Endocrine - to final

Question 0

Factors for head growth

Answer 0

= DIRECTLY determined by brain size

• • genetics, nutritional and environmental,
• NOT hormones (affect brain dvpt but not size)

Question 1

Factors in growth

Answer 1

1. genetics - complex, affects all other factors

2. nutritional - availability, intake, absorption, metabolism…
3. environmental - internal and external (physical AND psychosocial)
4. hormonal (insulin, IGF, thyroid, GH)

Question 2

Microcephaly

Answer 2

head size < 2.5 SD below mean for age & sex
*usually w/ abnormal brain structure
=> mental retardation, seizures, aud/visual deficits
*primary (at birth) or secondary (fall off growth curve)

Question 3

Macrocephaly

Answer 3

Head size >2.5 SD from mean for age & sex,

Some causes: hydrocephalus, subdural effusion, hematoma, genetic syndromes/familial trends

Question 4

Factors influencing weight in infants/children

Answer 4

(all 4)

genetics, nutrition, environment, and hormones

Question 5

Short stature

Answer 5

height >2.5 SD below mean for age & sex

* most common reason for referral, usually a normal variant (vs. pathological)

Question 6

Genetic short stature

Answer 6

normal variant of short stature,
within midparental height range prediction.
- normal birth size, slow growth 6 mo - 3 yrs
- normal growth velocity 4 yrs - puberty
* bone age = chronological age

Question 7

Constitutional Delay of Growth

Answer 7

“Late bloomers,” = normal variant of short stature, normal final height.

• normal birth size,
• deceleration in weight gain 6 mo - 3 yrs
• normal growth rate 4 yrs - puberty, but puberty occurs at later age.
• bone age delayed (-1 to -3 SD)

Question 8

Genetic etiologies of pathologic short stature

Answer 8

1. Chromosomal macrodeletions/duplications (Turner’s = 45 XO, Down syndrome, other trisomies)
2. Chromosomal microdeletions/mutations
   (intrauterine growth retardation, metabolic pathway defects)

Question 9

Intrauterine Growth Restriction

Answer 9

• Nonspecific: maternal factors, poor nutrition, infection (CMV, rubella, toxoplasmosis), toxins (EtOH, cigarettes)
• Specific: rare, usually genetic. w/ dymorphic features, +/- mental retardation. *if going to catch up, will by 9-12 mo.!

Question 10

normal height velocity cut-offs for age (below this is concerning)

Answer 10

0-1 yr: 11 cm/yr
1-2 yrs: 7 cm/yr
2-3 yrs: 5 cm/yr
4-puberty: 4.5 cm/yr
puberty: 5.5 cm/yr

Question 11

Normal variants of short stature

Answer 11

1. genetic
2. constitutional growth delay
   * may be both factors.

Question 12

Characteristics of genetic short stature

Answer 12

• short family,
• slow growth - 3yrs, normal after;
  normal bone age
  puberty at normal age

Question 13

characteristics of Constitutional delay –> short stature

Answer 13

• low weight gain to age 3, normal growth velocity 4-puberty
• delayed puberty
• bone age -1 to -3 (less if combined w/ genetic short stature)
  normal end height

Question 14

Non-specific causes of intrauterine growth restriction

Answer 14

1. maternal factors
2. poor nutrition
3. infection (CMV, rubella, toxoplasmosis)
4. toxins (EtOH, cigarettes)

Question 15

environmental factors for short stature

Answer 15

internal - chronic disease

external – psychosocial, chronic drugs (glucocorticoids, steroids)

Question 16

growth effects of congenital hypothyroidism

Answer 16

normal fetal weight, length;

* delayed skeletal maturation, and brain if prolonged in utero

Question 17

Acquired hypothyroidism – effect on growth

Answer 17

NO mental retardation if after age 3-5;

• linear growth and skeletal maturation profoundly decreased during disease (abrupt halt on growth curve!)
  also: fatigue, lack of energy

Question 18

when to evaluate for GH deficiency/pathological short stature

Answer 18

1. height < 1st percentile
2. height velocity < 4 cm/yr
3. bone age 2+ SDs from mean

Question 19

How to work up GH deficiency

Answer 19

1. check thyroid
2. GH response test to 2 diff stimuli! (GH <10 ng/mL= deficit)
3. look for response to GH replacement

Question 20

possible etiologies for GH resistance

Answer 20

• GH R absent/abnormal (Laron syndrome)
• STAT5B mut (signal transduction -> interrupted Jak/STAT cascade)
• IGF-1 or IGFBP3 or ALS gene deficits
• “ALS” = Acid Labile Subunit
• • IGF-1 gene def => sensorineural hearing loss & other Sxs**

Question 21

non-endocrine causes of pathological tall stature

Answer 21

1. cerebral gigantism
2. Marfans
3. homocysteinuria
   * Obese children (increased nutrition, but final height = ~normal)

Question 22

Endocrine causes of pathological tall stature

Answer 22

1. Precocious sexual dvpt –> early puberty, higher velocity before puberty. **usually end up ~short compared to peers!
2. GH excess (gigantism/acromegaly)
3. Gonadal steroid deficit –> longer pre-pubertal stage (extra growth), *failure of epiphyses to close!

Question 23

Craniosynostosis

Answer 23

premature closure of skull suture(s) –> only cosmetic problem if 1 (multiple = more growth limitation)

Question 24

organic causes of childhood obesity

Answer 24

= VERY rare (<0.1%!) * will have low GHBP

1. genetic, hypothalamic dysfunction
2. glucocorticoid excess
3. insulin excess
   * hypothyroidism: weight disproportionate to height, but not excessive

Question 25

Failure to thrive

Answer 25

= lack of weight gain, but continued head circumference growth.
95% bc insuff. nutrition
…others: malabsorption, chronic disease, genetic, etc.

Question 26

Prenatal growth hormones

Answer 26

MANY (IGF-2, FGF, CGF, NGF, etc.)… but NOT GH or TH

Question 27

IGF binding proteins

Answer 27

IGFBP-1: regulates IGF-1 in utero
IGFBP-2: high in fetus
IGFBP-3: most important post-natal, GH/IGF-dep. synthesis

Question 28

ALS (Acid Labile Subunit)

Answer 28

binding protein that forms ternary circulating complex with IGF-1 & IGFBP-3

• synthesized in liver
• maintains circulating IGF-1, but no effect on IGF synthesis