VLC Peds 1: Infant (0-6mo) Flashcards
Where does bilirubin come from?
RBC breakdown → Hb release → converted to unconjugated bilirubin → binds to albumin in blood stream (not soluble in water)
How is bilirubin processed?
Albumin-bound unconjugated bilirubin → Liver: bilirubin extracted by hepatocytes → conjugated (with gluconuride, by UDPGT): now it’s water soluble!
→ bile → intestines
How is bilirubin excreted in adults?
conjugated bilirubin in bile in intestines → urobilin → excreted in stool
What is different about bilirubin excretion in neonates?
Same process up till intestines, but: Babies: ø GI flora
Bilirubin is de-conjugated (by an enzyme in meconium), reabsorbed into the bloodstream.
What is the most serious problem that can result when a newborn infant has high levels of unconjugated bilirubin?
Kernicterus, neurologic impairment, brain damage, or encephalopathy
What is kernicterus (etiology/pathology)?
staining of the basal ganglia and cranial nerve nuclei by bilirubin, due to high levels of unconjugated bilirubin
What is kernicterus (clinically)?
Chronic clinical condition due to high levels of unconjugated bilirubin. Results in:
- abnormalities in tone and reflexes
- choreoathetosis
- tremor
- oculomotor paralysis
- sensorineural hearing loss
- cognitive impairment
When does acute bilirubin encephalopathy occur?
First few weeks of life
What are the initial signs of acute bilirubin encephalopathy?
Initial signs include: poor suck high-pitched cry hypotonia lethargy seizures
What are are late signs of acute bilirubin encephalopathy?
extensor hypertonia, opisthotonus
What is opisthotonus?
abnormal posturing: rigidity and severe arching of the back, with the head thrown backward
(From Greek “drawn backwards”)
What has made kernicterus less common?
- Prevention: Rh screening and RhoGAM (preventing erythroblastosis fetalis)
- Treatment of hyberbilirubinemia with phtootherapy
What is erythroblastosis fetalis / neonatorum?
hemolytic anemia in the fetus/neonate due to maternal Ab to fetal RBC. (Ab transmitted via placenta).
Usually d/t incompatible blood groups, often Rho(D) antigens
What are the major etiologies of early newborn jaundice
- Physiologic Jaundice
- Jaundice associated with breastfeeding
- Hemolysis
- Non-hemolytic red cell breakdown
- Metabolic errors
- Neonatal sepsis
- Congenital infection
When is physiologic jaundice first noticed in a full-term baby, and when does the bilirubin level peak?
First noticed day 2-3, bilirubin peak day 3-4
What is physiologic jaundice?
This is defined as a total bilirubin level [elevated – check values ≤ 15 mg/dL (≤ 257 μmol/L)] in full-term infants who are otherwise healthy and have no other demonstrable cause for elevated bilirubin.
What factors promote enterohepatic circulation in a newborn?
- fetal RBC break down
- Relative deficiency of hepatocyte proteins and UDPGT
- High levels of β-glucuronidase in meconium
- minimal oral intake in first 2-4d –> slow excretion of meconium
What is breastfeeding jaundice?
Could be considered “lack-of-breastfeeding jaundice”.
Minimal oral intake → delayed passing of meconium → increased enterohepatic circulation.
Happens in the first week of life (esp with breastfeeding, as maternal milk comes in)
What is breast milk jaundice?
Not well understood; one theory is that breast milk has β-glucuronidase.
Begins in day 4-7, may not peak till day 10-14, and can persist up to 12w.
Bilirubin rarely reaches concerning levels.
What are the most forms of Ab-positive hemolysis?
Rh incompatibility, ABO incompatibility, and (much less common) incompatibilities with minor blood group antigens
What causes Ab-negative hemolysis in newborns?
- blood cell membrane defects (eg spherocytosis
- RBC enzyme defects (eg G6PD)
What are some causes of non-hemolytic RBC breakdown in a neonate?
- Extensive bruising from birth trauma
- Large cephalohematoma or other hemorrhage (e.g., intracranial)
- Polycythemia
- Swallowed blood (large amounts) during delivery.
What are TORCH infections?
(T)oxoplasmosis (O)ther Agents (R)ubella (C)ytomegalovirus (H)erpes Simplex
“Other” keeps getting added to – syphilis, varicella, coxsackievirus, HIV, parvovirus B19, some now say Zika
What in utero infectious exposure can lead to jaundice? What other findings might there be?
TORCH infections
May have hepatomegaly, microcephaly, and/or rash
What are some basic features of breastfeeding technique to assess?
