Endocrinology Flashcards
(91 cards)
1
Q
when does anatomic development begin in thyroid
A
3 wk
2
Q
what dermal layer does thyroid arise from?
A
median endodermal thickening in the primitive pharyngeal floor at 5-7 weeks
3
Q
when does trh production begin?
A
6-8 weeks
4
Q
when does thyroid follicles form?
A
8 weeks
5
Q
when does thyroglobulin production begin?
A
8 weeks
6
Q
when does iodide accumulate in fetal thyroid?
A
10 weeks
7
Q
when does pituitary make tsh?
A
12 weeks
8
Q
when are thyroid hormones secreted from thyroid gland?
A
12 weeks
9
Q
T4 levels pattern pre and post delivery
A
- low until 18-20 weeks
- then increase with GA
- increase with TSH surge at birth
- peak at 24-36 hours then decrease over 1-2 weeks
10
Q
T3 levels pattern pre and post delivery
A
- low until 30 weeks when able to convert T4 to T3 with deiodination
- increase dramatically at birth
- peak at 24-36 hours then continue to increase over 1-2 weeks
11
Q
TSH levels pattern pre and post delivery
A
- low until 18-20 weeks
- increase proportional to GA
- surge at birth
- peak at 30 minutes, decrease over 1-2 weeks
12
Q
which cross placenta?
TRH
T3
T4
Iodide
TSH
TSH Abs
A
TRH - yes
T3 - partial
T4 - partial
Iodide - yea
TSH - NO
TSH Abs - yes
13
Q
what placental hormones affect thyroid hormones?
A
- estrogen increase TBG, T4, T3
- hCG increase T4 and T3
14
Q
which is secreted more from thyroid? T3 or T4
A
T4
15
Q
which is more potent? T3 or T4
A
T3
16
Q
which has higher blood concentration? T3 or T4
A
T4
17
Q
which has higher protein binding affinity? T3 or T4
A
T4
18
Q
which is present more in free form? T3 or T4
A
T3
19
Q
which has higher plasma half life? T3 or T4
A
T4
20
Q
where is T3 localized?
A
intracellular
21
Q
where is T4 localized?
A
extracellular
22
Q
what does T3 resin uptake measure?
A
- amount of unsaturated binding sites on TBG
- radioactive T3 binds to sites; the rest bind to resin which is measured
- higher resin binding means less open sites
23
Q
Free T4 index?
A
T4 X (T3 resin uptake/T3 resin uptake control)
corrects for TBG concentration
24
Q
Pendred syndrome
A
- AR
- organification defect with congenital 8th nerve abnormality
- deafness
- goiter
- positive percholate discharge test
- rapid loss of radioactive iodine from thyroid gland
25
low T4 and high TSH
thyroid dysgenesis
dyshormonogenesis
transient primary hypothyroidism
26
low free T4 normal TSH
transient hypothyroxinemia of prematurity
sick euthyroid syndrome
thyroglobulin deficiency
congenital TSH deficiency
27
normal free T4 and high TSH
transient hypothyroidism
thyroid dysgenesis
28
best way to give levothyroxine
crushed tablets directly - may cling to syringe
small amounts into milk and then mouth
not absorbed well in soy
29
types of TRAbs
thyroid receptor stimulating antibodies (TSIs) and thyroid receptor blocking antibodies (TBAs)
30
maternal treatment options for graves
ptu: during first trimester
methimazole after first trimester
31
side effects of ptu
- preauricular sinus/fistula
- GU anomalies
- LBW
32
side effects of methimazole
- cutis aplasia
- choanal atresia
- GI defects
33
timing of sending levels on infant with exposure to TRAbs
3-5 days
10-14 days;
4 weeks
2-3 months
34
how does methimazole work?
inhibit thyroid peroxidase - decreasing TH synthesis
35
how does ptu work?
inhibits thyroid peroxidase and blocks peripheral conversion of T4 to T3
36
effect of beta blockers on thyroid hormones
inhibits peripheral conversion of t4 to t3
37
effect of potassium iodide (lugols soln) on thyroid hormones
inhibits thyroid hormone release and synthesis
38
effect of glucocorticoids on thyroid hormones
- decrease th secretion
- block peripheral conversion of t4 to t3
39
what is adrenal cortex derived from?
mesoderm
40
what is adrenal medulla derived from
neuroectodermal cells of neural crest
41
when does the gonadal ridge give rise to the steroidogenic gonadal cells and adrenal cortex cells?
5-6 weeks before migrating caudally (gonadal cells) and retroperitoneally (adrenal)
42
when do the sympathetic neural cells invade the adrenal cells to form the adrenal medulla
7-8 weeks
43
when does the adrenal gland become encapsulated?
8 weeks
44
MCC of CAH
21 hydroxylase deficiency
45
pathophysiology of 21 hydroxylase deficiency
can not convert progesterone to deoxycortisone --> aldosterone deficiency (salt wasting)
cannot convert 17-OH progesterone to 11 deoxycortisol --> cortisol deficiency
increased 17OHP and increased testosterone
46
how does 21 hydroxylase deficiency affect XX and XY
XX- ambigious genitalia
XY - normal
47
electrolyte abnormalities in 21 hydroxylase deficiency
hyponatremia
hyperkalemia
hypoglycemia
48
pathophys of 11 beta hydroxylase deficiency
- deoxycorticosterone acts as mineralocorticoid so no salt wasting
- cannot convert 11 deoxycortisol to cortisol --> cortisol deficiency
- increased 11 deoxycortisol --> increased testosterone
49
2nd MCM of CAH
11 beta hydroxylase deficiency
50
how does 11 beta hydroxylase deficiency effect XX and XY?
