PEDIATRIC NEPHROLOGY 1.2 (AB) Flashcards
What is one of the most common causes of renal failure in young children?
Hemolytic Uremic Syndrome (HUS)
What are the three key microangiopathic changes seen in Hemolytic Uremic Syndrome?
Hemolytic anemia
What is the most common infectious cause of Hemolytic Uremic Syndrome (HUS)?
E. coli infection
What are the laboratory findings in HUS?
Anemia with microangiopathic changes
What defines a probable case of HUS?
Acute HUS diagnosis without clear history of acute or bloody diarrhea in the preceding 3 weeks OR onset within 3 weeks of bloody diarrhea but without confirmed microangiopathic changes
What defines a confirmed case of HUS?
Acute HUS diagnosis meeting lab criteria with onset within 3 weeks after bloody diarrhea episode
What are two common sources of E. coli transmission in HUS?
Undercooked meat
Describe the pathogenesis of HUS in terms of renal damage.
Thickened capillary walls narrow lumen
What causes microangiopathic anemia in HUS?
Mechanical damage to RBCs passing through narrowed vasculature
What causes thrombocytopenia in HUS?
Intra-renal platelet adhesion or damage
What is the typical age group affected by HUS?
<4 years old
What is the usual clinical presentation of HUS?
Gastroenteritis followed by sudden irritability
What is the management for HUS?
Supportive care
In newborns and infants
what are some causes of Renal Vein Thrombosis?
In older children
what are some causes of Renal Vein Thrombosis?
What is the pathogenesis of Renal Vein Thrombosis?
Thrombus forms due to hypoxia
What is the classic clinical manifestation of Renal Vein Thrombosis?
Sudden gross hematuria
What imaging modality can confirm Renal Vein Thrombosis?
Doppler flow studies of the IVC and renal vein
What are the key components of treatment for Renal Vein Thrombosis?
Supportive care
What gene is associated with Autosomal Recessive Polycystic Kidney Disease (ARPKD)?
PKHD1
What does the PKHD1 gene encode?
Fibrocystin
What is the appearance of the kidneys in ARPKD?
Markedly enlarged with innumerable cysts in cortex and medulla
What is the prognosis for infants with ARPKD?
Poor; many do not survive the first year of life
What is the classic clinical presentation of ARPKD in neonates?
Bilateral flank masses
What is Porter facies?
Low set ears
What are some key systemic findings in ARPKD?
Hypertension
What imaging finding strongly suggests ARPKD?
Enlarged hyperechogenic kidneys with poor corticomedullary distinction on ultrasound
What genetic finding supports the diagnosis of ARPKD?
Absence of renal cysts in both parents (autosomal recessive)
What is the role of genetic testing in ARPKD?
Confirms diagnosis
What is the treatment approach for ARPKD?
Supportive care
What is the estimated 10-year survival for children with ARPKD surviving past the first year?
Over 80%
What percentage of children with ARPKD develop ESRD within the first decade?
Over 50%
What is the long-term prognosis for children with ARPKD?
Relatively poor
Upper limit of normal protein excretion in healthy children
150 mg/day
Proteinuria level on urine dipstick: 1+
30 mg/dL
Proteinuria level on urine dipstick: 2+
100 mg/dL
Proteinuria level on urine dipstick: 3+
300 mg/dL
Proteinuria level on urine dipstick: 4+
> 2,000 mg/dL
Causes of false positive proteinuria on dipstick
Highly concentrated urine, gross hematuria, pH >8, chlorhexidine, benzalkonium, phenazopyridine therapy
3 non-pathologic causes of proteinuria
Postural (orthostatic), fever >38.4°C, exercise
Criteria for non-pathologic proteinuria
<1,000 mg/day and not associated with edema or disease
Transient causes of proteinuria
Fever, exercise, dehydration, cold exposure, CHF, seizure, stress
4 main categories of proteinuria causes
Transient, Orthostatic, Glomerular, Tubular
Examples of tubular causes of proteinuria
Tubulointerstitial nephritis (TIN), Wilson’s disease, heavy metal poisoning, Acute Tubular Necrosis (ATN), Polycystic Kidney Disease (PCKD)
Basic work-up for proteinuria (4 tests)
Serum creatinine, 24-hour urinary protein excretion, urine protein/creatinine ratio, serum C3
When is renal biopsy indicated in proteinuria?
