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endo Flashcards

1
Q

what does the SRY gene expression do?

A

If expressed, it causes testicular development. If not, ovarian development.

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2
Q

What dose AMH come from and what is its function?

A

Sertoli cells secrete Anti Mullerian Hormone (also responsible for spermatogenesis). If secreted, mullerian ducts degenerate. If absent, mullerian ducts persist

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3
Q

What causes wolffian ducts to persist?

A

Testosterone secretion by Leydig cells induce wolffian ducts to differentiate into epididymis, vas deferens, seminal vesicle. If AMH present, mullerian ducts degenerate.

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4
Q

What do mullerian ducts differentiate into?

A

fallopian tubes, uterus, cervix, upper vagina

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5
Q

When do testes descend into scrotum?

A

28-36 weeks

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6
Q

Which cells produce testosterone?

A

Leydig cells (pneumonic, Tay Diggs has a lot of testosterone)

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7
Q

What happens in 5a-reductase deficiency?

A

46 XY DSD
low/absent conversion of testosterone to DHT.
internal male structures
At puberty will have virilization bc of testosterone burst.

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8
Q

What is the etiology of androgen insensitivity?

A

46 XY DSD
Complete or partial dysfunction of androgen receptor, so can produce all the hormones but not responsive to testosterne/DHT.
PAIS: ambigous genitalia in male
Presents as primary amennorhea in phenotypic female, or with inguinal hernia with testicle in it

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9
Q

What DSD does CAH cause?

A

46 XX DSD –> virilization due to increased testosterone production. Would not have gonads.

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10
Q

What can micropenis be associated with?

A
  • abnormal hypo/pit function (deficient LH, GH)
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11
Q

how can hypospadias/epispadias be treated?

A
  • avoid circ

- surgery at 6m - 1y

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12
Q

how can micropenis be treated?

A
  • GH

- short course of testosterone (q3-4w, for 3-4m)

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13
Q

When and how do you treat cryptorchidism?

A

Unlikely to descent after 4 m CGA. Orchiepexy 6-15m.

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14
Q

what does maternal new onset hirsutism indicate?

A

Indicates the possibility of placental aromatase deficiency resulting in accumulation of excess androgens in maternal fetal circulation. Can result in virlization of XX female.

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15
Q

What are normal testosterone surges in childhood?

A

Testosterone production is present at birth, rapidly declines and then surges at ~1m (mini puberty of infancy). It peaks at 2-3m. Then almost non-detectable at 6m.Rises again at puberty 9-14y/o.

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16
Q

What components is the adrenal gland made of?

A

Adrenal cortex (from outside inward, mesoderm):
Zone glomerulosa: for mineralocorticoid (aldosterone)
Zone fasciculata: glucocorticoid (cortisol)
Zone reticularis: androgens (DHEA and androstendione)

Adrenal medulla (inner most component, neuroectoderm): Catecholamines (epinephrine)

Transient fetal adrenal zone (cortex)- This is where fetal adrenal steroid hormone production occurs. It involutes after birth and is absent by 6-12m.

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17
Q

How does steroid synthesis progress in fetus?

A

Maternal cholesterol is converted to steroid hormone precursors via placental enzymes (aromatase and 3B HSD). Fetus receives the precursors and converts to androgens in adrenals.

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18
Q

What are the proteins required for cholesterol transport into mitorchondria?

A

StAR: steroid acute regulatory protein and

CYP11A1, Cholesterol side chain cleavage enzyme

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19
Q

What is the rate limiting step of steroid synthesis

A

conversion of cholesterol into pregnenolone

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20
Q

Where do the final steps of androgen conversion occur?

A

DHEA and androstenedione are converted into testosterone and estrogen in gonads and some peripheral tissues (not adrenals).

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21
Q

How is Congenital Adrenal Hyperplasia inherited and what is the most common kind.

A

All CAH is autosomal recessive. 95% are due to 21-hydroxylas deficiency (CYP21)

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22
Q

What causes the hyperplasia in CAH?

A

Enzyme deficiency causes decrease cortisol production. This increases ACTH which causes adrenal hyperplasia. Shunts precursors towards increased androgen production and virilization. 75% causes decreased aldosterone production as well with ‘salt wasting’ –> hyperkalemia and hyponatremia.

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23
Q

How do you diagnose CAH?

A

17-OHP after 24h (otherwise can be falsely elevated). >10,000 is assc with CAH. Can confirm with ACTH stim test or CYP21 sequencing. Again 17-OHP after stim should be >10,000.

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24
Q

How do you treat CAH?

A

Cortisol 100mg/m2/day during stress. Otherwise 15mg/m2/day. Na and fludrocortisone if needed.

