medications, dyes (ie will be negative on urinalysis); pathologic (i.e. hemoglobinuria from hemolytic anemia, myoglobin from rhabdo) 2. glomerular - immunological (ie GN - PSGN, IgA, membranoproliferative GN, systemic disease ), structural (Alport, Bm disease), toxin (ie HUS) 3. Tubulointerstitial/parenchymal 4. lower urinary tract (UTI, trauma/kidney stone, hypercalciuria)

Question 32

Features of acute post streptococcal glomerulonephritis

Answer 32

``` hematuria - gross or microscopic proteinuria hypertension edema oliguria renal insufficiency age: 2-12 year old more in boys usually 5-21 days (mean 10 days) after strep pharyngitis infection and 4-6 weeks after impetigo ```

Question 33

acute post infections GN

Answer 33

same as post strep GN but with other infections - can happen regardless of whether the kid gets antibiotics

Question 34

treatment priorities in GN

Answer 34

take care of BP! can cause heart failure, seizures, encephalopathy treatment is supportive, involves sodium restriction, diuretics and BP meds as needed treating strep doesn't prevent PSGN - should still treat with antibiics if active strep infection occasionally use steroids/other immunosuppression ACEi - might help (but use with caution)

Question 35

Presentation of IgA nephropathy

Answer 35

can vary, acute GN, asymptomatic microscopic hematuria, recurrent gross hematuria CONCURRENT with URTI

Question 36

What is rapidly progressive GN?

Answer 36

typical feutres of acute GN but renal insufficiency progresses more quickly and severely renal biopsy shows crescents can be idiopathic or secondary to knob types of GN

Question 37

What is Alport syndrome

Answer 37

X linked mutation in type IV collagen - leads to abnormal glomerular basement membrane - asymptomatic microscopic or gross hematuria Males: progressive renal failure and sensorineural hearing loss in teens/young adults Females: more benign, but have usually at least microscopic hematuria prognosis: all have end stage renal disease - men in 30s, women later

Question 38

What is benign familial hematuria

Answer 38

autosomal dominant often have hematuria in 1st degree relatives usually the renal disease is not progressive, have good prognosis

Question 39

Painless gross hematuria

Answer 39

sickle cell, Wilms, strenuous exercise

Question 40

What is nutcracker syndrome?

Answer 40

can be a cause of hematuria (with or without pain) - from the compression of the renal vein between other "stuff"

Question 41

hematuria with low complement C3

Answer 41

PSGN membranoproliferative GN lupus nephritis

Question 42

true or false - all gross hematuria should be investigated

Answer 42

true

Question 43

prognosis of post streptococcal GN

Answer 43

usually resolves - within 5-10 days can have microscopic hematuria for months/years- most recover IgA nephropathy more likely to progress

Question 44

findings associated with poor prognosis in glomerulonephritis

Answer 44

1. persistent/heavy proteinuria 2. hypertension 3. decreased kidney function 4. severe glomerula lesions

Question 45

management plan for isolated asymptomatic microscopic hematuria/familial hematuria

Answer 45

usually good prognosis do yearly urinalysis to rule out proteinuria and also do BP yearly (rule out progressive forms of renal disease)

Question 46

What are the findings in hemolytic anemic syndrome?

Answer 46

1. microangiopathic hemolytic anemia 2. thrombocytopenia 3. renal injury

Question 47

age group of most patients with HUS?

Answer 47

usually <5 year old, can happen in older kids

Question 48

What are the prodromal infections most common in HUS?

Answer 48

1. Typical HUS (with diarrhea prodrome): hemorrhagic enterocolitis from verotoxin and then leads to HUS in 5-15% of kids - most common is E. Coli (most commonly E. coli O156: H7, although other strains can also cause ) which can contaminate meat, fruit, veggies or water with verotoxin; Shigella can also cause verotoxin 2. Atypical HUS: - without a diarrhea prodrome - can occur at any age , usually MORE SEVERE than with diarrheal illness prodrome - infection: Strep pneumo, HIV, genetic and acquired defects in complement regulation, meds, malignancy, SLE and pregnancy

Question 49

Causes of atypical HUS (i.e. not with diarrhea)

Answer 49

``` infection - strep pneumo, HIV complement defects (genetic and acquired) medications malignancy SLE pregnancy ```

Question 50

How does HUS present

Answer 50

1. initially have bloody diarrhea 2. 7-10 days later have weakness, lethargy and oliguria/anuria 3. irritable, pallor petechiae 4. dehydration often present, but can have volume overload 5. Hypertension from volume overload or kidney injury 6. CNS involvement - in 25% of cases ; including seizures 7. Other organs: pancreatitis, cardiac dysfunction, colonic perforation

Question 51

Lab findings in HUS

Answer 51

1. Evidence of microangiopathic hemolytic anemia: anemia, thrombocytopenia, shistocytes, helmet cells, burr cells on peripheral blood smear, increased LDH, decreased haptoglobin, increased indirect bill, increased AST, elevated reticulocyte count 2. evidence of renal injury : elevated creatinine; presence of hematuria, proteinuria, pyuria, casts on urinalysis 3. Other - leukocytosis, positive stool culture for E. coli O157: H7; positive stool test for shiga-toxin; elevated amylase/lipase

Question 52

What is TTP?

Answer 52

rare combination of Fever, microangiopathic hemolytic anemia, thrombocytopenia, abnormal renal function and CNS changes - clinically similar to HUS, but usually in older teens/adults get more CNS manifestations (from microvascular thrombi) in the CNS, can also have significant renal disease; can have recurrent episodes

Question 53

What is the mutation in TTP?

Answer 53

most cases are caused by ADAMTS-13 deficiency - responsible for cleaving high molecular weight mol timers of VWF (vs these will be normal in HUS)

Question 54

Coombs test in HUS?

Answer 54

negative

Question 55

stool is negative but you think a kid has HUS?

Answer 55

totally possible, E coli might be gone by the time HUS is diagnosed

Question 56

Treatment of HUS

Answer 56

1. volume repletion 2. control hypertension 3. manage complications of renal insufficiency - including dialysis

Question 57

Should you transfuse platelets in HUS?

Answer 57

no, because they may only add to the thrombotic microangiopathy should only do if active hemorrhage or in anticipation of a procedure

Question 58

Antibiotics for diarrheal illness and antidiarrheal agents- what do they do to the risk of HUS?

Answer 58

they might increase the risk of HUS

Question 59

what intervention in the diarrheal phase of HUS might reduce the severity of renal insufficiency?

Answer 59

early hydration | most kids survive the acute phase and recover normal renal function

Question 60

Proteinuria

Answer 60

``` Proteinuria : - protein/creatinine ratio >0.2 - 24 hour protein excretion : 4 mg/m2/hour Nephrotic range: - protein/creatnine ratio: >2 - 40 mg/m2/hour ```