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Hanan Fathy
Pediatric Nephrology Unit
2011
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Three sets of kidneys form in mammalian embryos: the
pronephros,mesonephros , and metanephros.
The formation of the pronephros occurs a 2 to 3 weeks ofgestation, followed by the mesonephros, which appears at 4 to5 weeks of gestation. However, the first glomeruli do notdevelop until 9 weeks gestation.
Nephrogenesis is complete by 34 to 36 weeks gestation,resulting in 0.7 to 1 million nephrons per kidney. Maturation ofthe nephrons begins in the juxtaglomerular region,extending
out ward toward the renal cortex
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Urine production begins at 10 to 12 weeksgestation.
A total of 5mL/hour of urine is produced by 20weeks gestation, which comprises 90% of theamniotic fluid volume by this gestational age,reaching 50mL/hour by 40 weeks of gestation.
Fetal hemodynamics and urine formation are
affected by maternal factors such as the maternalvolume status, drugs, and vasoactive substances thatcross the placenta.
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Compared to the adult, the GFR of a term new
born baby is less than 10% of the adult level and
correlates closely with the gestational age.
However, during the first 2 weeks of life, the GFR
doubles and continues to increase, reaching adult
levels by 2 years of age.
This increase lags in premature babies.
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Physiological Differences of the Fetus and Newborn kidney
versus Adults
1. Premature neonates show decreased renal blood flow comparedto term newborn.
2. Concentrating and diluting ability is compromised.
3. Acid base regulation is limited.
4. Sodium reabsorption and excretion is limited.
5. Natriuretic response to sodium is limited.
6. Ability to excrete hydrogen ions is limited
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The decreased neonatal kidney concentrating
ability is due to:
Short Henles loop
Tubule insensitivity to ADH Decreased GFR
Decreased urea excretion
Newborns cannot concentrate urine, hencepolyuria
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EPIDEMIOLOGY:
Renal disorders are a heterogeneous group ofcongenital and acquired conditions.
Anomalies are detected in ~1% of fetuses byprenatal ultrasound, in
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PRENATAL DIAGNOSIS OF RENAL DISEASE
Usually by fetal ultrasonograms that detect signsof obstructive uropathy.
Fetal hydrops may occur with congenitalnephrotic syndrome.
Oligohydramnios occurs with severe urinary tractobstruction or renal agenesis, which is associatedwith pulmonary hypoplasia (Potters syndrome).
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Oligohydramnios
Renal agenesis (Potters Syndrome)
Hypoplasia
Dysplasia
Severe urinary tract obstruction
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Polyhydramnios Nephrogenic diabetes
insipidus Bartters Syndrome
Hypertrophied placenta
Placenta is >25% of the NBweight
Associated with Finnish-type nephrotic syndrome
Always evaluate the
placental vessels (2aa, 1v)
Umbilical cord anomalies
Renal hypoplasia Hydronephrosis
Double renal pelvis
Ureteral stricture
Bladder extrophy
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CLINICAL MANIFESTATIONS
Potters syndrome
Dysmorphic features
Lateral abdominal massAscitesSuprapubic mass
Abdominal wall defectsFailure to palpate kidney
HypertensionAnuria or oliguria
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Possible Physical findings
High imperforate anus
Abnormal external genitalia
Supernumerary nipplesPreauricular pits and ear tags
Cervical cysts or fistula
Hearing loss
Aniridia
Coloboma
Optic disc dysplasia
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CONGENITAL RENAL DISORDERS
Renal Agenesis
Renal Hypoplasia
Renal Dysplasia Oligomeganephroma
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Ectopic Kidney(simple renal ectopia)
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Ectopic Kidney Locations
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Horseshoe Kidney
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P l ti Kid Di
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Polycystic Kidney DiseaseAutosomal Recessive
Infantile PKD
Autosomal Dominant
Adult PKD
Frequency 1/40,000 1/10,000
Chromosome 6p21 16 (Codes for polycystin)
Diagnosis Fetal U/S: large echogenic
kidneys, oligohydramnios
Rarely findings at birth
Cysts Kidneys liver, as older
Large>2cms
Kidney, liver, pancreas,
spleen. Variable size
Problems Severe HTN, hepatic
fibrosis, biliary dysgenesis,
Potters Sequence
HTN, renal insufficiency.