Proteinuria >1 g/day, hypertension, or diminished renal function
4 hallmark findings of nephrotic syndrome
Heavy proteinuria, hypoalbuminemia, edema, hyperlipidemia
Most common cause of nephrotic syndrome in children
Minimal Change Disease (85%)
3 histologic types of idiopathic nephrotic syndrome
Minimal Change Disease, Focal Segmental Glomerulosclerosis, Mesangial Proliferative GN
Histologic findings in Minimal Change Disease
Normal LM, effacement of epithelial foot processes on EM
Steroid response rate in Minimal Change Disease
0.95
Steroid response rate in Focal Segmental Glomerulosclerosis
0.2
Histologic findings in Focal Segmental Glomerulosclerosis
Mesangial proliferation, segmental scarring, (+) IgM and C3
Histologic findings in Mesangial Proliferative GN
Diffuse mesangial cell proliferation and increased matrix
Steroid response rate in Mesangial Proliferative GN
0.5
Pathophysiology of proteinuria in nephrotic syndrome
Increased glomerular capillary permeability
Pathophysiology of Minimal Change Disease
T cell dysfunction alters cytokines, loss of negatively charged glycoprotein in glomerular wall
Main cause of hypoalbuminemia in nephrotic syndrome
Urinary protein loss
Effect of hypoalbuminemia on fluid balance
Decreased plasma oncotic pressure causes fluid transudation to interstitial space
Effect of hypoalbuminemia on renal perfusion
Decreased intravascular volume decreases renal perfusion, activates RAAS
Why does edema worsen in nephrotic syndrome?
ADH release enhances water reabsorption in collecting ducts
2 causes of hyperlipidemia in nephrotic syndrome
Increased hepatic protein synthesis, decreased lipoprotein lipase activity
Why are serum lipids elevated in nephrotic syndrome?
Lipids are bound to albumin, low albumin causes hyperlipidemia
Common demographic for nephrotic syndrome
Males 2-6 years old
Classic presentation of nephrotic syndrome
Generalized edema, anorexia, irritability, abdominal pain
Are hypertension and gross hematuria common in nephrotic syndrome?
No, they are uncommon
Typical urine dipstick finding in nephrotic syndrome
3+ to 4+ proteinuria
Diagnostic protein excretion rate in nephrotic syndrome
> 40 mg/m²/hr
Serum albumin level in nephrotic syndrome
<1.5 g/dL
Serum cholesterol and triglyceride levels in nephrotic syndrome
Elevated
C3 and C4 levels in nephrotic syndrome
Usually normal
Most common infectious complication in nephrotic syndrome
Spontaneous bacterial peritonitis (SBP)
Most common organisms causing infection in nephrotic syndrome
Streptococcus pneumoniae, E. coli
Treatment components for nephrotic syndrome
Low sodium diet, fluid restriction, diuretics, human albumin, steroids, immunosuppressants
Most common cause of UTI in girls
E. coli (75-90%)
Other common UTI pathogens in girls
Klebsiella, Proteus
UTI pathogens in both sexes
Staphylococcus saprophyticus, Enterococcus
Important consideration in male adolescents with UTI
Consider sexually transmitted infections (STDs)
3 clinical forms of UTI
Pyelonephritis, cystitis, asymptomatic bacteriuria
Classic symptoms of pyelonephritis
Abdominal, flank, or back pain, fever, malaise, N/V, diarrhea
Classic symptoms of cystitis
Gross hematuria, dysuria, urgency, frequency, malodorous urine, suprapubic pain
Definition of asymptomatic bacteriuria
Positive urine culture without clinical symptoms
Main pathogenesis of UTI
Ascending infection from fecal flora
Proper genital hygiene technique in girls
Wipe front to back
Urine culture criteria for UTI diagnosis (Nelson’s)
> 100,000 cfu/mL single pathogen OR >10,000 cfu/mL with symptoms
Presumptive UTI criteria
Positive urinalysis, symptoms, and single organism >100,000 cfu/mL
Gold standard for UTI diagnosis (PPS guidelines)
Any bacterial growth from suprapubic aspiration
UTI diagnosis criteria from catheterized urine
> 50,000 cfu/mL single pathogen
UTI diagnosis criteria from midstream void
> 100,000 cfu/mL single pathogen if symptomatic
Imaging test for 1st febrile UTI
Renal ultrasound (UTZ)
Imaging test for 2nd febrile UTI after negative workup
Voiding cystourethrography (VCUG)
Antibiotics for acute cystitis
TMP-SMX, Nitrofurantoin, Amoxicillin (3-5 days)
Antibiotics for clinical pyelonephritis
Ceftriaxone, Cefotaxime, Ampicillin
Best scan for diagnosing acute pyelonephritis
DMSA renal scan
