Gastrointestinal/Nutrition Flashcards
Prenatal lab finding in gastroschisis
Elevated maternal serum AFP or amniotic AFP (alpha-fetoprotein)
Classic presentation of pyloric stenosis (age, symptoms and signs)
1 month, non-bilious projectile emesis, hypochloremic/hypokalemic metabolic alkalosis and “olive” epigastric mass
Components of a cloaca
Urinary, vaginal, rectal fusion
Muscularization of esophagus (which parts are what type)
Upper: striated
Middle: striated and smooth
Lower: smooth
Cause of distal (jejunoileal) atresias
Vascular disruption leading to ischemic areas that underdevelop
Common prenatal and postnatal findings in TEF
Prenatal: polyhydramnios
Postnatal: pooling oral secretions, inability to pass NG (but presence of distal bowel gas)
Sequelae of 1) significant ileal resection and 2) loss of terminal ileum
1) Fat malabsorption due to severely decreased bile salt recycling (almost all hepatoenteric circulation is in ileum)
2) “Short gut” from faster gastric emptying/intestinal motility
Protein that, if deficient/absent, leads to fat malabsorption
Betalipoprotein
What is an epignathus?
Teratoma of upper palate or jaw, benign but can cause obstruction
Remember -gnathus/-gnathia has to do with the jaw
Treatment is excision
(sciencedirect.com)
The midgut loops in the ______ direction around the _____
Counter-clockwise
Superior mesenteric artery
Main cause of carbohydrate malabsorption
Congenital sucrase-isomaltase deficiency (CSID), an enzyme that breaks down those disaccharides in the small intestine
Defect that causes positive stool reducing substances that’s associated with inability for blood glucose to respond to normal feeds and/or dextrose gel
Sodium-glucose linked transport protein (SGLT) defect
Transport protein defect leading to carbohydrate malabsorption very rare (more commonly enzyme-related)
Laboratory finding (that’s non-diagnostic) in milk protein allergy
High cow’s milk IgE, relates to it being an immunologic hypersensitivity (does usually resolve by school age)
Histologic findings on rectal biospy in Hirschsprungs (2)
1) Aganglionosis in the myenteric and submucosal plexuses
2) Increased acetylcholinesterase (AChE) within hypertrophic cholinergic nerve fibers
Components of GALT (gut-associated lymphoid tissue) and their functions
1) Peyer patches—sites of T and B cell activity
2) Lamina propia plasma cells—make IgA (neutralize bacteria)
Gastroschisis is almost always on the ______ side of the umbilical cord and is associated with ______
Right
Rarely associated with anything, but IF it is it’s almost always another GI anomaly (like atresia)
What is a congenital epulis?
Benign granular cell tumor, comes from gingival or alveolar mucosa
(sciencedirect.com)
What is deficient in a patient with watery/foul stools, retinitis pigmentosa, and neuromuscular degeneration?
ncbi.nlm.nih.gov
Apolipoprotein beta (leading to fat malabsorption)
Rarely can be Anderson disease (lipoprotein assembly defect)
Primary job of colon
Water and electrolyte reabsorption
Concomitant allergy with MPA (milk protein allergy)
About 50% also allergic to soy
What causes proximal GI atresias
Failure of recanalization of the primitive gut tube around 10 weeks gestation
(Remember TEFs are around 4 weeks when 2 tubes separate, then 8-10 weeks is when tubes recanalize)
Main risk factors for small left colon/meconium plug syndrome
Maternal diabetes
Prematurity
Normal lower esophageal sphincter tone in neonate vs. 6-month-old
2mm Hg vs. 10-15mm Hg
Which abdominal wall defect is affiliated with other congenital anomalies [more frequently]?