Worse as older
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Multicystic dysplastic kidney vs. Polycystic kidney
disease
MCDK
More common - 1/4000
Unilateral
SporadicUnilateral mass
Check urinary tract (90% w/ otherGU anomalies)
PKD
AD - 1/10000, AR - 1/40000
Bilateral
GeneticHTN/ renal insufficiency/
oliguria/ Family hx
Check liver, spleen, pancreas
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Genitourinary Problems
Obstructive uropathies (PUV,UPJ,UVJ)
Vesicourethral reflux
Bladder exstrophy
Cloacal exstrophy
Prune Belly Syndrome
Ambiguous genitalia
Hypo/Epispadias
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Frequency
Genitourinary system hashighest percentage ofanomalies (genetic,congenital) of all organsystems
Incidence 10%
May represent up to 50% ofall abnormalities found inutero via ultrasound
I ti ti d t f t t ll
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Investigation and management of antenatally
detected hydronephrosis Antenatal hydronephrosis (ANH) affects approximately 1% of
pregnancies.
Anterior Posterior Diameter (APD) is the most common method forreporting antenatal ANH.
Children with ANH have been shown to have a significantly higherrisk of developing a urinary tract infection (UTI) than controls.Therefore, some recommend institution of prophylactic antibiotics atbirth
Commonly used prophylaxes in the neonate include amoxicillin 50mg per day and cephalexin 50 mg per day.Trimethoprim-sulfamatholxazole and nitrofurantoin should NOT be used in the
neonate
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Investigation and management of antenatally
detected hydronephrosis
1. All ANH should be investigated with a postnatal renal US.
2. The role of prophylactic antibiotics initiated at birth is controversial.
3. The need to further investigate mild postnatal hydronephrosis with a VCUGis controversial, and depends on the physicians attitude toward diagnosingasymptomatic VUR.
4. The need to reassess mild postnatal hydronephrosis with a second RUS isunclear, but does provide reassurance to the physician and parent if the ANH
remains stable or improves.
5. Persistent moderate or severe hydronephrosis should be investigated with aVCUG, followed by diuretic renography if the hydronephrosis cannot beexplained by VUR.
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Bladder Exstrophy
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Vascular disorders
Acute tubular necrosis (vasomotornephropathy)
Corticomedullary necrosis
Renal venous thrombosis
Microemboli
Adrenal hemorrhage
Cystic diseases
Infantile polycystic disease Adult polycystic disease
Cystic dysplasia
Multicystic kidney
Hydronephrosis
Obstruction Severe ureteral reflux
Interstitial nephritis
Infection
Sepsis
UTI
Drugs
Penicillin
Aminoglycosides
Anticonvulsant
Diuretics
Tumors Wilms Tumor
Mesoblastic nephroma
Fetal hamartomas
Angiomas
Glomerulonephritis
Infection-mediated
Immunologically-mediated
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Neonatal Hypertension
Healthy newborns 0.2%
Babies after NICU care 2.6%
Infants with CLD up to 40%
Worry about end organ damage Cardiac Heart failure
Retinal Retinopathy
CNS Encephalopathy
Renal
Watkinson et al. Hypertension in the newborn baby.Arch Dis Child Fetal Neonatal. 86:F78-81, 2002
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DEFINITION
Systolic and/or diastolic BP >/= 95%
(> 2 SD above the mean)
Stage 1 : BP at 95 to < 99 %
Stage 2 : BP >/= 99% + 5 mm Hg
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Getting the correct BP
First reading frequently higher than third
Nwanko et. al. recommends following
protocol: check BP 1.5 hours after the last feeding or intervention
Apply appropriately sized cuff
2/3 the length of the limb segment
Defined size markers on cuffs
Wait 15 minutes/until patient still
obtaining three successive readings at 2-minute
intervals.
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BLOOD PRESSURE
MEASUREMENT
Intra-arterial catheters
most accurate technique
placed in aorta or radial artery
continuous readings
Oscillometric devices
non-invasive ; continuous
measure systolic and mean and calculatediastolic pressure.
