Review – Kaplan Pediatrics: Renal & Urologic Disorders

URINARY TRACT INFECTION (UTI)

A 12-day-old infant presents with fever of 39°C (102°F), vomiting, and diarrhea. On physical examination, the infant appears to be ill and mildly dehydrated.

Epidemiology—UTI more common in boys than in girls until after second year
Etiology—colonic bacteria (mostly coli, then Klebsiella and Proteus; some S. sapro- phyticus)
Types
- Cystitis—dysuria, urgency, frequency, suprapubic pain, incontinence, no fever

(unless very young)

− Pyelonephritis—abdominal or flank pain, fever, malaise, nausea, vomiting, diar- rhea; nonspecific in newborns and infants

Asymptomatic bacteriuria—positive urine culture without signs or symptoms; can become symptomatic if untreated; almost exclusive to girls

Risk factors
- Females:
  - Wiping
  - Sexual activity
  - Pregnancy
- Males—uncircumcised
- Both:

° Vesicoureteral reflux

Toilet-training
Constipation

° Anatomic abnormalities

Diagnosis—urine culture (gold standard)—and UA findings
- Need a proper sample—if toilet-trained, midstream collection; otherwise, supra- pubic tap or catheterization
- Positive if >50,000 colonies/mL (single pathogen) plus pyuria
Treatment
- Lower-urinary tract infection (cystitis) with amoxicillin, trimethoprim-sulfa- methoxazole, or nitrofurantoin (if no fever)
- Pyelonephritis start with oral antibiotics, unless patient requires hospitalization and IV fluids

Follow up
- Do urine culture 1 week after stopping antibiotics to confirm sterility; periodic reassessment for next 1–2 years
- Obtain ultrasound for anatomy, suspected abscess, hydronephrosis, recurrent UTI
- Obtain voiding cystourethrogram (VCUG) in recurrent UTIs or UTIs with com- plications or abnormal ultrasound findings

VESICOURETERAL REFLUX (VUR)

A 2-year-old girl presents with urinary tract infection. She has had multiple urinary tract infections since birth but has never had any follow-up studies to evaluate these infections. Physical examination is remarkable for an ill-appearing child who has a temperature of 40°C (104°F) and is vomiting.

Definition—abnormal backflow of urine from bladder to kidney
Etiology
- Occurs when the submucosal tunnel between the mucosa and detrusor muscle is short or

− Predisposition to pyelonephritis → scarring → reflux nephropathy (hyper- tension, proteinuria, renal insufficiency to end-stage renal disease [ESRD], impaired kidney growth)

Grading
Grade I: into nondilated ureter (common for anyone)
Grade II: upper collecting system without dilatation
Grade III: into dilated collecting system with calyceal blunting
Grade IV: grossly dilated ureter and ballooning of calyces
Grade V: massive; significant dilatation and tortuosity of ureter; intrarenal reflux with blunting of renal pedicles
Diagnosis

– VCUG for diagnosis and grading

– Renal scan for renal size, scarring and function; if scarring, follow creatinine

Natural history
Increased scarring with grade 5 (less so with bilateral 4)
Majority < grade 5 resolve regardless of age at diagnosis or whether it is unilateral or bilateral
With growth, tendency to resolve (lower > higher grades); resolve by age 6–7 years
Treatment
Medical—based on reflux resolving over time; most problems can be taken care of

nonsurgically

Careful ongoing monitoring for and aggressive treatment of all UTIs

– Surgery if medical therapy fails, if grade 5 reflux, or if any worsening on VCUG or renal scan

OBSTRUCTIVE UROPATHY

Definition—obstruction of urinary outflow tract
Clinical presentation

– Hydronephrosis

Upper abdominal or flank pain
Pyelonephritis, UTI (recurrent)
Weak, decreased urinary stream
Failure to thrive, diarrhea (or other nonspecific symptoms)
Diagnosis

– Palpable abdominal mass in newborn; most common cause is hydronephrosis due to ureteropelvic junction obstruction or multicystic kidney disease (less so– infantile polycystic disease)

– Most can be diagnosed prenatally with ultrasound.

