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Neo Board Review MAP > Endocrinology > Flashcards

Endocrinology Flashcards

(88 cards)

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1
Q

Dominant neonatal thyroid hormone

A

T3

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2
Q

Thyroid hormone that is increased during times of critical illness among preterm infants

A

Reverse T3

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3
Q

Which hormone helps with male external genital development during the first trimester of pregnancy?

A

Placental hCG

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4
Q

Which hormone helps with male external general development after the 1st trimester of pregnancy?

A

LH

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5
Q

Osteomalacia

A

Normal osteoid production

Decreased mineralization

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6
Q

Which enzyme deficiencies cause ambiguous male genitalia?

A

17 a-hydroxylase deficiency
3 b-hydroxysteroid dehydrogenase deficiency
5 a-reductase deficiency

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7
Q

Which enzyme deficiencies cause ambiguous genitalia in females?

A

21 Hydroxylase deficiency
11 b-hydroxylase deficiency
3 b-hydroxysteroid dehydrogenase deficiency
Aromatase deficiency

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8
Q

When is the pituitary gland formed?

A

14 weeks gestation

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9
Q

What is the thyroid gland formed from?

A

Primitive pharyngeal floor and 4th pharyngobronchial pouch

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10
Q

When does the thyroid gland develop?

A

3-4 weeks gestation

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11
Q

When does iodide trapping begin?

A

8-10 Weeks gestation

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12
Q

When does T4 and T3 synthesis and secretion begin?

A

12 weeks gestation

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13
Q

Adequate quantities of ___ are essential for fetal thyroid hormone synthesis

A

Iodide

Fetus relies on transplacental transfer of iodine for supply

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14
Q

When does TSH secretion begin?

A

12 weeks gestation

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15
Q

Where is TRH produced during pregnancy?

A

Pancreas and hypothalamus until closer to term

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16
Q

When does TSH surge occur after birth?

A

Peaks at 30 minutes of life
Lasts 3 to 5 days
Due to being cold at birth

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17
Q

When do fetal T3 levels increase during pregnancy?

A

30 weeks

Thyroid gland able to convert T4 to T3 more effectively

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18
Q

Most common cause of congenital hypothyroidism?

A

Thyroid dysgenesis
No thyroid or it’s in the wrong place
1:4000

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19
Q

Causes of congenital hypothyroidism

A

Thyroid dysgenesis
Thyroid dyshormonogenesis 1:40000
Central hypothyroidism 1:100000
Transient hypothyroidism 1:40000

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20
Q

Causes of thyroid dyshormonogenesis

A

TSH unresponsiveness
Iodide trapping defect
Organization defect
Iodotyrosine deiodinase deficiency

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21
Q

Symptoms of congenital hypothyroidism

A 
Enlarged posterior fontanelle
Macroglossia
Prolonged jaundice
Delayed passage of meconium
Brittle hair/skin
Edema
Bradycardia
Decreased reflexes
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22
Q

What causes decreased thyroid function in premature neonates?

A

Low TBG
Limited TSH surge
Premature withdrawal from maternal contribution
Can resolve after six weeks of age

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23
Q

What hormones in sick preemies can inhibit and reduce TSH secretion?

A

Dopamine

Glucocorticoids

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24
Q

What can methimazole cause in infants?