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25
Q

Which CAH can cause undervirilization of males?

A

17-hydroxylase deficiency (CYP-17)

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26
Q

Which forms of CAH are associated with early onset hypertension?

A

11 B hydroxylase deficiency and 17- hydroxylase deficiency. Both cause elevated levels of 11-deoxycorticosterone which has mineralocorticoid activity.

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27
Q

What are the two types of tissue forming the thyroid gland?

A
  • Follicular cells (thyroid hormone producing cells) derived from endodermal cells. Migrate down from tongue to anterior neck. Thyroglossal duct may persist as cyst.
  • C cells (calcitonin producing cells) derived from neural crest cells, which fuse with rest of thyroid gland 8-10 weeks.
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28
Q

What does thyroidal peroxidase do?

A

Oxidizes iodide in follicular cell so it can bind to tyrosine residues in thyroglobulin

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29
Q

What is the ratio of T4 to T3

A

5:1, but T3 is the more active component. T4 converted to T3. Most T4 and T3 is bound to thyroid binding globulin (TBG).

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30
Q

How does the fetus get thyroid hormone?

A

Fetal thyroid hormone synthesis begins 12-14w. Until then maternal T4 crosses placenta. T3 and TSH does not cross placenta.

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31
Q

What is the natural course of TSH after birth?

A

TSH surge due to cold exposure, which peaks at 30 minute and elevated w/i 24 hours. Therefore risk of false positive TSH if in first 24 hours. T4 peaks DOL 2.

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32
Q

what are the primary causes of hypothyroidism?

A

dysgenesis and dyshormonogenesis

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33
Q

what causes neonatal hyperthyroidism

A

1 cause is Maternal graves, with TSH receptor stimulating (or blocking) Ab crosss placenta –> cause thyrotoxicosis in neonate. Check TSH/T4 levels at 3-5 days. Self resolves in 3-5 months. Can happen even if mother has been treated for Graves because Ab persist. Graves can also cause hypothyroidism. Dx: check maternal TRAb levels at 28 weeks, and then in cord if it was (+).

Also McCune Albright.
symptomatic around 10d on average. may inititally be euthyroid b/c of maternal meds.
IUFD may happen secondary to cardiac failure and hydrops. Otherwise, IUGR, tachycardic, accelerated bone maturation.
Longterm effects include craniosynostosis.

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34
Q

How do you treat neonatal hyperthyroidism?

A

Proponalol, methimazole/PTU (anti-thyroid meds), iodine, glucocorticoids. Usually resolves in 3-6 months.
SIMBa down - steroids, iodine, MTZ, B-blocker

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35
Q

What is the association with thyroid hormone and hepatic hemangioma?

A

Can be associated with a consumptive hypothyroidism due to overexpression of deonidase 3 which causes reversal of T3.

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36
Q

Describe TBG deficiency

A

Inherited due to SERPINA7A, X-linked. Does not need to be treated with levothyroxine. Free thyroid levels are normal.

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37
Q

Define hypothermia

A

Mild: 36-36.5
Moderate: 32-36
Severe: less than 32 degrees C

38
Q

Describe the kinds of heat loss

A

Conductive: transfer from contact
Convective: Transfer from air current
Evaporative: transfer from object through moisture in air (markedly increased in preterm)
Radiant: transfer from object with heat radiating towards cooler surface (most common in term/later pt)

39
Q

What is the primary mediator of physiologic response to cold stress?

A

Norepinephrine. Causes vasoconstriction which decreases conductive and convective heat loss, and stimulates brown adipose tissue.

40
Q

What are counter-regulatory hormones in response to hypoglycemia?

A

Glucagon, cortisol/GH, epinephrine. Catecholamines inhibit insulin reason and sensitivity of tissues to insulin.

41
Q

how does diazoxide work

A

Used in hyperinsulinism, suppresses insulin release by opening K atp channel. Consider diuretics because it can cause fluid retention. Monitor CBCs for cytopenia.

42
Q

How does glycogen storage disease present

A

GSD-1 is glucose 6 phosphatase deficiency. Presents with severe lactic acidosis and hepatomegaly when glycogenolysis and therefore gluconeogenesis is blocked during fasting.

43
Q

What sources of energy can the brain use?

A

Glucose is the main, via glut-3 transporter. Ketones and LA can be used. Fatty acids cannot cross the BBB.

44
Q

What is the difference between fetal PTH and PTH-related protein?

A

PTH: secreted by fetal parathyroid gland, maintains high fetal ca levels, promotes bone formation.
PTH-rP: secreted by placenta, regulates ca transport across placenta, maintains high fetal ca levels, regulates ossification centers
PTH surge after birth b/c of loss of PTH-rP from placenta

45
Q

What is the relationship between PTH and magnesium?