- Mother’s comfort
- Baby’s latch, and vigour in feeding
- Problems with breathing, choking, or spitting up
How often does a breastfed baby nurse?
8-12 times in 24h
How long do feedings last (of breastfeeding)?
Initially up to 60min, but gradually shorter to about 20-30min (10-15min each breast)
What are some benefits to infants of breastfeeding?
- Maternal-infant bonding
- Protection against some infections (e.g. otitis media, respiratory infections, diarrhea)
- Reduced rates of SIDS
- Reduced rates of some allergic reactions
What are some benefits to mothers of breastfeeding?
- Decreased postpartum bleeding and more rapid uterine involution
- Lactational amenorrhea and delayed resumption of ovulation
- Earlier return to pre-pregnant weight
- Improved bone remineralization postpartum (reduction in hip fractures in the postmenopausal period)
Why is it important that the infant empty one breast before taking the other?
Lipid concentration in breast milk increases as the nursing episode proceeds
What are some common breastfeeding problems?
- enlarged, tender breasts
- improper latch or suckle
- prolonged feedings
- infants falling asleep before finishing
- maternal anxiety
What are some common reasons for enlarged, tender breasts in a breastfeeding woman?
engorgement
mastitis
plugged ducts (galactocele)
What group of conditions, though causing hemolysis, is not commonly associated with neonatal jaundice?
Hemoglobinopathies (eg the thalassemias, sickle cell)
What is the most common enzyme problem affecting red blood cell metabolism worldwide?
G6PD deficiency (Glucose-6-phosphate dehydrogenase)
What is the inheritance pattern of G6PD deficiency, and in what populations is it most prevalent?
X-linked recessive
Mediterranean or West African origin
What food should not be consumed while nursing an infant with G6PD deficiency?
Fava beans!
In areas where it is very prevalent, consider warning parents
What is biliary atresia?
Obstruction of the biliary tree due to progressive sclerosis of the extrahepatic bile duct
Seen in neonates
What are presenting symptoms of biliary atresia?
jaundice
dark urine
acholic stools
between three and six weeks of age
Any infant who develops jaundice after 2w must have bilirubin assessed
What is the treatment for biliary atresia?
Surgery
If done early, can restore flow and prevent liver damage
(Kasai procedure: anastomosis of the intrahepatic bile ducts to a loop of intestine to allow bile to drain directly into the intestine)
What is the urination pattern in a 3d infant? 6d infant?
3d: 4-6 per day
6d: 6-8 per day
Urine should be pale yellow
What is the stool pattern in a 3d infant? 6-7d?
3d: No more meconium, & stools should start to appear yellow
6-7d: Most have 3-4 stools/day, many pass stool with each feeding, and some stool as little as 1/wk (with breastfeeding)
Stool from breastfed infants has little odor
If an infant’s stool gradually loses colour and becomes more pale, what might this indicate?
Biliary atresia
What does “acholic” mean?
“without bile” – in context of stool, pale or clay-coloured
Should breastfeeding be ceased or paused in jaundiced infants?
No
Some clinicians will recommend 24-48h pause, but not AAP
Which newborns should be assessed for risk of hyperbilirubinemia before discharge?
All: Canadian Peds Soc says, Either TSB (total serum bilirubin) or TcB (transcutaneous bilirubin) concentration should be measured in all infants during the first 72 h of life
What supplementation should breastfed infants receive?
Vitamin D 400 IU daily
Canadian Paediatric Society recommends 800 IU intake per day – from all sources – between October and April depending upon where the family lives
How much of birth weight do breastfed neonates lose, and in what time frame?
7-10% in the first 4-5d
By what time should breastfed infants have regained their birth weight?
Two weeks
What is a caput succedaneum?
Edematous swelling over the presenting portion of the scalp of an infant
Commonly seen in babies born vaginally in vertex position. Because the scalp overlies the periosteum, this boggy swelling crosses suture lines. The swelling consists of serum
What is a cephalohematoma?
subperiosteal hemorrhage that is localized to the cranial bone that was traumatized during delivery. Does not extend across a suture line
What features on exam might suggest birth trauma leading to hyperbilirubinemia?
Any indication of bleeding, eg cephalohematoma, bruising
What surprising breast findings can be normal in a neonate?
A term infant may have 0.5–1.0 cm of palpable breast tissue.
Unilateral or bilateral engorgement of the breasts can occur in both male and female infants within several days and last for several weeks.
The breasts may even have a colostrum-like secretion.
