Raymond D. Adelman

Renal calcification in preterm infants: Pathophysiology and long-term sequelae

We examined the clinical course of 17 preterm infants with chronic lung disease who received loop diuretics and developed nephrocalcinosis; nine of them were followed for up to 4.5 years. The mean gestational age was 26.8 weeks (SD 2.2 weeks), and mean birth weight was 830 gm (SD 276 gm). The diagnosis of renal calcification was made at a mean age of 12 weeks (SD 6.5 weeks) by abdominal x-ray examination, screening abdominal ultrasound studies or, both. Calcification was associated with both furosemide therapy and the presence of multiple potential risk factors. Renal calcification, length, and function were subsequently evaluated in nine patients at a mean age of 21.3 months (SD 15.3 months). Improvement in calcification occurred in five patients, with total resolution in four. Renal length, determined by ultrasound examination and corrected for body length, was normal in 17 of 18 kidneys. Serum creatinine values and calculated glomerular filtration rates were abnormal in four of nine patients. We conclude that renal calcification in preterm infants is associated with multiple risk factors, including furosemide usage, and tends to diminish during the first year of life. However, renal function may remain compromised in some patients.

Gentamicin nephrotoxicity in the dog: sequential light and electron microscopy.

Sequential percutaneous renal biopsies in six dogs given gentamicin at 10 mg/kg every 8 hours (intramuscular) were examined before treatment and 5, 9 and 12 days after treatment. Renal function tests (blood urea nitrogen and serum creatinine) and urinary enzyme excretion (β glucuronidase, N acetyl-glucosaminidase, galactosidase and muramidase) were measured daily. Periodic acid Schiff (PAS)-stained, 3-μm sections of renal biopsies taken before drug treatment showed pale and swollen proximal tubular epithelium that occluded the tubular lumen. The apical surface of all proximal tubules (brush border) stained intensely. On day 5, brush border staining was decreased or absent and many proximal tubules had open lumina and hyaline globules in the cytoplasm. Ultrastructurally, the numbers of cytoplasmic lysosomes were increased and most contained large lamellar inclusions (myelin figures). Biopsies on day 9 were characterized by an increase in the size and number of cytoplasmic hyaline globules and an absence of brush border staining. Scattered proximal tubule cells were necrotic. Intact proximal tubules and other parts of the nephron frequently contained amorphous granular casts or necrotic debris. Ultrastructurally, proximal tubules had intact brush borders and showed a remarkable increase in the number and size of lysosomes of all types. On day 12 the severity of these changes progressed, and cytosegrosomes became numerous. Urinary enzyme levels (β glucuronidase and N acetyl-glucosaminidase) were elevated by day 2, galactosidase elevated by day 4 and muramidase elevated by day 5. Clinically significant elevations in serum creatinine (day 6) and blood urea nitrogen (day 12) were preceded by elevations in urinary enzyme excretion and by severe alterations in renal tubular morphology.

Long-term follow-up of neonatal renovascular hypertension

Twelve neonates with hypertension have been followed for a mean of 5.75 years. At onset of hypertension, mean peak blood pressure was 159/99 mmHg. Ten infants had umbilical artery catheters, 9 placed above the origin of the renal arteries. Radionuclide renal scan, and/or angiography demonstrated renovascular disease, primarily renal artery thrombosis, in 11 infants. Onethird of infants were asymptomatic, one-third had normal urinalyses and two-thirds had elevated peripheral plasma renin activities. Blood pressure normalized with medical therapy in all infants and remained normal when therapy was discontinued. Ten infants have normal creatinine clearances on follow-up but 5/11 have unilateral renal atrophy. Radionuclide scans have remained abnormal, even in infants without renal atrophy. In summary, neonatal renovascular hypertension is frequently secondary to renal artery thrombosis, associated with umbilical artery catheterization. Blood pressure usually normalizes with conservative medical management and remains normal off medications. Persistent abnormalities in renal size and function are common.

Renovascular Hypertension as a Complication of Umbilical Arterial Catheterization

Renovascular hypertension (RVH) in the neonatal period is frequently associated with thromboembolic complications of umbilical artery catheterization. Seven newborn infants with RVH were studied by angiography and/or radionuclide examination. Aortography and, in one case, selective angiography showed variable degrees of renal artery occlusion or attenuation. Thromboembolic defects were frequently present in other vessels. Radionuclide flow studies, renograms, and computer analysis of data (ADAC) demonstrated defects in renal function, indicative of renal ischemia. There was a high degree of correlation between angiographic and radionuclide studies. Successful medical management suggests a more conservative alternative to nephrectomy in the hypertensive newborn.

BILATERAL RENAL HYPOPLASIA WITH OLIGOMEGANEPHRONIA

Abstract A patient with clinical, laboratory, and biopsy findings of bilateral renal hypoplasia with oligomeganephronia is presented, and the differential diagnosis of small kidneys in children is discussed.

Urinary symptoms in child sexual abuse.

Many common genitourinary complaints may be related to sexual abuse. We report five patients referred to a Pediatric Nephrology Clinic who demonstrate some of the symptoms and signs caused by abuse, such as dysuria, genital and urinary tract infections, voiding dysfunction, and genital trauma. Difficulties in eliciting histories are described. Although these genitourinary complaints may be due to a variety of etiologies, sexual abuse should not be overlooked. Suggestions for a management approach are made.

A controlled study of the nephrotoxicity of mezlocillin and gentamicin plus ampicillin in the neonate

The nephrotoxicity of the aminoglycoside gentamicin was evaluated in an open, controlled study of newborn infants randomly allocated to receive either combination drug therapy with gentamicin and ampicillin or single drug therapy with mezlocillin for treatment of presumed neonatal sepsis. There were no significant differences in initial clinical characteristics between the groups. Neonates receiving gentamicin, in contrast to those receiving mezlocillin, had significant nephrotoxicity manifested by a smaller postnatal fall in mean serum creatinine concentration (-9%, P NS vs -21%, P less than 0.005, respectively) and a diminished postnatal rise in mean creatinine clearance (+ 21%, P NS vs + 51%, P less than 0.01, respectively). In neonates with a fall in creatinine clearance, the mean decline was significantly greater in those receiving gentamicin (44% vs 20%, P less than 0.01). There was no relationship between the incidence of gentamicin nephrotoxicity and either peak or trough gentamicin levels. For treatment of presumed neonatal sepsis, gentamicin proved more nephrotoxic than mezlocillin.

Systolic blood pressure and heart rate in the growing beagle puppy

Systolic blood pressure and heart rate were measured in beagle puppies from 1 week to 6 months of age. A significant increase in blood pressure and decrease in heart rate occurred with growth. These changes are qualitatively similar to those observed in young infants and children. The beagle puppy may be a useful animal model for the study of normal and abnormal maturational changes in blood pressure and heart rate and for the evaluation of pharmacologic agents currently used in the treatment of cardiovascular disease in the growing and developing infant.

Abdominal aortic aneurysm 18 years after apparent resolution of an umbilical catheter-associated aortic thrombosis

A young man was found to have an abdominal aortic aneurysm 18 years after the apparent resolution of an umbilical artery catheter-associated aortic thrombosis. This report underlines the need for long-term follow-up studies of infants with catheter-related vascular thrombosis.

Hypertension in the neonate following closure of abdominal wall defects

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