Diagnostic ultrasound ( PDFDrive )

CHAPTER 52 The Pediatric Urinary Tract and Adrenal Glands 1799
TABLE 52.8 Causes of Medullary
Nephrocalcinosis 86
Category
Hypercalciuria
Endocrine
Renal
Alimentary
Skeletal
Drugs
Miscellaneous
Urinary Stasis
Hyperoxaluria
Hyperuricosuria
Examples
Hyperparathyroidism
Cushing syndrome
Diabetes insipidus
Hyperthyroidism
Renal tubular acidosis
Milk alkali syndrome
Hypervitaminosis D
Immobilization
Metastatic disease
Furosemide
Steroids
Idiopathic hypercalciuria
Idiopathic hypercalcemia
Nephropathic cystinosis
Obstructive uropathy
Medullary sponge kidney
Primary
Secondary
A
perforating it and thereby providing a nidus for urinary stone
formation. 87 Sonography readily demonstrates calcium deposits
within the renal medullae (Fig. 52.37).
Urinary Stasis
Any form of urinary stasis predisposes not only to infection, but
to calcium deposition as well. hus the tubular ectasia encountered
in medullary sponge kidney and in autosomal recessive
polycystic kidney disease (ARPKD) oten shows deposits of
calcium in the pyramids, at the site of the dilated tubules. Similarly,
milk of calcium, a viscous colloidal suspension of various calcium
salts, may deposit in calyceal diverticula or in the renal pelvis
in the setting of UPJO 88 (Fig. 52.38). Staghorn calculi occasionally
occur in children with renal obstruction and infection (Fig. 52.39).
Renal Vein Thrombosis Calciications
he inely branching calciications within the cortex and medulla
of the kidney that develop ater renal vein thrombosis represent
microthrombi in the intrarenal veins 89 (Fig. 52.40).
Dystrophic Calciication
Dystrophic calciication of abnormal tissue can occur anywhere
in the urinary tract, including sites of inlammation resulting
from chronic infection or within a tumor or the wall of a cyst.
Urolithiasis
“Urolithiasis” refers to the presence of stones at any site within
the renal collecting system, ureter, bladder, or urethra. he
prevalence of urolithiasis varies according to age, sex, race, and
geographic region. 90 In the United States, urolithiasis occurs in
about 50 per 100,000 adolescents. 91 It is more common in
Caucasians than in African Americans. In adults, the highest
B
C
FIG. 52.37 (A) Renal medullary nephrocalcinosis in 13-year-old
boy with hypervitaminosis D. Longitudinal image of the left kidney
demonstrates echogenic calcium deposits completely illing the renal
pyramids (arrows). (B) Nephrocalcinosis in 18-year-old girl with Bartter
syndrome. Longitudinal image of the right kidney shows multiple
shadowing stones at the tips of the renal pyramids (arrows). (C) Longitudinal
color Doppler image of the right kidney reveals the twinkling
artifact associated with the stones.