What is normal liver edge finding in a newborn?
Palpable 1 cm below the inferior costal margin
What features exclude Dx of breastfeeding jaundice?
Weight, feeding, and stooling history indicating adequate breast milk
In what time frame does ABO incompatibility cause jaundice?
Within the first 24h of life
In an infant presenting with jaundice where the suspected diagnosis is breast milk jaundice, what labs are critical to order?
Total serum bilirubin
If persists, consider direct bilirubin
CBC not necessary: can exclude based on timing, Hx, and exam.
What is the MOA of phototherapy?
Light energy is absorbed by the bilirubin molecule →
stereochemical change that makes the bilirubin molecule more water-soluble →
excreted in the bile (without conjugation)
What determines the effectiveness of phototherapy?
- wave length
- irradiance (energy output)
- surface area of the infant’s skin exposed to the light.
Is sunlight an acceptable form of phototherapy?
No
When is phototherapy indicated?
In high risk hyperbilirubinemia (corresponding bilirubin level changes over the first week of life)
What fraction of healthy breastfed babies have persistent jaundice at 2w?
Almost 1/3
What is important to check in an infant with persistent jaundice?
Either dark urine or acholic stools
Also, reasonable to obtain total and direct bilirubin (make sure it is not climbing)
If barely noticeable at 2w, may consider observation alone
Explain conjugated and unconjugated bilirubin
Conjugated bilirubin = not bound to albumin. (Conjugated to a sugar, glucuronic acid.) Water soluble.
Unconjugated bilirubin = bound to albumin. Not water soluble alone.
Explain direct and indirect bilirubin
Direct bilirubin measures “directly” the water-soluble bilirubin. This is largely conjugated bilirubin, but up to 25% of result can be unconjugated; also, some conjugated binds to itself so it’s not accounted for
Total bilirubin measures all the bilirubin, through a series of chemical reactions
Indirect bilirubin is calculated: total - direct
(largely matches unconjugated, but, not precisely)
In most pediatric clinical situations, how many generations should a family history cover?
3 generations: child, siblings, parents, aunts, uncles, cousins of child, grandparents
What are the most common features of infants with Down syndrome?
> 50% of infants with Down syndrome have:
- Upslanting palpebral fissures
- Small ears
- Flattened midface
- Epicanthal folds
- Redundant skin on back of neck
- Hypotonia (most consistent finding in infants with Down syndrome)
What are Brushfield spots?
White spots in the iris; relatively common finding among pt with Down syndrome
Name three reasons to do genetic testing
Pt with …
- clinical features of a known chromosome disorder (such as Down syndrome)
- a known genetic condition but with additional or more severe findings
- intellectual disability and other unusual findings (including short stature)
- an unrecognized malformation syndrome
- or, pt born stillborn with multiple malformations
True or false: Most babies with Down syndrome are born to mothers who are younger than 35 years of age.
True: there are more total pregnancies in younger women.
What is the incidence of Down syndrome in the US?
1 in 700
What is the clinical relevance of mosaicism to Down syndrome?
Down syndrome patients who are “mosaic” can vary widely in terms of their physical findings and cognitive impairment, depending on the percentage of normal and abnormal cells in important tissues; Clinical findings in mosaic Down syndrome can range from those of “classic” Down syndrome to virtually normal.
What referrals or evaluations are recommended within the first 10y of life for a child with Down syndrome?
- thyroid (annual)
- vision
- hearing
- cardiology
- first month: CBC for leukemoid reactions, or transient myeloproliferative disorders
- at 1y then annually: Hb & Hct for anemia (sometimes lower dietary iron than normal)
- regular history & physical to assess atlantoaxial instability
- Referral to early intervention: early intervention is key!
What can atlantoaxial instability result in?
Spinal cord impingement
What are prenatal diagnostic tests for Down syndrome?
Amniocentesis and chorionic villus sampling
What is Fragile X syndrome?
Familial (genetic) syndrome that leads to intellectual disability and behavioural disorders. Result of a trinucleotide expansion on the X chromosome.
How common is fragile X syndrome?
1 in 4000 males
What are the physical findings of fragile X syndrome in girls?
Ranges. Asymptomatic - intellectual disability, psych/behaviour problems
What does the size of the trinucleotide expansion imply, in fragile X syndrome?
- some correlation between the severity of the intellectual disability and the size of the expansion
- mother may have pre-mutation (52-500 repeats; syndrome is clinical in >200 repeats usually)
What physical findings can often be noted at birth in a child with Turner syndrome?