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INCIDENCE
More common in patients with certain
diagnoses :
BPD 6 %
PDA 3 %
IV hemorrhage 3 %
Umbilical catheterization 9 %
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Causes of Hypertension
Leigh M. Ettinger and Joseph T. Flynn. Hypertension inthe Neonate. NeoReviews 2002;3;151.
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EVALUATION
Life-threatening presentation
CHF
Cardiogenic shock
Seizures
Presentation of less ill infants
feeding difficulties
unexplained tachypnea
lethargy, apnea, irritability
mottling of the skin
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EVALUATION
RED FLAGS IN THE HISTORY
prenatal exposures to heroin and
cocaine
predisposing conditionsBPD, CNS
disorders, PDA, hypervolemia (post
BT)
Medications/ Umbilical artery
catheterizations
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EVALUATION
RED FLAGS IN THE PHYSICAL
EXAMINATION
BP in lower extremities/non-palpablefemoral pulsesCoA
dysmorphic featuresCAH/Turner Sy
Flank massUPJ obstruction Epigastric bruitrenal artery stenosis
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EVALUATION
RED FLAGS IN THE PHYSICAL
EXAMINATION
Abdominal distentionobstructive
uropathy, PKD, tumors
Peripheral thrombiUAC related HTN
Tachycardia/flushing/LBW
hyperthyroidism
Ambiguous genitalia - CAH
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LABORATORY EXAMINATIONS
Urinalysis
CBC
Electrolytes, BUN, S.cr, Ca
Urine culture if UTI is suspected
Plasma renin levelsignificantly
elevated level indicates renovasculardisease
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LABORATORY EXAMINATIONS
Additional tests
Thyroid studies
VMA/Homovanillic acid
Aldosterone
Cortisol
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IMAGING STUDIES
CXRay/2D echoCHF
US of genitourinary tract
should be performed in all hypertensive infants
to rule out UPJ obstruction, renal vein
thrombosis
Doppler flow studies
Abdominal/pelvic US
VCUG
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IMAGING STUDIES
Radionuclide imaging - Abnormal kidney displays:
decreased effective renal plasma flow
decreased urine flow rate
increased isotope concentration
MRAgold standard for diagnosis of
reno vascular hypertension
must be 3 kg
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MANAGEMENTRECOMMENDATION
Asymptomatic /Mild Hypertension
(Systolic 95th to < 99th %) observation
resolves in time
Moderate to Severe
(Systolic >/= 99th %) antihypertensive therapy
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MANAGEMENT
Address correctible causes of
hypertension
treat pain
correct volume overload
wean inotropic infusion
Choose a suitable agent
depends on specific clinical situation
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TREATMENT
ACUTELY ILL INFANTS
continuous IV infusion
intermittently administered agents cause
wide fluctuation in BP
Patients are at increased risk for cerebral
ischemia and hemorrhage from rapidly
falling BPs.
Titrate for desired effect
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TREATMENT
ACUTELY ILL INFANTS
continuous IV infusion Nicardipine
Nitroprusside Labetalol cathecholamine and CNS
mediated hypertension
- avoid in BPD
monitor BP Q 10-15 minutes
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TREATMENT
LESS SEVERE HYPERTENSION NOTREADY FOR ORAL
Intermittent IV agents
Hydralazine
Labetalol
Sometimes doses at lower end of
recommended range cause significanthypotension
TREATMENT
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TREATMENT
INFANT READY TO BE WEANED FROM IV
/ READY FOR ORAL
ORAL ANTIHYPERTENSIVE AGENTS
Captopril
Diuretic - can be added if captopril is
ineffective
B Blockershould be avoided (BPD)
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TREATMENT
Surgical correction
CoA
UPJ obstruction
Medical management + surgery
Renal artery stenosis
Nephrectomy
Cystic kidney disease Chemotherapy + surgery
Wilms tumor and Neuroblastoma
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Leigh M. Ettinger and Joseph T. Flynn. Hypertensionin the Neonate. NeoReviews 2002;3;151.
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