PEDIATRIC NEPHROLOGY 1.2 (AB) Flashcards by Shiela Micah Gascon

What is one of the most common causes of renal failure in young children?

Hemolytic Uremic Syndrome (HUS)

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What are the three key microangiopathic changes seen in Hemolytic Uremic Syndrome?

Hemolytic anemia

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What is the most common infectious cause of Hemolytic Uremic Syndrome (HUS)?

E. coli infection

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What are the laboratory findings in HUS?

Anemia with microangiopathic changes

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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

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What defines a confirmed case of HUS?

Acute HUS diagnosis meeting lab criteria with onset within 3 weeks after bloody diarrhea episode

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What are two common sources of E. coli transmission in HUS?

Undercooked meat

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Describe the pathogenesis of HUS in terms of renal damage.

Thickened capillary walls narrow lumen

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What causes microangiopathic anemia in HUS?

Mechanical damage to RBCs passing through narrowed vasculature

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What causes thrombocytopenia in HUS?

Intra-renal platelet adhesion or damage

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What is the typical age group affected by HUS?

<4 years old

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What is the usual clinical presentation of HUS?

Gastroenteritis followed by sudden irritability

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What is the management for HUS?

Supportive care

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In newborns and infants

what are some causes of Renal Vein Thrombosis?

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In older children

what are some causes of Renal Vein Thrombosis?

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What is the pathogenesis of Renal Vein Thrombosis?

Thrombus forms due to hypoxia

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What is the classic clinical manifestation of Renal Vein Thrombosis?

Sudden gross hematuria

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What imaging modality can confirm Renal Vein Thrombosis?

Doppler flow studies of the IVC and renal vein

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What are the key components of treatment for Renal Vein Thrombosis?

Supportive care

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What gene is associated with Autosomal Recessive Polycystic Kidney Disease (ARPKD)?

PKHD1

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What does the PKHD1 gene encode?

Fibrocystin

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What is the appearance of the kidneys in ARPKD?

Markedly enlarged with innumerable cysts in cortex and medulla

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What is the prognosis for infants with ARPKD?

Poor; many do not survive the first year of life

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What is the classic clinical presentation of ARPKD in neonates?

Bilateral flank masses

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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