Webbed neck Low ear placement Edema of the hands and feet Hyperconvex nails "Shield" chest, with widely spaced nipples
What is the incidence of Turner syndrome? What is the estimated miscarriage rate?
1/2000 live female births
99% of conceptuses are thought to miscarry
Name three common trisomies
Trisomy 13 (Patau syndrome) Trisomy 18 (Edward syndrome) Trisomy 21 (Down syndrome)
What are clinical presenting Sx of acute leukemia?
Fatigue
Decreased appetite
Anemia
Hepatosplenomegaly
What cardiac abnormality is seen in 35% of pt with Turner’s?
Coarctation of the aorta
What is the most common cardiac abnormality in pt with Down syndrome?
endocardial cushion defects: any of
- ventricular septal defect
- atrial septal defect
- complete atrioventricular canal defect
What are the physical findings of fragile X syndrome in boys?
M: intellectual disability, large ears, long face and mandible and, after puberty, large testicles.
May have evidence of a mild connective tissue abnormality (joint laxity, pectus excavatum, flat feet).
True or false: Fragile X syndrome is often diagnosed at birth
False: The findings in early childhood can be subtle.
True or false: Klinefelter syndrome is often diagnosed at birth
False: may not be diagnosed until adulthood
What is the clinical presentation and incidence of Trisomy 18?
Severe intellectual disability Prominent occiput Micrognathia Low-set ears Short neck Overlapping fingers Heart defects Renal malformations Limited hip abduction Rocker-bottom feet
1 in 6,000 births
(Edwards syndrome)
What is the clinical presentation and incidence of Trisomy 13?
Microphthalmia Microcephaly
Severe intellectual disability Polydactyly
Cleft lip and palate
Cardiac and renal defects Umbilical hernias
Cutis aplasia
1 in 10,000 births
(Patau syndrome)
What is an epicanthal fold?
skin fold of the upper eyelid covering the inner corner of the eye. It is often seen as a normal finding in very young children and is also common in people of Asiatic decent.
What are upslanting palpebral fissures?
A line drawn from the inner corner to the outer corner determines the slant of the eye, or palpebral slant – so inferior medial/superior lateral sides are “upslanting”
What are palpebral fissures?
In simple terms, refers to the opening between the eye lids
What are early signs of infant hunger?
Increased alertness
Increased physical activity
Mouthing
Rooting
What is the main way to assess if feeding is adequate?
If the infant is gaining weight
What does urine output imply about adequacy of breastfeeding?
Breast milk is predominantly water, so urine output is a good way to assess feeding
What is lethargy, in a child?
Lower level of consciousness. Characterized by the failure of a child to recognize parents or to interact with persons or objects in the environment
(The younger the child, the more difficult to assess for lethargy)
What is listlessness, in a child?
Child shows no interest in what is happening around herself
True or false: ankle clonus is normal in newborns, but not in children 1-2mo
Ankle clonus of up to 10 beats is normal in a newborn if it is symmetric and there are no other neuro signs (True)
More than 3 beats of clonus is abnormal by 1-2mo
What is routinely administered to infants born in hospital?
Vitamin K (prevent bleeds) Erythromycin eye ointment (prevent infection → blindness)
What screening tests are routinely administered to infants born in hospital?
Newborn screen (metabolic, etc) Jaundice screen (bilirubin) Hearing screen
What are common findings in congenital hypothyroidism?
Feeding problems Decreased activity Constipation Prolonged jaundice Skin mottling Umbilical hernia
What are two signs of sepsis?
Poor feeding and decreased activity
Jaundice can be a sign of sepsis, but rarely in isolation
How does salt-losing CAH present?
lethargy, vomiting, and dehydration that can progress to shock.
What are the presenting signs of inborn errors of metabolism?
somnolence and poor feeding, usually followed by vomiting and lethargy
What is the timeline to presentation for inborn errors of metabolism?
Newborns appear well for at least the first 1-2 days of life but then become symptomatic due to the protein load in breast milk or formula
What are the presenting symptoms of polycythemia in infants?
Often asymptomatic.
If symptomatic:
- altered mental status
- poor feeding
- plethora
- acrocyanosis
- hyperbilirubinemia
What is acrocyanosis?
persistent, painless, symmetric cyanosis of the hands, feet, or face
(akron = tip)
When does polycythemia present, in infants?
First few hours to days of life
What is the DDx for a neonate with poor feeding and decreased activity?