XX - ambiguous
XY - normal
51
how does 17 alpha hydroxylase deficiency effect XX and XY?
XX - normal
XY - ambiguous
52
how does 3 beta hydroxysteroid dehydrogenase deficiency effect XX and XY?
xx- ambiguous
xy - ambigious
53
pathophysiology of 17 alpha hydroxylase deficiency
- blocks DHEA to androstenediol conversion
- elevated DOC and corticosterone
- low 17 OHP and low 17 OH pregnenolone
54
pathophys of 3 beta hydroxysteroid dehydrogenase deficiency
elevated 17 OH, pregnenolone, DHEA
55
pathophysiology of aromatase deficiency
- inability to convert testosterone to estradiol and androstenedione to estrone
- virilized female
56
pathophysiology of 5a reductase deficiency
AR
inability to convert testosterone to dihydrotestosterone
undervirilized XY
normal XX
57
what hormones released from Leydig and Sertoli cells?
Leydig
- INSL3 - testicular development
- testosterone
>> wolfian duct development
>> external 2/2 DHT
Sertoli
- MIS/AMH: regression of mullerian duct
58
micropenis is due to hormonal abnormality after what week GA?
14; decreased testosterone
59
what is hydrometrocolpos?
- collection of fluid in fetal uterus and vagina 2/2 vaginal blockage (imperforate hymen/high vaginal septum/vaginal atresia/urogenital sinus) and excess vaginal fluid
may require drainage as it can lead to obstruction of other organs
60
how does diazoxide work?
suppress insulin release
61
What is pituitary gland derived from
ectodermal tissue
62
what is neurohypophysis derived from?
floor of forebrain
63
what is adenohypophysis derived from
primitive oropharynx; Rathkes pouch
64
when does HPA axis develop
18-20 weeks
65
what hormones come from anterior lobe
tsh LH FSH prolactin GH ACTH and pro-opiomelaocortin
66
what hormones come from posterior lobe
vasopressin and oxytocin
67
when are hypothalamic hormones detected
8-12 weeks
68
placental transfer of Ca, Phos and Mag
active
69
postnatal Ca levels
- rise first 6 hours
- lowest at 24-48 hours
70
postnatal PTH
increases after birth peaking at 48 hours
71
postnatal calcitriol
- increases after birth
- constant after 24 hours
72
postnatal phosphate levels
high first few days then declines
73
postnatal calcitonin levels
increases after birth then decreases slowly
74
Ca regulation intestines, kidney, bone
- 20-60% reabsorbed in intestines (proximal SI)
- filters free in kidney, 98% reabsorbed (60% PT, 35% loop)
- released from bone 2/2 cortisol and thyroid hormone
75
Phos regulation intestines, kidney, bone
- 70-90% absorption in intestines
- filters free P, 90% reabsorbed esp PT
- released from bone 2/2 cortisol and thyroid hormone
76
PTH action intestines, kidney, bone
- Intestines:
-- indirectly increases Ca, Phos absorption via vit D
- Kidney:
-- increases Ca (ascending loop), decreases P and HCO3 reabsorption (increase Cl)
-- increases renal calcitriol
- Bone:
-- increases Ca and Phos release from bone with vit D
77
Vit D action intestines, kidney, bone
- increases Ca and slightly P in intestines (1,25)
- converted to 1,25 in kidney
- increase effect of PTH on bone
78
Calcitonin action intestines, kidney, bone
- no effect on intestines
- small increase in Ca, P excretion
- inhibits release of Ca and P from bone
79
differences between metabolic bone disease, osteopenia, osteomalacia and rickets
_metabolic bone disease_ - decreased bone **mineral content**
_osteopenia_ - decreased **osteoid**, matrix mineralized
_osteomalacia_ - **poorly mineralized** osteoid and bone
_rickets_ - inadequate mineralization of **growth plates**
80
lab findings of metabolic bone disease
- normal Ca (normal PTH)
- low phos
- elevated alk phos
- 25 vit D normal
- 1,25 vit D elevated
- normal/elevated PTH
81
increased Ca, decreased P
primary hyperPTH
82
decreased Ca, increased P, low PTH
primary hypoparathyroid
83
decreased Ca, increased P, high PTH
primary pseudohypoparathyroid - PTH resistance
chronic renal failure
84
MCC congenital cardiac defect in IDM
TGA
85
what hormones contribute to macrosomia in IDM
IGFBP3 and IGF1
86
effect of dopamine on thyroid pathway
inhibit secretion of TSH
87
effect of caffeine on thyroid pathyway
inhibit secretion of TSH
88
postnatal TSH surge in SGA vs AGA
higher TSH surge
lower T4
89
incidence of thyroid disease in infant born to woman with Graves
1-5%
90
which has more FT or PT?
thyroglobulin
iodide stores
TBG
thyroglobulin - PT
iodide stores - FT
TBG - FT
91
critical period of external virilization
6-12 weeks
