Pediatric Examination and Board Review (219 page)

Cendron M. Primary nocturnal enuresis: Current concepts.
J Am Fam Physician.
1999;59:1205-1214, 1219-1220.

Husmann D. Enuresis.
Urology.
1996;48:184-193.

Schmitt BD. Nocturnal enuresis.
Pediatr Rev.
1997;18:183-190.

CASE 125: A 6-YEAR-OLD WITH PUFFY EYELIDS AND SWOLLEN LEGS

A 6-year-old Asian American male is admitted for puffiness of the eyelids and swelling of both lower extremities. The illness started 2 weeks before admission with mild puffiness of the eyelids. The eyelid swelling worsened, and 1 week before admission, the patient developed swelling of both lower extremities. The abdomen became protuberant. There is no history of gross hematuria, fever, or anyone in the family receiving regular medications. On physical examination, he was in no acute distress. The temperature was 98.6°F (37°C), heart rate 110/minute, respiratory rate 20/minute, and blood pressure 115/75 mm Hg. The child had anasarca with pitting edema of both lower extremities. The remainder of the physical examination was unremarkable.

The urinalysis revealed a specific gravity of 1.030, pH 5, protein 4+, 5-10 RBC/HPF, 1-2 WBC/HPF, and an occasional coarse granular cast. The BUN was 29 mg/dL. The serum creatinine was 0.8 mg/dL, and the creatinine clearance was 98 mL/minute per 1.73 m
²
. The streptolysin O antibody was less than 200 IU/mL, C
₃
124 mg/dL (88-155 for age). The antinuclear antibody (ANA) was negative, and the spot urine protein-to-urine creatinine ratio was 8. The blood cholesterol was 520 mg/dL; the total protein was 4.6 g/dL, and the serum albumin was 1.2 g/dL.

SELECT THE BEST ANSWER

1.
The urinalysis and blood test data suggest the diagnosis of

(A) acute postinfectious glomerulonephritis

(B) focal segmental glomerulosclerosis (FSGS)

(C) membranoproliferative glomerulonephritis

(D) minimal change nephrotic syndrome

(E) B and D

2.
The specific gravity of the urine is very high because of

(A) heavy proteinuria

(B) intravascular volume depletion

(C) azotemia and increased fractional excretion sodium

(D) A and C

(E) A and B

3.
Which of the following treatments is not indicated at this time?

(A) pneumococcal vaccine

(B) steroids

(C) diphenhydramine

(D) aspirin

(E) HMG-CoA reductase inhibitor

4.
After 14 days of daily prednisone the proteinuria resolved and the patient lost all evidence of edema. Over the next 12 months, 4 relapses of the nephrotic syndrome occurred. This patient is

(A) likely to become steroid resistant

(B) likely to outgrow the disease

(C) at risk of developing chronic renal insufficiency

(D) likely to develop premature atherosclerotic heart disease

(E) A and C

ANSWERS

1.
(E)
This patient has nephrotic syndrome, with heavy proteinuria, low serum albumin, edema, and elevated cholesterol. The 2 most common syndromes in childhood are minimal change nephrotic syndrome (MCNS) and FSGS. They are often clinically indistinguishable at presentation, but MCNS responds to steroids and FSGS rarely does. Responding to steroids remains the best predictor of a good long-term outcome. Twenty percent of patients with MCNS and FSGS have microscopic hematuria. In children with MCNS, 30-40% initially have an elevated serum creatinine, due in part to intravascular hypovolemia. Patients with acute postinfectious glomerulonephritis rarely develop nephrotic syndrome, and like MPGN, this disease is usually associated with a low C
₃
level.

2.
(B)
Proteins, especially albumin, have high molecular weights. Therefore heavy proteinuria does not contribute significantly to specific gravity, which is a reflection of osmolality and the contribution of osmotic particles. Patients with nephrotic syndrome have both sodium retention and low intravascular oncotic pressure (as a result of low serum albumin). Thus fluid moves from the intravascular space to the extravascular space. Intravascular volume is depleted. Because these patients may also have prerenal azotemia (volume depletion), the fractional excretion of sodium is low and the urinary sodium concentration is low. However, the release of ADH also increases water reabsorption and the specific gravity of the urine is increased.