– Obtain VCUG in all cases of congenital hydronephrosis and in any with ureteral dilatation to rule out posterior urethral valves

Common etiologies
Ureteropelvic junction obstruction—most common (unilateral or bilateral hydronephrosis)
Ectopic ureter—drains outside bladder; causes continual incontinence and UTIs
Ureterocele—cystic dilatation with obstruction from a pinpoint ureteral orifice; mostly in girls

– Posterior urethral valves:

Most common cause of severe obstructive uropathy; mostly in boys
Can lead to end-stage renal disease
Present with mild hydronephrosis to severe renal dysplasia; suspect in a male with a palpable, distended bladder and weak urinary stream

Diagnosis—voiding cystourethrogram (VCUG)
Treatment
Decompress bladder with catheter
Antibiotics (intravenously)
Transurethral ablation or vesicostomy
Complications
If lesion is severe, may present with pulmonary hypoplasia (Potter sequence)
Prognosis dependent on lesion severity and recovery of renal function

DISEASES PRESENTING PRIMARILY WITH HEMATURIA

Acute Poststreptococcal Glomerulonephritis

A 10-year-old boy presents with Coca-Cola–colored urine and edema of his lower extremities. On physical examination, the patient has a blood pressure of 185/100 mm Hg. He does not appear to be in any distress. His lungs are clear to auscultation, and his heart has a regular rate and rhythm without any murmurs, gallops, or rubs. His past medical history is remarkable for a sore throat that was presumed viral by his physician 2 weeks before.

Note

For diagnosis of glomerulonephritis, you can use streptozyme (slide agglutination), which detects antibodies to streptolysin O, DNase B,

hyaluronidase, streptokinase, and nicotinamide-adenine dinucleotidase.

Etiology

− Follows infection with nephrogenic strains of group A beta-hemolytic strepto- cocci of the throat (mostly in cold weather) or skin (in warm weather)

Diffuse mesangial cell proliferation with an increase in mesangial matrix; lumpy- bumpy deposits of immunoglobulin (Ig) and complement on glomerular base- ment membrane and in mesangium
Mediated by immune mechanisms but complement activation is mostly through the alternate pathway
Clinical presentation
- Most 5–12 years old (corresponds with typical age for strep throat)

− 1–2 weeks after strep pharyngitis or 3–6 weeks after skin infection (impetigo)

Ranges from asymptomatic microscopic hematuria to acute renal failure

– Edema, hypertension, hematuria (classic triad)

Constitutional symptoms—malaise, lethargy, fever, abdominal or flank pain

Diagnosis
- Urinalysis—RBCs, RBC casts, protein 1–2 +, polymorphonuclear cells
- Mild normochromic anemia (hemodilution and low-grade hemolysis)
- Low C3 (returns to normal in 6–8 weeks)

− Need positive throat culture or increasing antibody titer to streptococcal anti- gens; best single test is the anti-DNase antigen

Consider biopsy only in presence of acute renal failure, nephrotic syndrome, absence of streptococcal or normal complement; or if present >2 months after onset

Complications
- Hypertension
- Acute renal failure
- Congestive heart failure
- Electrolyte abnormalities
- Acidosis
- Seizures
- Uremia
Treatment (in-patient, if severe)
- Antibiotics for 10 days (penicillin)
- Sodium restriction, diuresis

Fluid and electrolyte management
Control hypertension (calcium channel blocker, vasodilator, or angiotensin- converting enzyme inhibitor)
Complete recovery in >95%

Other Glomerulonephritides

IgA Nephropathy (Berger disease)

• Most common chronic glomerular disease worldwide

Clinical presentation
- Most commonly presents with gross hematuria in association with upper respira- tory infection or gastrointestinal infection
- Then mild proteinuria, mild to moderate hypertension

– Normal C3

Most important primary treatment is blood pressure

Alport Syndrome

The school nurse refers a 7-year-old boy because he failed his hearing test at school. The men in this patient’s family have a history of renal problems, and a few of his maternal uncles are deaf. A urinalysis is obtained from the patient, which shows microscopic hematuria.