Omphalocele
VACTERL, Trisomies, and Beckwith-Wiedemann all associated and can involved kidneys and heart
Secondary carbohydrate enzyme deficiency seen with CSID (congenital sucrase-isomaltase deficiency)
Maltase-glucoamylase deficiency (MGA), because they are homologous enzymes
What provides stimulation of the fundus and proximal stomach
Vagus nerve
Esophageal duplication cysts are diagnosed by _____, but require ____ to confirm they’re not ______ that would communicate with CNS
CT
MRI
neurenteric cyst
Chromosome that most syndromes involving pancreatic insufficiency trace back to
7
Schwachman-Diamond involves mutations of 7q11 and Cystic Fibrosis of CFTR on 7
The other GI organs form from the ____ of the primitive gut tube
Endoderm (pancreas, liver)
Two syndromes frequently associated with TEF
VACTERL (vertebral anomalies, anorectal anomalies, cardiac defects, tracheoesophageal defects, renal, limb anomalies)
CHARGE (coloboma, heart defect, atresia choanae, restricted growth, genital, ear anomalies)
70% of TEFs will have at least one other anomaly
Most common type of tracheoesophageal fistula
Type C: proximal esophageal atresia with a distal fistula
(sciencedirect.com)
Embryonic/cellular cause of Hirschsprung’s
Vagal neural crest cells don’t migrate correctly to anus +/- rectum, leads to aganglionic segment
The earlier they stop [migrating], the longer the segment
Frequency of milk protein allergy and percentage that can later tolerate cow’s milk by ages 2 and 6.
5% in neonatal period (only 0.5% are breastfed)
30% can tolerate cow’s milk by age 2, 80% by age 6
Longterm risk if a choledochal cyst is not removed
Malignancy
Gender predominance of:
- Gastroschisis
- Choledochal cyst
- Imperforate anus
- NONE (omphalocele, however, has male predominance)
- Female
- Male
Alagille syndrome:
- Pathology
- Mutations
- Inheritance pattern
- Paucity of INTRAhepatic/intralobular bile ducts
- JAG1 and NOTCH2
- Autosomal dominant (less common than biliary atresia)
Frequent findings in Alagille syndrome
Renal
Cardiac (Tetralogy of Fallot and peripheral pulmonic stenosis [PPS])
Butterfly vertebrae
Triangular “shield” facies and embryotoxon (“iris strands”, faint stranding around circumference)
Best timeframe to perform Kasai in biliary atresia
First two months
Ultrasound findings suggestive of biliary atresia
Absent gallbladder (presence of one does NOT rule out BA)
“Triangular cord sign”, a fibrous remnant of extrahepatic bile duct anterior to portal vein
(radiopaedia.com)
Laboratory findings in alpha-1 antitrypsinogen deficiency (A1AT, AATD, A1AD)–a serine protease inhibitor made in hepatocytes
Cholestasis
High GGT
Low A1AT
A1AT deficiency leads to COPD/pulmonary disease in adults
What endocrine disorders commonly present at cholestasis?
Hypothyroidism
Panhypopituarism
- Enzyme responsible for conversion of heme to biliverdin
- Enzyme responsible for conversion of biliverdin to unconjugated bilirubin
- Heme oxygenase
- Bilirubin reductase
- Location of conversion of heme to biliverdin and then unconjugated bilirubin
- Primary binder of bilirubin in circulation
- Primary carrier of bilirubin from plasma into hepatocytes
- Hepatocytes
- Albumin
- Ligandin
List three reasons that bilirubin accumulates more in newborns
- Increased RBC turnover (average life span 60d)
- Decreased UDP-glucuronyl transferase (responsible for conjugation)
- Increased enterohepatic circulation (so its reabsorbed from intestine more)
Areas of brain most affected by kernicterus
- Basal ganglia (especially globus pallidus)
- Hippocampus
- Cranial nerve nuclei
(These are the reasons that choreoathetosis/cerebral palsy, upward gaze palsy, and deafness are sequelae)
Enzyme responsible for conversion to conjugated bilirubin
Uridine diphosphate-glucuronyl transferase (UDP-glucuronyl transferase) in hepatocytes
(Conjugated is water-soluble, then excreted in bile and secreted into intestines)
What is the neurotoxic form of bilirubin?
Unbound circulating unconjugated
(Vast majority bound to albumin, which cannot cross blood-brain barrier–this is the reason albumin:bilirubin ratio is important)
Extraneural manifestations of severe bilirubin toxicity
Renal, intestinal mucosa, and pancreatic necrosis
Non-intrinsic risk factors that increase bilirubin toxicity (AKA other pathologies/abnormalities)
Hypoxia
Acidosis
Hyperosmolarity (hypernatremia, dehydration)
Asphyxia
Complications of double-volume exchange transfusion
Portal vein and renal vein thrombosis
Necrotizing enterocolitis
Thrombocytopenia
Hypocalcemia (due to binding from citrate anticoagulant in pRBCs)
Which presents earlier, breastmilk or breastfeeding jaundice?
