A7-year-old boy was brought to his pediatrician because he had developed hematuria, which required
hospitalization. Approximately 6 weeks before his admission, he had a severe sore throat but received no
treatment for it. Subsequently, he did well except for complaints of mild lethargy and decreased appetite.
Approximately 3 weeks before admission, he had a temperature of 101° F daily for 7 days. He complained of
minimal bilateral back pain. Physical examination revealed a well-developed young boy with moderate bilateral
costovertebral angle (CVA) tenderness. The remainder of the physical examination results were negative. His
blood pressure was 140/100 mm Hg in both arms and legs.
Studies
Results
Urinalysis, p. 956
Blood
+4 (normal: negative)
Protein
+1 (normal: negative)
Red blood cell casts
Positive (normal: negative)
Specific gravity
1.025 (normal: 1.010-1.025)
Color
Red-tinged (normal: amber-yellow)
Urine culture and sensitivity (C&S), p. 973
No growth after 48 hours
Blood urea nitrogen (BUN), p. 511
42 mg/dL (normal: 7-20 mg/dL)
Creatinine, p. 190
1.8 mg/dL (normal: 0.7-1.5 mg/dL)
Creatinine clearance test, p. 193
64 mL/min (normal: approximately 120 mL/min)
Renal ultrasound, p. 866
No tumor; kidneys diffusely enlarged and edematous
Intravenous pyelogram (IVP), p. 1057
Delayed visualization bilaterally; enlarged kidneys, no tumor; no obstruction seen
Renal biopsy, p. 754
Swelling of glomerular tuft, along with polymorphonuclear leukocyte infiltrates in Bowman's capsule (findings
compatible with glomerulonephritis); immunofiuorescent staining, positive for IgG
Anti-DNase-B (ADB) titer, p. 79
200 units (normal: $170 units)
Total complement assay, p. 172
33 units/mL (normal: 75-160 units/mL)
Case Studies 2
Diagnostic Analysis
The blood, protein, and RBC casts in the boy's urine indicated a primary renal disorder. The elevated creatinine
and BUN levels indicated that the problem was severe and markedly affecting his renal function. Both kidneys
were probably equally impaired. Intravenous pyelogram (IVP) was helpful only in ruling out Wilms tumor or
congenital abnormality. Normally an IVP would not be performed in light of this patient's impaired renal function.
It is presented here for demonstration of the information it can provide. Renal ultrasound is a much safer test to
visualize the kidney to exclude neoplasm. The ultrasound findings were compatible with an inflammatory
process involving both kidneys. Renal biopsy was most helpful in suggesting glomerulonephritis. The history of
recent pharyngitis, fever, the positive ASO titer, the positive ADB titer, and the finding of immunoglobulin IgG
antibodies on the immunofluorescent stain all suggested poststreptococcal glomerulonephritis.
The patient was placed on a 10-day course of penicillin. He was given antihypertensive medication, and his fluid
and electrolyte balance was closely monitored. At no time did his creatinine or BUN level rise to a point requiring
dialysis. After 6 weeks, his renal function returned to normal (creatinine, 0.7 mg/dL; BUN, 7 mg/dL). His
antihypertensive medications were discontinued, and he remained normotensive and returned to normal activity.
Critical Thinking Questions
- At what point would the BUN and creatinine have signified the need for dialysis?
- What was the cause of the patient's hypertension?
Sample Solution