A

Cutis aplasia

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25
Are infants of mothers with maternal Graves’ disease hypo or hyperthyroid?
Can be either | Thyroid receptor blocking antibodies and thyroid stimulating antibodies both cross the placenta
26
Treatment for hyperthyroidism
The order matters 1. Methimazole 2. Iodide (stuns thyroid, saturates receptors) 3. Beta blocker (Controls HR)
27
What forms the anterior pituitary?
Evagination of oropharynx | Rathkes pouch
28
What forms the posterior pituitary?
Evagination of the floor of the third ventricle
29
When does the hypothalamic-pituitary axis mature?
20 weeks of gestation
30
Importance of testosterone from testes
Needed to allow for penile length
31
What is increased in 3beta HSD?
Pregnenolone 17-OH pregnenolone DHEA
32
Symptoms of 3beta HSD
``` Salt wasting (no aldosterone) Cortisol deficiency Undervirilized male, virilized female ``` Newborn screen won’t catch this
33
Symptoms of 17beta HSD
Undervirilized male Sufficient aldosterone and cortisol Increased androstenedione
34
Symptoms of 5alpha reductase deficiency
Undervirilized male | Testes at 12 - enough testosterone with puberty to -> external genitalia development
35
Micropenis with decreased GnRH
GnRH receptor mutation
36
Micropenis with increased GnRH
LH receptor mutation
37
Symptoms of 21 hydroxylase deficiency
Salt wasting Cortisol deficiency Virilized female
38
Elevated 17 OHP
21 hydroxylase deficiency
39
Genetics of 21 hydroxylase deficiency
Autosomal recessive | CYP21A2 gene
40
Symptoms of 11 hydroxylase deficiency
Elevated deoxycorticosterone -> hypertension | Overvirilized female
41
How does maternal calcium adapt during pregnancy?
Increase calcium from gut and skeleton | Decreased calcium in urine
42
How much of total calcium is accumulated during the third trimester?
80%
43
When do phosphorus and magnesium accretion peak during pregnancy?
Third trimester | Ca > Phos > Mag
44
Mineral accretion is directly correlated to ___
Fetal weight gain
45
What are the actions of parathyroid hormone?
Increase Ca gut resorption Decreased calcium in the urine Increased calcium in the bone
46
What hormone does vitamin D need?
PTH
47
What role does PTH play in vitamin D metabolism?
25-OH -> 1,25-OH vitamin D
48
When does the fetal kidney have full capacity for vitamin D hydroxylation?
24 weeks gestation
49
What happens if maternal vitamin D levels are low?
Congenital rickets | No vitamin D to cross the placenta
50
What are the effects of estrogen on bone metabolism?
Increased mineral accretion in bone
51
What is the effect of GH on bone metabolism?
Proliferation of chondrocytes
52
What is the effect of PTHrP on bone metabolism?
Differentiation and proliferation of resting chondrocytes
53
What is the effect of vitamin A on bone metabolism?
Deficiency inhibits longitudinal bone growth
54
What is the effect of elevated calcitonin on bone metabolism?
Inhibition of bone resorption | Worse for bones
55
Umbilical Cord versus maternal calcium levels
Cord calcium levels are 1-2 mg/dL higher than maternal concentration
56
Neonatal compensation after birth for calcium
Increase PTH Increase efficiency of intestinal Ca absorption (without vitamin D) - 1 month only Renal maintenance of Ca and Phos homeostasis
57
Why do IDM babies have hypocalcemia?
Decreased transplacental transfer of calcium | 2/2 increased urinary excretion of Ca and Mg (maternal glycosuria)
58
Which mineral is needed for PTH release?
Magnesium
59
Why do blood transfusions lead to hypocalcemia?
Transfused blood contains citrate which sequesters calcium
60
Why do glucocorticoids lead to hypocalcemia?
Transient suppression of bone turnover - Decreased osteoblast proliferation/activity
61
What mineral in TPN reduces vitamin D conversion in the kidneys?
Aluminum | Leads to decreased PTH secretion
62
Which medications can decrease calcium levels?
Caffeine Loop diuretics Glucocorticoids
63
What is the primary nutritional cause of developing osteopenia of prematurity?
Phosphorus deficiency
64
All enzymatic processes using phosphorus as an energy source require ___ for activation
Magnesium
65
Familial hypocalciuric hypercalcemia
Inactivation of calcium sensing receptor in kidney | PTH is elevated
66
What is the principal metabolic fuel for the brain?
Glucose
67
Where does a fetus get its glucose from?
Maternal glucose thru placental transfer via GLUT1 receptor | There is no fetal endogenous production of glucose
68
What happens at birth once the neonates glucose transfusion is disrupted?
3-5X increase in glucagon Increased epinephrine Increased growth hormone Decreased insulin
69
What are some adaptive mechanisms during a fast/hypoglycemia?
Glycogenolysis Lipolysis Gluconeogenesis Ketogenesis
70
What are the four neonatal sources of glucose?
Dietary Glycogen stores from liver Cleavage of complex sugars from the gut Gluconeogenesis
71
Definition of neonatal hypoglycemia
<50 first 48 hours | <60 After 48 hours
72
Causes of transient neonatal hypoglycemia
Immature adaptation | Hyperinsulinism
73
Causes of prolonged neonatal hypoglycemia
Hyperinsulinism due to: IUGR, prematurity Birth asphyxia Maternal toxemia/preeclampsia
74
Causes of persistent neonatal hypoglycemia
Hormonal- Hyperinsulinism, deficiency of cortisol or GH Glycogenolysis disorders Gluconeogenesis disorders Fatty acid oxidation disorders
75
During hyoglycemia what should the insulin level be?
Undetectable
76
Congenital hyperinsulinism
Due to a focal lesion or entire pancreas secreting insulin | CT and PET scan with 18 fluro L dopa scan can differentiate between the two
77
Congenital disorders of glycosylation
Carbohydrate deficient glycoprotein syndrome | Cannot make N-linked oligosaccharides
78
Symptoms of Congenital disorders of glycosylation
``` Hypoglycemia Developmental delay FTT Hypotonia Coagulopathy Acquired hypothyroidism Seizures ```
79
Most common cause of neonatal hyperglycemia
Iatrogenic
80
Transient Diabetes in neonates
First 4-6 weeks of life Mutation on chromosome 6 Self resolves between 3-6 months of age Large insulin requirements
81
Permanent causes of neonatal hyperglycemia
Pancreatic agenesis Mutations in glucokinase Mutations in sulfonylurea receptor Wolcott-Rallison syndrome
82
Wolcott-Rallison syndrome
Cause of neonatal hyperglycemia Cardiac/hepatic/renal anomalies Multiple epiphyseal/spondyloepiphyseal dysplasia
83
Symptoms of Neonatal diabetes mellitus
``` First 6 months of life IUGR Dehydrated Poor weight gain Hyperglycemia ```
84
Genetic defect in neonatal diabetes mellitus
KCNJ11 or ABCC8 | Activating mutations in K-ATP channels in pancreas
85
Genetics of DEND syndrome
KCNJ11 mutation Chr 11p15.1 Only 20% of patients with this mutation develop DEND syndrome All will have diabetes mellitus
86
Symptoms of DEND syndrome
Developmental delay Epilepsy Neonatal diabetes 
87
Thyroid surge in SGA versus AGA neonates
TSH higher and T4 lower in SGA neonates compared to AGA
88
Thyroglobulin is ___ in preterm infants compared to term infants
Elevated

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