Breastfeeding (the pathologic one); breastmilk jaundice is more 1-2 week timeframe
(Most commonly cited cause for breastmilk jaundice is increased beta-glucuronidase which deconjugates intestinal bilirubin, increasing reuptake)
What are some evidence-based iatrogenic risk factors for ELBW infants to develop necrotizing enterocolitis (NEC)?
Prolonged antibiotic exposure, in the study defined as 5 or more days
Formula
(Rapid feed advancement is believed to be a risk, but not defined or fully proven)
What are the normal sodium and potassium requirements for preterm neonates?
Sodium: 3-7 mEq/kg/day
Potassium: 2-5 mEq/kg/day
Which of the three nutrient groups has predominantly normal enzyme levels at birth?
Carbohydrates: Glucosidases are normal level by term
For preemies lactase is deficient but contained in breastmilk
What organ contributes to the second step in protein digestion
The pancreas: trypsin and chymotrypsin, which are severely deficient in preterm (and even term only have 25% of adult activity)
Breastmilk has these (and others) to make up for low levels
What are the first two steps in fat digestion and what organs help
Bile salts (liver) form micelles
Pancreatic lipase hydrolyzes them into absorptive pieces
Both decreased in preemies but lingual/gastric and beastmilk lipase help
Which types of fatty acids do NOT require bile salts
Short- and medium-chain
This is why patients with cholestasis/liver disease do best with MCT supplementation
Why does it matter that glucose and galactose are absorbed via active transport (from intestine)
This is inefficient the earlier in gestation, one of many reasons for hypoglycemia
What transporter do all monosaccharides go through to enter circulation
GLUT2 transporter
Of the two–digestion and absorption–which one tends to be less efficient in newborns
Digestion
Enzymes tend to be at low levels but transporters normal (exception is the active transport of glucose/galactose)
Beckwith-Wiedemann is associated with what two GI anomalies
Omphalocele
Malrotation
___% of patients with meconium ileus have _______
90% of patients with meconeum ileus have Cystic Fibrosis
(It’s usually obstructive at the terminal ileum)
What should you think of for an otherwise well baby who develops acute enterocolitis (foul-smelling bloody stools, NEC-like picture)
Hirschsprung’s disease
Rare but if occurs has around same mortality rate as preemie NEC (30%)
No _P_arasympathetic innervation to _P_oop (most are only rectosigmoid)
Week of gestation of 1) TEF and 2) Hirschsprung’s
TEF: Four (embryonic stage for lungs, two tubes don’t separate correctly)
Hirschsprung’s: Eight
If you see pyloric stenosis on an XR, what names is the sign given?
String sign or apple core (from the contrast leaking through I highly narrowed segment)
Omphalocele and gastroschisis associations
Omphalocele: Beckwith-Wiedemann, Trisomies, OEIS
Gastroschisis: almost n**one
Name the most common intra- and extra-hepatic causes of cholestasis
Intra: idiopathic neonatal cholestasis
Extra: biliary atresia
Consider what diagnosis in a jaundiced infant with acholic stools and a palpable mass near the RUQ
Choledochal cyst
(EXTRA hepatic cause, most easily diagnosed with ultrasound)
Mutations associated with Allagille Syndrome
JAG1 or NOTCH2
What is the estimated energy requirement to grow for an LBW neonate?
100-130 kcal/kg/day (90-120 is estimated “need” but higher-end for growth)
How much of the energy (calories) is fat in human milk or formula
50%
Most common fatty acids are SOaP=Stearic, Oleic and Palmitic
Which two fatty acids are essential in all neonates? Which two are hard for preemies to synthesize?