3.
(C)
Prednisone is the cornerstone of treatment in MCNS. If a patient becomes proteinuria free after 2-4 weeks of daily prednisone, the long-term prognosis is excellent. The 2 most serious complications of NS are infectious, especially with
Streptococcus pneumoniae
and gram-negatives because of defective opsonization of bacteria, and thromboembolic (TE) phenomena that occur secondary to loss of thrombinolytic proteins in urine. So immunization with a pneumococcal vaccine is indicated if a complete PCV-13 course had not been completed earlier. Some nephrologists might consider daily low-dose aspirin (ASA), but if used, ASA is usually reserved for patients with chronic nephrotic syndrome who fail to respond to prednisone and most likely have FSGS. Further anticoagulation is reserved for patients with clinical TE events. Similarly, although hyperlipidemia and its association with cardiovascular disease is a concern, HMG-CoA reductase inhibitors are not part of the initial treatment of nephrotic syndrome but are often considered in steroid nonresponders. Diphenhydramine can help the periorbital swelling caused by allergies. However, in this case, nephrotic syndrome (NS), and not allergy, caused the periorbital swelling.

4.
(B)
Patients with minimal change MCNS have 1 of 3 clinical courses. A third have 1 episode of NS syndrome, approximately a third have less than 4 relapses per year, and approximately a third have more than 4 episodes per year. All 3 groups have the same favorable outcome as long as they remain steroid responsive; they all “outgrow” the disease. However, frequently relapsing patients are at increased risk of adverse events while nephrotic and from exposure to steroids and other immunosuppressant agents.

S
UGGESTED
R
EADING

Brodehl J. The treatment of minimal change nephrotic syndrome: Lessons learned from multicentre cooperative studies.
Eur J Pediatr.
1991;150:380-387.

Fakhouri F, Bocquet N, Taupin P, et al. Steroid-sensitive nephrotic syndrome: from childhood to adulthood.
Am J Kidney Dis.
2003;41:550-557.

Koyama A, Fujisaki M, Kobayashi M, et al. A glomerular permeability factor produced human T cell hybridomas.
Kidney Int.
1991;40:453-460.

Sewell RF, Short CD. Minimal-change nephropathy: how does the immune system affect that glomerulus?
Nephrol Dial Transplant.
1993;8:108-112.

The primary nephrotic syndrome in children. Identification of patients with minimal change nephrotic syndrome from initial response to prednisone. A report of the International Study of Kidney Disease in Children.
J Pediatr.
1981;98:561-564.

CASE 126: A 12-YEAR-OLD GIRL WITH SMOKY-COLORED URINE

A 12-year-old girl had a sore throat. Two weeks later, she developed fever, smoky-colored urine, diffuse abdominal pain, and muscle pain. Her urine volume was about a cup for 24 hours.

On physical examination, the blood pressure was 210/130 mm Hg. There was mild facial edema, trace peripheral edema, and marked pallor. The lungs were clear to auscultation, and examination of the heart revealed normal sinus rhythm without any murmur. There was no rash.

The urinalysis revealed a grossly reddish smoky color, specific gravity 1.010, and protein 4+. The serum creatinine was 6.2 mg/dL, Na 135 mEq/L, K 6.5 mEq/L, C1 105 mEq/ L, and total HCO
₃
19 mmol/L. The antistreptolysin O antibody was more than 1000 IU/mL.

The C
₃
level was 30 mg/dL (normal: >90 mg/dL), and the ANA was negative.

SELECT THE ONE BEST ANSWER

1.
The differential diagnosis includes all except

(A) membranoproliferative glomerulonephritis (MPGN)

(B) acute poststreptococcal glomerulonephritis (APSGN)

(C) diffuse proliferative lupus nephritis (DPLN)

(D) subacute bacterial endocarditis (SBE) with immune complex glomerulonephritis

(E) immune globulin (Ig)A nephropathy

2.
Treatment at this time consists of all except

(A) volume reduction

(B) vasodilation

(C) penicillin

(D) dialysis