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a_ARTS > 11/9- Pediatric Endocrinology > Flashcards

11/9- Pediatric Endocrinology Flashcards

1
Q

Describe the Texas Newborn Screen

  • When is 1st sample drawn?
  • Second sample?
A
  • 1st sample: between 24-48 hrs
  • 2nd sample: 10-14 days
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2
Q

What diseases/conditions are tests for in the Texas Newborn Screen?

A
  • PKU (phenylketonuria)
  • GALT (galactosemia)
  • CH (congenital hypothyroidism)
  • Hemoglobinopathies
  • CAH (congenital adrenal hyperplasia)
  • Newborn hearing screen (not blood spot…)
  • BIOT (biotinodase)
  • CF (cystic fibrosis) NOW…. there are A BUNCH (19)
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3
Q

Describe the hypothalamus-pituitary-thryroid axis?

What is the relations to pediatric endocrinology

A

Relevant b/c congenital hypothyroidism is screened in newborns

  • Hypothalamus: TRH
  • Ant pituitary: TSH
  • Thyroid: T3, T4
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4
Q

What is thyroid hormone responsible for (especially in newborns/pediatrics)?

A
  • Brain development
  • Growth and skeletal development
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5
Q

What happens in congenital hypothyroidism (signs/symptoms)?

A
  • Delayed epiphyseal development
  • Poor growth
  • Delayed Puberty
  • Poor Healing (decreased metabolic efficacy)
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6
Q

Describe congenital hypothyroidism

  • Prevalence
  • Gender
  • Results in
  • Etiology
  • Assocations
A
  • 1/2000 newborns
  • 2x females
  • One of the most common preventable causes of intellectual disability (mental retardation)
  • Inverse relationship between age at clinical diagnosis and treatment initiation and intelligence quotient (IQ) later in life
  • Most common cause of congenital hypothyroidism is some form of thyroid dysgenesis (agenesis, hypoplasia, or ectopy)
  • Higher incidence in children with Down Syndrome
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7
Q

T/F: most newborns with the disease have signs/symptoms of congenital hypothyroidism

A

False; >95% have no signs/symptoms (mom hormones are enough)

  • Many have birth weight and length in normal range
  • Maternal T4 crosses the placenta if present in circulation
  • Mom’s T4 plus small amount of native thyroid function can keep clinical signs and symptoms hidden
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8
Q

Describe thryoid tissue in neonates with congenital hypothyroidism

A

Although inadequate, most neonates with congenital hypothyroidism have some small amount of functioning thyroid tissue

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9
Q

_____ was known to be a major cause of mental retardation

A

Sporadic neonatal hypothyroidsm was known to be a major cause of mental retardation

  • This was later found to be preventable (1950s)
  • Early diagnosis and treatment was recognized to be a crucial determinant of cognitive outcome in congenital hypothyroidism
  • Discovered before 3 mo: 75% IQ > 90
  • Discovered 4-6 mo: 33% IQ > 90
  • Discovered 7-24 mo: 40% IQ > 90
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10
Q

What are other signs/symptoms of congenital hypothyroidsim if untreated or severe in utero?

A
  • Constipation
  • Hypotonia
  • Hoarse cry
  • Macroglosia
  • Umbilical hernias
  • Large fontanelle
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11
Q

What are 3 common testing strategies of congenital hypothyroidism?

A
  • T4 assay only (this can miss maternal levels of T4 crossing the placenta)
  • TSH assay only (this can miss neonate thyroid function; may have really high TSH but no T4)
  • Simultaneous T4 and TSH assay

Texas only checks T4; this is why the 2nd newborn screen is so important. This level will have fallen by then)

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12
Q

How does Texas screen for congenital hypothyroidism specifically?

A

Texas only checks T4; this is why the 2nd newborn screen is so important. This level will have fallen by then

  • Lowest 10% of samples are considered abnormal
  • TSH sent if T3 is low and T4 repeated
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13
Q

Describe the HPA axis in terms of Congenital Adrenal Hyperplasia

A
  • CRH (hypothalamus)
  • ACTH (ant pituitary)
  • Cortisol (adrenal gland)

Abnormal cortisol production can contribute to ambiguous genitalia

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14
Q

>95% of CAH (congenital adrenal hyperplasia) is due to what?

A

21-hydroxylase deficiency

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15
Q

Describe 21-OHase deficiency

  • Causes what
  • Inheritance pattern
  • Prevalence
  • Forms and percentages
A
  • Causes >95% of CAH
  • Autosomal recessive inheritance
  • Occurs in 1/1400 live births

Forms:

  • 33% are Virilizing form (in girls; doesn’t happen in boys because excess testosterone in males does not change external genitalia)
  • 67% are Salt-Wasting form
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16
Q

Describe how undifferentiated genital features mature in male and female (genital tubercle, fold, and swelling)

A

Male:

  • Tubercle -> glans
  • Fold -> shaft of penis
  • Genital swelling -> scrotum

Female:

  • Tubercle -> clitoris
  • Fold -> labia minora
  • Genital swelling -> labia majora
17
Q

What are the big hormonal changes occurring with 21-OHase deficiency?