Hereditary nephritis (X-linked dominant); renal biopsy shows foam cells
Asymptomatic hematuria and intermittent gross hematuria 1–2 days after upper respiratory infection
Hearing deficits (bilateral sensorineural, never congenital) females have subclinical hearing loss

• Ocular abnormalities (pathognomonic is extrusion of central part of lens into ante- rior chamber

Membranous Glomerulopathy

Most common cause of nephrotic syndrome in adults

Membranoproliferative Glomerulonephritis

Most common cause of chronic glomerulonephritis in older children and young adults

Lupus Nephritis

Varying clinical presentations
Treatment depends on type of renal disease but usually includes steroids +/– immuno- modulators

Henoch-Schönlein Purpura

Small vessel vasculitis with good prognosis
Present with purpurie rash, joint pain, abdominal pain
Most resolve spontaneously; antiinflammatory medications, steroids

Hemolytic Uremic Syndrome (HUS)

A 3-year-old child presents to the emergency center with history of bloody diarrhea and decreased urination. The mother states that the child’s symptoms began 5 days ago after the family ate at a fast-food restaurant. At that time the patient developed fever, vomiting, abdominal pain, and diarrhea. On physical examination, the patient appears ill. He is pale and lethargic.

• Most common cause of acute renal failure in young children

Microangiopathic hemolytic anemia, thrombocytopenia, and uremia
Most from coli O157:H7 (shiga toxin–producing)
- Most from undercooked meat or unpasteurized milk; spinach
- Also from Shigella, Salmonella, Campylobacter, viruses, drugs, idiopathic
Pathophysiology
- Subendothelial and mesangial deposits of granular, amorphous material—vascular occlusion, glomerular sclerosis, cortical necrosis
- Capillary and arteriolar endothelial injury → localized clotting

− Mechanical damage to RBCs as they pass through vessels

Intrarenal platelet adhesion and damage (abnormal RBCs and platelets then removed by liver and spleen)
Prothrombotic state

Clinical presentation
- Most common <4 years old
- Bloody diarrhea

− 5–10 days after infection, sudden pallor, irritability, weakness, oliguria occur; mild renal insufficiency to acute renal failure (ARF)

Labs—hemoglobin 5–9 mg/dL, helmet cells, burr cells, fragmented cells, moderate reticulocytosis, white blood cells up to 30,000/mm3, Coombs negative, platelets usually 20,000–100,000/mm3, low-grade microscopic hematuria and proteinuria

Many complications, including seizures, infarcts, colitis, intussusception, perforation, heart disease, death
Treatment

− Meticulous attention to fluids and electrolytes

Treat hypertension
Aggressive nutrition (total parenteral nutrition [TPN])
Early peritoneal dialysis
No antibiotics if coli O157:H7 is suspected—treatment increases risk of develop- ing HUS

− Plasmapheresis or fresh frozen plasma—may be beneficial in HUS not associated with diarrhea or with severe central nervous system involvement

Prognosis—more than 90% survive acute stage; small number develop ESRD (end-stage renal disease)

POLYCYSTIC KIDNEY DISEASE

Autosomal-Recessive Type (Infantile)

Both kidneys greatly enlarged with many cysts through cortex and medulla
Microcysts → development of progressive interstitial fibrosis and tubular atrophy

→ renal failure

Also liver disease—bile duct proliferation and ectasia with hepatic fibrosis
Clinical presentation
- Bilateral flank masses in neonate or early infancy

− May present with Potter sequence

Hypertension, oliguria, acute renal failure
About half have liver disease in newborn period

Diagnosis

− Bilateral flank masses in infant with pulmonary hypoplasia (if severe)

Oliguria and hypertension in newborn with absence of renal disease in parents
Ultrasound–prenatal and postnatal (numerous small cysts throughout)

Treatment and prognosis
- Symptomatic
- Now more than 80% with 10-year survival
- End-stage renal failure in more than half

− Need dialysis and transplant

Autosomal-Dominant Type (Adults)

