Pediatric Examination and Board Review (222 page)

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2005;20;1269-1272.

Gardner-Medwin JM, Dolezalova P, Cummins C, Southwood TR. Incidence of Henoch-Schönlein purpura, Kawasaki disease, and rare vasculitides in children of different ethnic origins.
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2002;360:1197-1202.

Habib R, Niaudet P, Levy M. Henoch-Schönlein purpura nephritis and IgA nephropathy. In: Tisher CC, Brenner BM, eds.
Renal Pathology with Clinical and Functional Correlations
. Philadelphia, PA: Lippincott; 1993:472.

Kauffmann RH, Herrmann WA, Meyer CJ, et al. Circulating IgAimmune complexes in Henoch-Schönlein purpura. A longitudinal study of their relationship to disease activity and vascular deposition of IgA.
Am J Med.
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Levy M, Broyer M, Arsan A, Levy-Bentolila D, Habib R. Anaphylactoid purpura nephritis in childhood: natural history and immunopathology.
Adv Nephrol Necker Hosp.
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Meadow SR. Henoch-Schönlein syndrome. In: Edelmann CM, ed.
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Saulsbury FT. Henoch-Schönlein purpura in children. Report of 100 patients and review of the literature.
Medicine
(
Baltimore
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Trapani S, Micheli A, et al. Henoch Schonlein purpura in childhood: epidemiological and clinical analysis of 150 cases over a 5-year period and review of literature.
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2005;35:135-137.

CASE 129: A 10-YEAR-OLD GIRL WITH BED-WETTING AND PROTEINURIA

A 10-year-old African American girl is being evaluated for bedwetting. She had been dry during the day since age 2 years but is wet every night. A urinalysis was performed as part of the evaluation for enuresis. It demonstrated 3+ proteinuria with an occasional RBC/HPF.

She denied symptoms of periorbital, pedal, or pretibial edema; there was no history of arthralgias, headaches, dizziness, UTI, or rash. Her father was known to have proteinuria and is being evaluated for it.

On physical examination this healthy-appearing 10-year-old weighed 46.3 kg, measured 61.3 cm in length, and had blood pressure 122/78 mm Hg. The chest was clear to auscultation, and there was no evidence of peripheral edema. The abdominal evaluation was normal. There was no rash.

The laboratory examination reveals a urinalysis with specific gravity 1.018, pH 6.5, protein 3+, 3-5 WBC/HPF, and occasional RBC/HPF. The urinary protein-to-creatinine ratio is 3.5. The BUN is 10 mg/ dL, serum creatinine 0.7 mg/dL, total protein 6.7 g/ dL, albumin 3.7 g/dL, and cholesterol 158 mg/dL. The C
₃
level is 110 mg/dL and the ANA is less than 1:40.

SELECT THE ONE BEST ANSWER

1.
Regarding her proteinuria, the next test that should be ordered is

(A) renal ultrasound

(B) creatinine clearance

(C) 24-hour urinary protein excretion

(D) first voided sample for protein-to-creatinine ratio

(E) a renal biopsy

2.
The morning urinary protein-to-creatinine ratio was 3.0 (normal is <0.2). A likely cause of asymptomatic fixed proteinuria in a 9- to 10-year-old girl with enuresis is

(A) minimal change nephrotic syndrome

(B) reflux nephropathy

(C) focal segmental glomerulosclerosis

(D) membranoproliferative glomerulonephritis

(E) nephrogenic diabetes insipidus

3.
The renal ultrasound and voiding cystourethrogram are normal. The pediatric nephrologist performs a percutaneous renal biopsy. The most likely tissue diagnosis is

(A) focal segmental glomerulosclerosis

(B) minimal change nephrotic syndrome

(C) membranoproliferative glomerulonephritis

(D) membranous nephropathy

(E) normal

ANSWERS

1.
(D)
Although this patient with asymptomatic proteinuria had a random protein-to-creatinine ratio of 3.5, one should always exclude orthostatic proteinuria before proceeding to a more complicated evaluation. The long-term prognosis for orthostatic proteinuria is excellent. The urinary protein-to-creatinine ratio is commonly used in pediatrics because it is difficult to collect an accurately timed specimen. Also, 24-hour collections may yield an increased protein concentration even in orthostatic proteinuria. Because creatinine is a byproduct of muscle metabolism that is produced and excreted at a constant rate, the ratio of total protein (or any other substance) to creatinine is constant and reproducible regardless of whether the urine is concentrated or dilute.