A
  • Excess testosterone (virilizing)
  • Deficient aldosterone (salt wasting)
18
Q

What should be done in expected 21-OHase deficiency?

How is it managed?

A
  • Physical exam
  • Pelvic US
  • Bladder
  • Uterus, Ovaries
  • Testes
  • Karyotype (or FISH)
  • 17-hydroxyprogesterone (17-OH-P): should be high/backed up
  • Serum electrolytes
  • Supplement glucocorticoid with hydrocortisone
  • Supplement mineralocorticoid with fludrocortisone
  • Stress dose hydrocortisone should be prescribed for times of illness!!
19
Q

Describe the presentation of CAH: salt-wasting form

  • Time of presentation
  • Presentations if untreated
A
  • Typically present between 7 - 14 days of life (but don’t exclude b/c you think it’s too early)
  • Undiagnosed or untreated affected children are likely to present with failure to thrive, and frequently present with:
  • Life-threatening dehydration
  • Hypotension
  • Acidosis
  • Hyponatremia
  • Hyperkalemia (risk of instant death)
  • Family education is vital to keeping children healthy
20
Q

The virilizing form of CAH is a _____ emergency

A

The virilizing form of CAH is a psycho-social emergency

  • Get ambiguous genitalia consult service (endocrinologist, geneticist, ethicist, surgeon/urologist)
21
Q

How to manage virilizing CAH cases?

A
  • Avoid using pronouns when talking about the baby
  • Birth certificate documentation should be postponed until family has decided on gender assignment.
22
Q

What are Current Guidelines from Lawson Wilkins Pediatric Endocrine Society and the European Society for Pediatric Research?

A
  • Virilized 46XX infants should be raised in the female role, given that more than 90% of these patients identify as females in adulthood - Reserve clitoral surgical treatment until the patient can make a mature decision.
  • However, early separation of the vagina and urethra is recommended (prevention of UTI that can be frequent with a urogenital sinus)
  • Decision for gender reassignment in fully masculinized individuals with an XX karyotype who are identified later in life, should be initiated by the patient and include careful consultation and psychological evaluation.
23
Q

What infant populations are at risk for hypoglycemia (neonatal hypoglycemia)?

  • Describe mechanisms
A
  • Infant of diabetic mother (IDM)
  • Mother’s blood brings extra glucose to fetus
  • Fetus makes more insulin to handle the extra glucose
  • Extra glucose gets stored as fat and fetus becomes larger than normal
  • Late preterm infants (LPT): 34-36(6/7) wks
  • Smaller
  • Livers are immature; not able to make/break down glycogen
  • Small for gestational age (SGA)
  • Don’t have sugar stores in liver
  • At birth, not receiving glucose from placenta
  • Large for gestational age (LGA)
  • Used to high caloric baseline
  • Have excess insulin in circulation after birth
24
Q

What’s so bad about neonatal hypoglycemia?

A

Persistent or recurrent hypoglycemia can result in:

  • Permanent brain injury and cognitive impairment
  • Vision disturbance
  • Generalized seizures or occipital lobe epilepsy
  • Cerebral palsy
25
Q

What is the glucose infusion rate? (don’t really need to know)

A

Glucose infusion rate (GIR)

  • Usual fluid is D10W (remember there are 10g of glucose/100mL water in D10W)
  • Remember that pedi fluid rate is given in mL/kg/d
  • There are 1,440 minutes in a day

GIR (mg/kg/min) = (conc)(rate)/144

GIR (144)/conc = rate

26
Q

How are babies with neonatal hypoglycemia evaluated?

A
  1. Check pre-prandial glucose if taking enteral feeds or Q3 checks if NPO on IVF
  2. Feed the baby! If not able to PO feed because of respiratory distress or prematurity…gavage feed
  3. IDM babies need to PO feed and re-set their insulin secretion
  4. If persistent hypoglycemia (needing GIR >10 for more than 7 days) consider other reasons for hypoglycemia…
27
Q

What is the etiology of neonatal hypoglycemia? (don’t memorize)

A
  • Hyperinsulinism: IDM/LGA, Islet cell hyperplasia, Beckwith-Weidermann syndrome, Insulin-producing tumors, Maternal tocolytic therapy (terbutaline), exogenous supply of insulin
  • Decreased production/stores: prematurity, delayed feeds
  • Abnormal glucose utilization/production: sepsis, shock, hypothermia, respiratory distress, abnormal glucose metabolism, defects in AA metabolism
28
Q

What is the work-up for neonatal hypoglycemia?

A
  • Insulin level
  • C-peptide
  • Growth hormone
  • Cortisol
  • Lactate
  • Ammonia
29
Q

What is the treatment for neonatal hypoglycemia?

A

Depends on etiology; can include:

  • Continued supplementation while attempting to wean to PO
  • Hydrocortisone
  • Glucagon
  • Diazoxide

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