Most common hereditary human kidney disease
Both kidneys enlarged with cortical and medullary cysts
Most present in fourth to fifth decade, but may present in children and neonates
Renal ultrasound shows bilateral macrocysts
Also systemic cysts—liver, pancreas, spleen, ovaries; intracranial (Berry) aneurysm

(rarely reported in children)

• Diagnosis—presence of enlarged kidneys with bilateral macrocysts with affected first-degree relative

Treatment—control of blood pressure (disease progression correlates with degree of hypertension); presentation in older children with favorable prognosis

DISEASES PRESENTING WITH PROTEINURIA

Types of Proteinuria

Transient—from fever, exercise, dehydration, cold exposure, congestive heart failure, seizures, stress

• Orthostatic—most common form of persistent proteinuria in school-aged children and adolescents

Normal to slightly increased proteinuria in supine position but greatly increased in upright

− Rule this out before any other evaluation is done.

Fixed—glomerular or tubular disorders; suspect glomerular in any patient with >1 g/24 hours proteinuria or with accompanying hypertension, hematuria, or renal dysfunction

Nephrotic Syndrome

A 3-year-old child presents to the physician with a chief complaint of puffy eyes. On physical examination, there is no erythema or evidence of trauma, insect bite, cellulitis conjunctival injection, or discharge.

• Steroid-sensitive minimal change disease is the most common nephrotic syndrome seen in children.

Features

− Proteinuria (>40 mg/m2/hour)

Hypoalbuminemia (<2.5 g/dL)
Edema
Hyperlipidemia (reactive to loss of protein)

Minimal Change Disease

Clinical presentation

− Most common between 2 and 6 years of age

May follow minor infections
Edema—localized initially around eyes and lower extremities; anasarca with serosal fluid collections less common
Common—diarrhea, abdominal pain, anorexia
Uncommon—hypertension, gross hematuria
Diagnosis
- Urinalysis shows proteinuria (3–4 +)
- Some with microscopic hematuria

− 24-hour urine protein—40 mg/m2/hour in children but now preferred initial test is a spot urine for protein/creatinine ratio >2

Serum creatinine usually normal but may be increased slightly

− Serum albumin <2.5 g/dL

Elevated serum cholesterol and triglycerides
C3 and C4 normal
Treatment
- Mild—outpatient management; if severe—hospitalize
- Start prednisone for 4–6 weeks, then taper 2–3 months without initial biopsy

− Consider biopsy with hematuria, hypertension, heart failure, or if no response after 8 weeks of prednisone (steroid resistant)

Sodium restriction
If severe—fluid restriction, plus intravenous 25% albumin infusion, followed by diuretic to mobilize and eliminate interstitial fluid
Re-treat relapses (may become steroid-dependent or resistant); may use alternate agents (cyclophosphamide, cyclosporine, high-dose pulsed methylprednisolone); renal biopsy with evidence of steroid dependency
Complications
- Infection is the major complication; make sure immunized against Pneumococcus

and Varicella and check PPD

− Most frequent is spontaneous bacterial peritonitis (S. pneumoniae most common)

Increased risk of thromboembolism (increased prothrombotic factors and decreased fibrinolytic factors) but really with aggressive diuresis

Prognosis
- Majority of children have repeated relapses; decrease in number with age
- Those with steroid resistance and who have focal segmental glomerulosclerosis have much poorer prognosis (progressive renal insufficiency).

MALE GENITOURINARY DISORDERS

Undescended Testes

• Most common disorder of sexual differentiation in boys (more in preterm)

Testes should be descended by 4 months of age or will remain undescended; surgery best performed at 6 months
Usually in inguinal canal, but some are ectopic
Prognosis
- Treated:
  - Bilateral—50–65% remain fertile
  - Unilateral—85% remain fertile

– Untreated or delay in treatment—increased risk for malignancy (seminoma most common)

• Surgery (orchiopexy) at 9–15 months

Testicular Torsion

Most common cause of testicular pain over 12 years old
Clinical presentation—acute pain and swelling; tenderness to palpitation
Testicle in transverse lie and retracted, no cremateric reflex