1) Linoleic and linolenic acid
2) docohexanoic acid (DHA) and arachidonic acid (ARA)
What percentage of the energy in human milk are carbohydrates and protein
40% carbohydrates
10% protein
(fat is 50%)
The predominant forms of fatty acids, carbohydrate, and protein in breastmilk
Fatty acids: Stearic, Oleic, and Palmitic (SOaP)
Carbohydrate: Lactose
Protein: Beta-casein (although for general groups, whey>casein)
What is the main fetal energy source and how is it delivered
Maternal glucose by facilitated diffusion (passive, requires no ATP)
The other two sources are maternal lactate and amino acids
Four amino acids essential in premature infants (per Brodsky)
CATT:
Cysteine
Arginine
Tyrosine
Taurine
How do whey:casein change as milk production continues
In colostrum whey:casein is 80:20, then ends up being around 50:50 with beta-casein being the main protein form
How many calories come from 1g of fat, carbohydrate and protein
20% IL: 9kcal/g
CHO: 3.4kcal/g
AA: 4kcal/g
These are listed in order of how much they contribute to ENTERAL nutrition compositin; in TPN CHO > FAs >> AA
What amino acid is most important in fatty acid metabolism
Carnitine
This is why you add it in TPN cholestasis and why you supplement it in fatty acid oxidation defects
Both vitamin ____ deficiencies and EFAD cause _____ as a main presenting symptom
Vitamins B (B2, B3, B6)
EFAD: essential fatty acid disorder from lack of linoleic and linolenic acid
Dermatitis
Two main drugs/classes that cause bilirubin dissociation
Ceftriaxone
Sulfa
(Matters because they compete for albumin binding, and only unconjugated unbound albumin crosses the blood-brain barrier)
Mechanism of phototherapy
Photoisomerization of unconjugated bilirubin to lumirubin, which is water-soluble and leaves in bile/urine
Name three important proteins and enzymes in bilirubin metabolism
Albumin: binds unconjugated bilirubin to safely transport to liver
Ligandin: transport molecule from plasma into liver
UDP-glucuronosyltransferase (UDPGT): enzyme that conjugates bilirubin
(UDGPT only 1% of adult function at birth)
Gilbert Syndrome facts
1) UGT1A1 mutation: decreased expression of UDPGT
2) less glucoronc acid conjugation means higher unconjugated bilirubin; usuallu just at times of stress
Genetic syndrome that causes dysfunction of UDPGT
Crigler-Najjar
(Unconjugated hyperbilirubinemia beyond first 2 weeks of life, severe form requires liver transplant)
As gestational age increases, what happens to 1) total body water, 2) extracellular water and 3) intracellular water
As gestational age increases, TBW and extracellular water decrease
Intracellular water increases (cells are hypertrophic at this phase, not increasing in number)
Sequelae of Copper deficiency
Anemia
Leukopenia
Myeloneuropathy
Sequelae of Selenium deficiency
Cardiomyopathy
What is the respiratory consequence of giving excess carbohydrates
Excess CO2 production (ie increased Respiratory Quotient)
Keep ratio CHO:IL 60:40 in terms of calorie contribution (and maximum GIR 13)
Why is it that carbohydrate excess increases the RQ (respiratory quotient)
Converting CHO to fat is energy inefficient, results in more CO2 byproduct
What enzymes does the stomach produce to start protein digestion
Pepsin and gastrin
How glucose is absorbed in the GI tract
Facilitated diffusion
Also true for glucose to cross placenta
Name the deficiency: Scaling dermatitis, alopecia, thrombocytopenia, increased susceptibility to infections
Essential fatty acid disorder (EFAD) Presents very similarly to Biotin deficiency (especially kind of dermatitis) but thrombocytopenia helps tell them apart Occurs if getting <0.5g/kg/day of IL
Name the deficiency: Photophobia, abnormal enamel formation, abnormal epiphyses
Vitamin A Also important for pulmonary epithelial growth (remember it’s proven to decrease BPD!)
Name the deficiency: Megaloblastic macrocytic anemia, maternal vegetarian diet
Vitamin B12 (cobalamin) deficiency Supplement with methylmalonic acidemia
Name the deficiency: Megaloblastic macrocytic anemia, failure to thrive, goat’s milk diet
Folate deficiency Remember to supplement in homocystinuria
Name the deficiency: Osteopenia/Rickets, failure to thrive
Vitamin D Remember, vitamin D is NOT required for maternal transfer of Ca to fetus (increased intestinal absorption in her is completely independent of vit D!)
In TPN-associated cholestasis, what two trace elements are decreased
Manganese and Copper