Congenital hypothyroid Abusive head trauma Sepsis CAH Inborn error of metabolism Polycythemia
There are others, but are rare or would not present alone (e.g. HIE, Trisomy 21)
How do you measure fontanelles?
Length and width, then average the two to get “fontanelle size”
What is the average fontanelle size of newborns?
- 1cm
0. 6 and 3.6 are 2 std deviations off
What conditions are associated with large fontanelles?
Skeletal disorders (e.g., rickets, osteogenesis imperfecta)
Chromosomal abnormalities (e.g., Down syndrome)
Hypothyroidism
Malnutrition
Increased intracranial pressure
What conditions are associated with small fontanelles or premature closure?
Microcephaly
Craniosynostosis
Hyperthyroidism
A normal variant
What labs evaluate for CAH?
Serum sodium and potassium
What lab is commonly elevated in inborn errors of metabolism?
Serum ammonia
True or false: TSH is not a relevant tested in neonate
False: In congenital primary hypothyroidism, T4 is low and TSH elevated (test both)
What is the most common form of CAH?
21-OH deficiency
What is elevated in 21-OH deficiency?
17-OH progesterone
Why are XX children virilized, with 21-OH deficiency?
17-OH progesterone is diverted to the androgen pathway, resulting in excess androgens and virilization
What hormones are low in 21-OH deficiency?
Cortisol and aldosterone
What severe presentation can 21-OH deficiency lead to?
Salt-wasting: hyponatremia and hyperkalemia
May present with vomiting, dehydration, and shock
What are aldosterone’s actions in the kidney?
Causes sodium retention and potassium loss.
Transfer of sodium from the lumen of the distal tubule into the tubular cells in exchange for potassium and hydrogen
What is the most common cause of congenital hypothyroidism in North America?
Thyroid dysgenesis:
Aplasia
Hypoplasia, or
An ectopic gland (accounts for two thirds of thyroid dysgenesis).
What is the most common cause of congenital hypothyroidism worldwide?
Iodine deficiency
How does congenital hypothyroidism present?
Feeding problems Decreased activity Constipation Prolonged jaundice Skin mottling Umbilical hernia
What is the timeline of presentation with congenital hypothyroidism?
Most appear normal at birth because they have maternal thyroid hormone.
Can be up to several months before infants show signs.
What long-term complications can develop from congenital hypothyroidism?
Intellectual diability: CH is one of the most common preventable causes. The longer treatment is delayed, the greater the risk.
Also:
large tongue, hoarse cry and puffy myxedematous facies.
How are infants with suspected congenital hypothyroidism managed?
Newborns with a low T4 and elevated TSH on the newborn screen are considered to have CH until proven otherwise, and treated with levothyroxine while waiting for confirmatory serum T4 and TSH
What is phenylketonuria (PKU)?
Phenylketonuria is a disorder of amino acid metabolism.
Caused by elevated serum phenylalanine; primary cause is deficient phenylalanine hydroxylase activity.
What is the treatment of phenylketonuria?
Diet low in phenylalanine
which is in all natural proteins
What are the main characteristics of the clinical syndrome phenylketonuria (PKU) causes?
Causes a clinical syndrome of intellectual disability with cognitive and behavioral abnormalities.
What is maple syrup urine disease?
a group of autosomal recessive disorders caused by deficiency in enzyme for amino acids
What is the incidence of maple syrup urine disease?
Overall quite rare, but significant (perhaps 1/200 births) in Mennonite populations.
What are the clinical manifestations of maple syrup urine disease?
Body fluid odour that smells like maple syrup
Overwhelming illness in the first days of life, beginning with vomiting and lethargy, and progressing to seizures, coma, and death if untreated
Milder forms: may only have Sx during stress (infection, surgery)
What is the treatment of maple syrup urine disease?
Dietary restriction
Acute: dialysis, hydration
Liver transplant is curative
What is galactosemia?
Carbohydrate metabolism disorder caused by inherited deficiencies in enzymes that convert galactose to glucose.
Symptoms and signs include hepatic and renal dysfunction, cognitive deficits, cataracts, and premature ovarian failure.
Name 3 congenital enzyme deficiencies that we screen for that can be rapidly fatal unless treated quickly
Maple syrup urine disease
Galactosemia
Congenital adrenal hyperplasia (salt-wasting)
What are the presenting signs of infant botulism?
hypotonia lethargy constipation absent DTRs weak cry Can eventually lead to respiratory failure.
What are the presenting symptoms of undiagnosed phenylketonuria?
vomiting, hypotonia, musty odor, developmental delay, and decreased pigmentation of the hair and eyes.
