Pediatric Examination and Board Review (220 page)

(E) no exceptions; all are correct

3.
Once the blood pressure is adequately controlled and renal function improves, outpatient management includes all except

(A) repeat C
₃
measurement in 6 weeks

(B) penicillin prophylaxis for dental work

(C) yearly urinalysis and blood pressure determination for 2-4 years

(D) minimize consumption of processed and fast foods

(E) all of the above

ANSWERS

1.
(E)
MPGN, APSGN, DPLN, and SBE are glomerulopathies associated with low C
₃
levels. In APSGN, C
₃
levels normalize without specific treatment within 6 weeks. In MPGN, DPLN, and SBE, C
₃
levels do not improve without treatment. In IgA nephropathy, C
₃
levels are normal.

2.
(D)
If one assumes that a patient with suspected APSGN was normotensive (119/76, 50th percentile 12-year-old girl) before the illness, then a blood pressure acutely rising to 210/130 represents a medical emergency. Blood pressure is determined by cardiac output and vascular resistance. In APSGN, glomerular filtration is reduced and patients are hypervolemic. Rational treatment is volume reduction with diuretics and fluid restriction, but this patient also needs urgent reduction in blood pressure. There is a considerable lag period between volume reduction and a decrease in the blood pressure. Therefore vasodilation is also acutely necessary. If a patient has evidence of active streptococcal infection or has not been treated, penicillin is indicated to decrease the spread of a nephritogenic strain of streptococcus. Close contacts should be evaluated for streptococcal infections as well. Penicillin treatment, however, will not alter the natural history of APSGN once it has developed. Dialysis at this point is not indicated. Most minor electrolyte imbalances can be managed conservatively. Should this patient have intractable hypervolemia with pulmonary edema, hyperkalemia, acidosis, uremia, or uncontrollable hypertension, acute dialysis is indicated.

3.
(B)
It is important to document that the C
₃
level returns to normal. This confirms the diagnosis of APSGN and rules out MPGN, DPLN, and SBE. Because only a few strains of group A betahemolytic streptococci are nephritogenic and the patient now presumably has immunity to at least one of these strains, penicillin is not continued as prophylaxis after initial treatment. In children, most cases of APSGN have an excellent prognosis. However, long-term follow-up has revealed an increased incidence of hypertension and other renal sequelae, especially if the initial presentation was associated with severe renal failure. Therefore yearly urinalysis and blood pressure determination should be performed. Avoidance of processed foods and fast foods that contain preservatives is indicated for all children, including those who have had APSGN.

S
UGGESTED
R
EADING

Lewy JE, Salinas-Madrigal L, Herdson PB, et al. Clinicopathologic correlations in acute poststreptococcal glomerulonephritis: a correlation between renal functions, morphologic damage, and clinical course of 46 children with acute poststreptococcal glomerulonephritis.
Medicine
(
Baltimore
). 1971;50:453-501.

Potter EV, Lipschultz SA, Abidh S, et al. Twelve to seventeenyear follow-up of patients with poststreptococcal acute glomerulonephritis in Trinidad.
N Engl J Med.
1982;307:725-729.

Tejani A, Ingulli E. Poststreptococcal glomerulonephritis. Current clinical and pathologic concepts.
Nephron.
1990; 55:1-5.

CASE 127: A 5-YEAR-OLD BOY WITH BLOODY DIARRHEA AND OLIGURIA

A 5-year-old boy from Houston is vacationing with his parents and 2 siblings in Colorado. They have visited a water slide park. Two days later, the patient developed diarrhea, which turned bloody. The bloody diarrhea was associated with crampy abdominal pain and vomiting. When the vomiting started, the patient was taken to a local emergency department where he was given intravenous (IV) fluids and prescribed loperamide for diarrhea. One day later, the patient returned to the emergency department because he looked pale, became somnolent, and had not urinated for 24 hours.

On physical examination this lethargic and paleappearing 5-year-old had a temperature of 100.4°F (38°C), a pulse of 100 beats/minute, a respiratory rate of 24/minute, and a blood pressure of 128/85 mm Hg. The chest was clear to auscultation and there was mild pretibial edema. The abdominal examination was remarkable for moderate diffuse tenderness without rebound; the liver measured 3 cm below the right costal margin.

The initial laboratory investigations revealed a hemoglobin (Hgb) of 8 g/dL, leukocyte count 17,500 μL, and a platelet count of 21,000/μL; the peripheral blood smear showed 12% schistocytes. The BUN was 35 mg/dL, and the serum creatinine was 2.5 mg/dL. The serum Na was 141 mEq/L, K 5.6 mEq/L, Cl 105 mEq/L, and total HCO
₃
18 mmol/L. The serum calcium was 8.2 mg/dL, inorganic phosphorus 7.0 mg/dL, and glucose 310 mg/dL. C3 is normal.

