Neonatal Renal System1

8/2/2019 Neonatal Renal System1

1/64


2/64

Hanan Fathy

Pediatric Nephrology Unit

2011


3/64

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


4/64


5/64


6/64

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.


7/64

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.


8/64


9/64


10/64

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


11/64

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


12/64


13/64


14/64

EPIDEMIOLOGY:

Renal disorders are a heterogeneous group ofcongenital and acquired conditions.

Anomalies are detected in ~1% of fetuses byprenatal ultrasound, in


15/64

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).


16/64

Oligohydramnios

Renal agenesis (Potters Syndrome)

Hypoplasia

Dysplasia

Severe urinary tract obstruction


17/64

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


18/64

CLINICAL MANIFESTATIONS

Potters syndrome

Dysmorphic features

Lateral abdominal massAscitesSuprapubic mass

Abdominal wall defectsFailure to palpate kidney

HypertensionAnuria or oliguria


19/64


20/64

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


21/64

CONGENITAL RENAL DISORDERS

Renal Agenesis

Renal Hypoplasia

Renal Dysplasia Oligomeganephroma


22/64

Ectopic Kidney(simple renal ectopia)


23/64

Ectopic Kidney Locations


24/64

Horseshoe Kidney


25/64

P l ti Kid Di


26/64

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


27/64

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


28/64

Genitourinary Problems

Obstructive uropathies (PUV,UPJ,UVJ)

Vesicourethral reflux

Bladder exstrophy

Cloacal exstrophy

Prune Belly Syndrome

Ambiguous genitalia

Hypo/Epispadias


29/64

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


30/64

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


31/64

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.


32/64


33/64


34/64


35/64


36/64


37/64

Bladder Exstrophy


38/64


39/64


40/64

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


41/64


42/64

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


43/64

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


44/64

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.


45/64

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.


46/64

INCIDENCE

More common in patients with certain

diagnoses :

BPD 6 %

PDA 3 %

IV hemorrhage 3 %

Umbilical catheterization 9 %


47/64

Causes of Hypertension

Leigh M. Ettinger and Joseph T. Flynn. Hypertension inthe Neonate. NeoReviews 2002;3;151.


48/64

EVALUATION

Life-threatening presentation

CHF

Cardiogenic shock

Seizures

Presentation of less ill infants

feeding difficulties

unexplained tachypnea

lethargy, apnea, irritability

mottling of the skin


49/64

EVALUATION

RED FLAGS IN THE HISTORY

prenatal exposures to heroin and

cocaine

predisposing conditionsBPD, CNS

disorders, PDA, hypervolemia (post

BT)

Medications/ Umbilical artery

catheterizations


50/64

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


51/64

EVALUATION

RED FLAGS IN THE PHYSICAL

EXAMINATION

Abdominal distentionobstructive

uropathy, PKD, tumors

Peripheral thrombiUAC related HTN

Tachycardia/flushing/LBW

hyperthyroidism

Ambiguous genitalia - CAH


52/64

LABORATORY EXAMINATIONS

Urinalysis

CBC

Electrolytes, BUN, S.cr, Ca

Urine culture if UTI is suspected

Plasma renin levelsignificantly

elevated level indicates renovasculardisease


53/64

LABORATORY EXAMINATIONS

Additional tests

Thyroid studies

VMA/Homovanillic acid

Aldosterone

Cortisol


54/64

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


55/64

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


56/64

MANAGEMENTRECOMMENDATION

Asymptomatic /Mild Hypertension

(Systolic 95th to < 99th %) observation

resolves in time

Moderate to Severe

(Systolic >/= 99th %) antihypertensive therapy


57/64

MANAGEMENT

Address correctible causes of

hypertension

treat pain

correct volume overload

wean inotropic infusion

Choose a suitable agent

depends on specific clinical situation


58/64

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


59/64

TREATMENT

ACUTELY ILL INFANTS

continuous IV infusion Nicardipine

Nitroprusside Labetalol cathecholamine and CNS

mediated hypertension

- avoid in BPD

monitor BP Q 10-15 minutes


60/64

TREATMENT

LESS SEVERE HYPERTENSION NOTREADY FOR ORAL

Intermittent IV agents

Hydralazine

Labetalol

Sometimes doses at lower end of

recommended range cause significanthypotension

TREATMENT


61/64

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)


62/64

TREATMENT

Surgical correction

CoA

UPJ obstruction

Medical management + surgery

Renal artery stenosis

Nephrectomy

Cystic kidney disease Chemotherapy + surgery

Wilms tumor and Neuroblastoma


63/64

Leigh M. Ettinger and Joseph T. Flynn. Hypertensionin the Neonate. NeoReviews 2002;3;151.


64/64

Neonatal Renal System1

Documents

Transcript of Neonatal Renal System1