A

Normal Mg needed for PTH secretion.

46
Q

What are the actions of PTH?

A

On renal tubules: increase Calcium absorption, decrease phosphorous absorption. Increases Vit D production in kidney.
On bone: increase calcium and phos resorption
On GI tract: increase calcium and phos absorption via activation of Vitamin D

47
Q

How is Vit D formed and what actions does it have on Ca and Ph?

A

absorbed in skin –> hydroxylated to 25-OHD in liver –> activated to 1,25-OHD in kidney. 25-OHD is better to use as measurement.

  • Increases GI absorption of Ca and Ph
  • Increases Bone resorption and renal absorption of Ca
48
Q

what does calcitonin do?

A

Secreted by C cells in thyroid gland, decreases calcium by decreasing bone break down via osteoclastic activity.

49
Q

What is the ideal Vit D, Ca and Ph intake?

A

Ca: 150-200 mg/kg/day
Ph 75-140 mg/kg/day
Vit D 200-400 IU/d
Ca: Ph ratio 1.7:1

50
Q

What can cause hypophosphatemic rickets?

A

Elemental formula, treatment can cause hypocalcemia.

51
Q

vitamin d intoxication will cause an elevation in what?

A

Vit D 25-OH

52
Q

How does glucose cross the placenta?

A

Facilitated diffusion

53
Q

Which cross over the placenta and which don’t?

Glucose, insulin, glucagon, FFA, ketones, amino acids

A

Cross over: glucose, ketones, AA
Don’t: insulin, glucagon, FFA
This is why maternal DKA is very bad for fetus.

54
Q

Diseases of bone metabolism:

What is the etiology of Vit D resistant rickets and what are common symptoms and treatment?

A

AR acquired. Receptor for calcitriol (1-25 OH vit D) is dysfunctional so it cannot act on gut and bone to increase calcium and phos. Tx with calcium and phos. Associated with familial alopecia.

55
Q

Diseases of bone metabolism:

What is the etiology of X linked hypophosphatemic rickets and what are common symptoms and treatment?

A

Inability of kidney to reabsorb phos. Also may have impaired 1-a-hydroxylase (necessary enzyme in kidney to convert 25OH to 1-25 OH) so calcitriol is unavailable. Patient may benefit from calcitriol treatment and Phos. Presents with delayed dentition and tooth abscesses.

56
Q

Diseases of bone metabolism:

What is the etiology of Pseudo-Vitamin D deficiency rickets and what are common symptoms and treatment?

A

Action of 1-a-hydroxylase is impaired so kidney cannot make 25-OH to 1-25 OH. Need to treat with calcitriol. AR

57
Q

Diseases of bone metabolism:

What is the etiology of hypophosphatasia and what are common symptoms and treatment?

A

Abnormality in alk phos - poor bone mineralization

58
Q

what are typical lab values in hyperinsulinism

A

insulin may be low or normal. cortisol and GH will be elevated during fasting. FFA and b-hydroxybutarate (serum ketones) will be low. test with glucagon - if rise >30, indicates glucose was around but insulin is suppressing it

59
Q

when does CAH present?

A

between 1-4 weeks

60
Q

what is thyroglobulin?

A

thyroglobulin is the storage form of thyroxine. It is elevated in PT and sick infants.

61
Q

what is incretin?

A

incretin is stimulated by food, it stimulates insulin to decrease glucose (like a little insulin creature)

62
Q

how does adrenal hemmorhage present?

A

usually mild-moderate: jaundice, discoloration of skin and anemia.
usually unilateral and R sided
if severe, can present with shock, adrenal insufficiency and as scrotal hematoma from leakage of blood if capsule is ruptured
usually only requires supportive therapy and self resolves

63
Q

what is the adverse effect of PTU

A

liver failure

64
Q

what is the adverse effect of Methimazole

A

cutis aplasia, esophageal atresia/tef, choanal atresia

65
Q

what does 5a reductase do?

A

converts testosterone to DHT. if deficient, ambiguous genitalia in males b/c DHT is primary hormone responsible for external genitalia

66
Q

what does DHT do?

A

In first trimester, causes fusion of labia and formation of scrotum and penis. In 2nd trimester causes phallic enlargement and testicular descent.

67
Q

what stimulates testosterone in first and second trimesters?

A

first: placenta hcg –> leydig cells –> testosterone
2nd: pituitary –> fetal LH –> testosterone

68
Q

in which CAH do you have elevated DOC (deoxycorticosterone)

A

in 11 b hydroxylase deficiency

69
Q

what is most common thyroid hormone in fetus vs neonate?