During the next 24 hours, the patient’s urinary output decreased to 55 mL/24 hours, with an increase in the serum creatinine to 3.8 mg/dL. Because the patient remained severely oliguric and uremic with symptoms of nausea and vomiting, peritoneal dialysis was started. After 3 weeks of peritoneal dialysis, the urine output rose to 200 mL/24 hours and platelet count increased to 95,000/μL.

SELECT THE ONE BEST ANSWER

1.
The prognosis for recovery of renal function is generally favorable. Mortality during the acute illness is less than 5% but increases in the presence of risk factors. This patient’s major risk factor was

(A) leukocytosis

(B) pancreatic involvement with glucose intolerance

(C) schistocytes on his blood smear

(D) initial platelet count 21,000/μL

(E) B and D

2.
Although found in other animals, the main vector of
E coli
O157: H7 is

(A) chicken

(B) dogs

(C) pigs

(D) cattle

(E) humans

3.
Early treatment of diarrhea with antibiotics in this case

(A) decreases the likelihood that siblings will develop
E coli
O157:H7 diarrhea

(B) decreases the likelihood that the patient will develop hemolytic-uremic syndrome (HUS)

(C) increases the likelihood that the patient will develop HUS

(D) exacerbates diarrhea

(E) A and B

4.
In the present case, which treatment has been shown to be most efficacious?

(A) supportive treatment

(B) plasma infusion and/or plasma exchange

(C) IV immune globulin

(D) tissue-type plasminogen activator

(E) oral shiga toxin–binding agent

ANSWERS

1.
(A)
Those children who do not do well during the acute episode of diarrheal-associated hemolytic uremic syndrome (d+HUS) often have one or more risk factors. Risk factors for death in the initial phase are oligoanuria, dehydration, WBC more than 20,000/ mm
³
, and hematocrit more than 23%. Risk factors for long-term complications of HUS are initial anuria lasting longer than 5 days, oliguria longer than 10 days, WBC more than 20,000/mm
³
, or histology on biopsy showing microangiopathy of more than 50% of glomeruli, arterial microangiopathy, and/or cortical necrosis. An increased leukocyte count at presentation reflects neutrophil activation resulting from toxin-induced release from monocytes of the neutrophil chemoattractant interleukin 8; these neutrophils may then contribute to tissue damage. Older age at onset of the disease is a risk factor; up to 70% of children 3 years of age or older progress to terminal renal failure. Schistocytes are part of the diagnosis of hemolysis in the syndrome as is uremia. Atypical HUS occurs at all ages, without gastrointestinal symptoms, and often with an insidious onset. A high proportion of these patients have permanent renal sequelae and recurrence after transplant.

2.
(D)
Although found in other animals, cattle are the main vector of
E coli
O157:H7, with the bacteria present in the intestine and feces. Infection in humans occurs following ingestion of contaminated, undercooked meat, nonpasteurized milk or milk products, water, fruits, and vegetables.

3.
(C)
Early administration of antibiotics to children with diarrhea caused by
E coli
O157:H7 may promote the development of HUS, perhaps by enhancing release of shiga toxin as the bacteria are killed. A prospective study of 71 children younger than 10 years with
E coli
O157:H7 isolated from stool found that those receiving antibiotics were more likely to develop HUS (5 of 9 [56%] versus 5 of 62 who were untreated [8%],
p
= 0.002).

4.
(A)
Four modalities have been tried in the treatment of HUS: plasma infusion and plasma exchange; antithrombotic agents, oral shiga toxin–binding agents, and tissue-type plasminogen activator. Antithrombotic agents based on the histologic evidence of thrombus formation have not been shown to influence duration of renal failure, hemolysis, thrombocytopenia, or long-term outcome. Furthermore, hemorrhagic complications are more common in treated patients. The use of plasma infusion (to supply a missing anticoagulant factor) or plasma exchange with plasma replacement (to also remove procoagulant factors) has been successful in many adults with thrombotic thrombocytopenic purpura (TTP)/HUS, but in children with typical HUS, plasma infusion has not been shown to be beneficial in the long term. A toxin-binding oral agent did not improve clinical outcome in 145 children with HUS. Early research shows restoring or providing tissue-type plasminogen activator (ie, alteplase) may improve renal function. It is difficult to evaluate the efficacy of such treatment in a disease with such a good long-term prognosis (ie, 90% with normal glomerular filtration rate [GFR]). Finally, IV immunoglobulin, possibly by neutralizing antibodies against shiga-like toxins, has not been shown to influence the duration of hemolysis, thrombocytopenia, or acute renal failure.