2.
(B)
Reflux nephropathy can be diagnosed with a renal ultrasound that shows irregular contours and thinned cortex, along with frequently dilated ureters. A VCUG most likely will demonstrate vesicoureteral reflux (see Case 119). The natural history of low grade reflux is that it improves with time, but if reflux is severe enough to cause nephropathy, it will likely persist. Hypertension is often present with reflux nephropathy. Minimal change, focal segmental glomerulosclerosis, and membranoproliferative glomerulonephritis often present with heavy proteinuria but patients with these disorders usually have less primary nocturnal enuresis. All require percutaneous renal biopsy for diagnosis. Nephrogenic diabetes insipidus does reflect an inability of the kidney to concentrate the urine in response to DDAVP but is not usually associated with proteinuria.

3.
(A)
Focal segmental glomerulosclerosis is the most common finding on biopsy in such patients, especially African Americans, who have asymptomatic, isolated, fixed proteinuria. Minimal change and membranous nephropathy present with symptomatic nephrotic syndrome. Membranoproliferative glomerulonephritis may or may not be associated with the nephrotic syndrome but is associated with hematuria and low complement. FSGS in the context of asymptomatic proteinuria has a much better prognosis than in patients who have steroidresistant nephrotic syndrome and biopsy-proven FSGS. This patient with only moderate proteinuria and FSGS was successfully treated with cyclosporine, and the protein-to-creatinine ratio decreased to 0.56.

S
UGGESTED
R
EADING

Hogg RJ, Portman RJ, Milliner D, et al. Evaluation and management of proteinuria and nephrotic syndrome in children: recommendations from a pediatric nephrology panel established at the National Kidney Foundation Conference on Proteinuria, Albuminuria, Risk, Assessment, Detection and Elimination (PARADE).
Pediatrics.
2000;105:1242-1249.

Houser MT, Jahn MF, Kobayashi A, Walburn J. Assessment of urinary protein excretion in the adolescent: effect of body position and exercise.
J Pediatr.
1986;109:556-561.

Roy S 3rd, Stapleton FB. Focal segmental glomerulosclerosis in children: comparison of nonedematous and edematous patients.
Pediatr Nephrol.
1987;1:281-285.

Rytand DA, Spreiter S. Prognosis in postural (orthostatic) proteinuria: forty to fifty-year follow-up of six patients after diagnosis by Thomas Addis.
N Engl J Med.
1981;305:618-621.

Vehaskari V, Rapola J. Isolated proteinuria: analysis of a schoolage population.
J Pediatr.
1982;101:661-668.

CASE 130: A 15-YEAR-OLD BOY WITH FLANK PAIN AND BLOODY URINE

A 15-year-old Asian American adolescent boy presented to the emergency department with right flank pain and otherwise painless gross hematuria. The patient is adopted, and his adoptive parents were unaware of any family history of renal disease or nephrolithiasis. The past medical history was unremarkable except for seasonal allergies.

On physical examination this healthy-appearing 15-year-old weighed 61.5 kg, measured 169 cm in height, and had a blood pressure of 140/90 mm Hg. The chest was clear to auscultation, and there was no evidence of peripheral edema. The abdominal examination was normal. The laboratory tests revealed a urinalysis with a specific gravity 1.010, pH 8, 3+ proteinuria, 10-20 WBC/HPF, and more than 20 RBC/HPF. The urinary protein-tocreatinine ratio was 0.23 (normal <0.2) and the calciumto-creatinine ratio was 0.09 (normal < 0.21). The urine culture was negative.

The BUN was 13 mg/dL, serum creatinine 0.9 mg/ dL, and Hgb 16.1 g/dL. The serum C3 level was 131 mg/dL (83-177 for adults), C
₄
44 mg/dL (15-45 for adults), and the antistreptolysin O antibody less than 200 IU/mL. The patient was referred to the pediatric renal clinic after acute nephrolithiasis was ruled out on imaging.

SELECT THE ONE BEST ANSWER

1.
In the evaluation of hematuria with absent or minimal proteinuria, the most important part of the evaluation is

(A) history

(B) physical examination

(C) urinary calcium-to-creatinine ratio

(D) CT scan

(E) renal biopsy