A

fetus - rT3, neonate - T4

70
Q

what is calcitriol vs ergocalciferol

A

calcitriol: 1, 25, OH (all the 1 looking letters)
ergocalciferol: 25, OH (okay to give if ptH is okay for hypocalcemia)

71
Q

What does ca, calcitonin, ph, and path do right after birth?

A

Calcium is accumulated most in third trimester. After birth, Ca goes down to stimulate PTH. Calcitonin goes up. Calcitriol and ph increase.

72
Q

What and when is normal thyroid embryogenesis?

A

3w: gland descends from base of tongue to neck
8w: thyroid follicles form and start thyroglobulin production.
10w: iodine accretion (IO ; 10)
12w: tsh and thyroid hormone production
20w: TSH receptors become responsive to TSH and TSH receptor Ab

73
Q

What are the hormones, and when, that are responsible solve for phallic development?

A

1st trimester: maternal HCg stimulates neonatal adrenal glands to synthesize testosterone
2/3rd trimester: LH stimulates leydig cells to synthesize testosterone. In 12th week testosterone starts to convert to DHT

FSH stimulates Sertoli cells for spermatogenesis (S —> s)

74
Q

How do androgen insensitivity and 5a redux tase present different clinically?

A

Both are 46 XY

AIS: failure of wolffian duct - female externally, may have blind vaginal pouch, have testes, many have inguinal hernia

5aR: reduces male parts: ie small penis

75
Q

what does mono-deionidase do?

A

abundant in placenta

removes iodine from t4 to rt3 and t3. MDI3 goes to rT3, MDI1 and 2 to t3 (needed for brain)

76
Q

how is thyroid hormone different after birth in PT vs T?

A

PT have less TSH surge, and less T4, and lower nadir at week 1

77
Q

how does hyperthyroidism present?

A

can have craniosynostosis, eye findings

78
Q

how will sepsis impact thyroid hormones?

A

frequently these patients will have sick euthyroid (low T3), with low-ish t4 but normal tsh. Do not treat with synthroid

  • in sick euthyroid, you have decreased TBG binding (may cause slight increase Ft4)
  • abnormal deoinidization (inhibition of 5’ deionidation which normally converts t4 –> t3), increase in rT3
79
Q

how long do you treate hypothyroidism for?

A

treat for 3 years, take a break for a month and see how levels are impacted

80
Q

when is macrosomia (>4k//90%) notable during pregnancy?

A

starting at 20 weeks when fat begins to deposit in abdomen and scapular area. no difference in size in 1st trimester.

81
Q

what is the role of placental hcg?

A

progesterone
into M circulation –> peaks at 8w and stimulates progesterone from corpus luteum, by 13w placenta takes over progesterone (2nd trimester when placenta is complete)

82
Q

what is the role of placental HGHv (human growth hormone variant)?

A

growth from M

into M circulation –> maternal GH suppressed, HGH stimulates IGF

83
Q

what is the role of placental HPL (human placental lactogen)?

A

growth from M and F
aka hcs (human chorionic somatomammotropin)
in M –> stimulates IGF, fetal growth regulation
in F –> stimulates IGF and insluin, embryonic development

84
Q

what is the role of placental IGF?

A

increases glucose and AA available for F

85
Q

what is the role of placental CRH?

A

in F –> increases cortisol and lung maturation. peaks at labor, may be involved in onset of labor

86
Q

what is the role of placental steroid hormones estrogen and progestrone?

A

estrogen: secreted throughout pregnancy, regulates progesterone, maturation of F organs, stimualtion of F ACTH, proliferation of endometrium
progesterone: maintains quiescent uterus, protects fetus from ummune rejection, suppress lactation

87
Q

what are criteria for looking for DSD?

A
  • any degree of hypospadias + any degree of cyrptorchidism
  • cliteromegaly
  • b/l impalpable gonads
88
Q

what is ovotesticular DSD?

A

XX > XY/XX > XY
a mixed gonad with both ovarian and testicular tissue
dx: biopsy
tx: remove discordant gonadal tissue

89
Q

what is mixed gonadal dysgenesis DSD?

A

45 XO/45 XY
one side has streak gonad (dysgenetic ovary with mullerian structures on ipsilateral side) and other side has abnormal teste
tx: remove streak gonad due to tumor risk

90
Q

which CAH causes hypertension?

A

17 a b/c everything is shunted to aldosterone. Think teenager –> hypertension

91
Q

what is the MOA of pty/meth?

A

inhibit thyroid hormongenesis by interfering with thyroid peroxidase

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