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endo Flashcards

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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
Which CAH can cause undervirilization of males?
17-hydroxylase deficiency (CYP-17)
26
Which forms of CAH are associated with early onset hypertension?
11 B hydroxylase deficiency and 17- hydroxylase deficiency. Both cause elevated levels of 11-deoxycorticosterone which has mineralocorticoid activity.
27
What are the two types of tissue forming the thyroid gland?
- 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.
28
What does thyroidal peroxidase do?
Oxidizes iodide in follicular cell so it can bind to tyrosine residues in thyroglobulin
29
What is the ratio of T4 to T3
5:1, but T3 is the more active component. T4 converted to T3. Most T4 and T3 is bound to thyroid binding globulin (TBG).
30
How does the fetus get thyroid hormone?
Fetal thyroid hormone synthesis begins 12-14w. Until then maternal T4 crosses placenta. T3 and TSH does not cross placenta.
31
What is the natural course of TSH after birth?
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.
32
what are the primary causes of hypothyroidism?
dysgenesis and dyshormonogenesis
33
what causes neonatal hyperthyroidism
#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.
34
How do you treat neonatal hyperthyroidism?
Proponalol, methimazole/PTU (anti-thyroid meds), iodine, glucocorticoids. Usually resolves in 3-6 months. SIMBa down - steroids, iodine, MTZ, B-blocker
35
What is the association with thyroid hormone and hepatic hemangioma?
Can be associated with a consumptive hypothyroidism due to overexpression of deonidase 3 which causes reversal of T3.
36
Describe TBG deficiency
Inherited due to SERPINA7A, X-linked. Does not need to be treated with levothyroxine. Free thyroid levels are normal.
37
Define hypothermia
Mild: 36-36.5 Moderate: 32-36 Severe: less than 32 degrees C
38
Describe the kinds of heat loss
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
What is the primary mediator of physiologic response to cold stress?
Norepinephrine. Causes vasoconstriction which decreases conductive and convective heat loss, and stimulates brown adipose tissue.
40
What are counter-regulatory hormones in response to hypoglycemia?
Glucagon, cortisol/GH, epinephrine. Catecholamines inhibit insulin reason and sensitivity of tissues to insulin.
41
how does diazoxide work
Used in hyperinsulinism, suppresses insulin release by opening K atp channel. Consider diuretics because it can cause fluid retention. Monitor CBCs for cytopenia.
42
How does glycogen storage disease present
GSD-1 is glucose 6 phosphatase deficiency. Presents with severe lactic acidosis and hepatomegaly when glycogenolysis and therefore gluconeogenesis is blocked during fasting.
43
What sources of energy can the brain use?
Glucose is the main, via glut-3 transporter. Ketones and LA can be used. Fatty acids cannot cross the BBB.
44
What is the difference between fetal PTH and PTH-related protein?
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
What is the relationship between PTH and magnesium?
Normal Mg needed for PTH secretion.
46
What are the actions of PTH?
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
How is Vit D formed and what actions does it have on Ca and Ph?
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
what does calcitonin do?
Secreted by C cells in thyroid gland, decreases calcium by decreasing bone break down via osteoclastic activity.
49
What is the ideal Vit D, Ca and Ph intake?
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
What can cause hypophosphatemic rickets?
Elemental formula, treatment can cause hypocalcemia.
51
vitamin d intoxication will cause an elevation in what?
Vit D 25-OH
52
How does glucose cross the placenta?
Facilitated diffusion
53
Which cross over the placenta and which don't? | Glucose, insulin, glucagon, FFA, ketones, amino acids
Cross over: glucose, ketones, AA Don't: insulin, glucagon, FFA This is why maternal DKA is very bad for fetus.
54
Diseases of bone metabolism: | What is the etiology of Vit D resistant rickets and what are common symptoms and treatment?
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
Diseases of bone metabolism: | What is the etiology of X linked hypophosphatemic rickets and what are common symptoms and treatment?
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
Diseases of bone metabolism: | What is the etiology of Pseudo-Vitamin D deficiency rickets and what are common symptoms and treatment?
Action of 1-a-hydroxylase is impaired so kidney cannot make 25-OH to 1-25 OH. Need to treat with calcitriol. AR
57
Diseases of bone metabolism: | What is the etiology of hypophosphatasia and what are common symptoms and treatment?
Abnormality in alk phos - poor bone mineralization
58
what are typical lab values in hyperinsulinism
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
when does CAH present?
between 1-4 weeks
60
what is thyroglobulin?
thyroglobulin is the storage form of thyroxine. It is elevated in PT and sick infants.
61
what is incretin?
incretin is stimulated by food, it stimulates insulin to decrease glucose (like a little insulin creature)
62
how does adrenal hemmorhage present?
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
what is the adverse effect of PTU
liver failure
64
what is the adverse effect of Methimazole
cutis aplasia, esophageal atresia/tef, choanal atresia
65
what does 5a reductase do?
converts testosterone to DHT. if deficient, ambiguous genitalia in males b/c DHT is primary hormone responsible for external genitalia
66
what does DHT do?
In first trimester, causes fusion of labia and formation of scrotum and penis. In 2nd trimester causes phallic enlargement and testicular descent.
67
what stimulates testosterone in first and second trimesters?
first: placenta hcg --> leydig cells --> testosterone 2nd: pituitary --> fetal LH --> testosterone
68
in which CAH do you have elevated DOC (deoxycorticosterone)
in 11 b hydroxylase deficiency
69
what is most common thyroid hormone in fetus vs neonate?
fetus - rT3, neonate - T4
70
what is calcitriol vs ergocalciferol
calcitriol: 1, 25, OH (all the 1 looking letters) ergocalciferol: 25, OH (okay to give if ptH is okay for hypocalcemia)
71
What does ca, calcitonin, ph, and path do right after birth?
Calcium is accumulated most in third trimester. After birth, Ca goes down to stimulate PTH. Calcitonin goes up. Calcitriol and ph increase.
72
What and when is normal thyroid embryogenesis?
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
What are the hormones, and when, that are responsible solve for phallic development?
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
How do androgen insensitivity and 5a redux tase present different clinically?
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
what does mono-deionidase do?
abundant in placenta | removes iodine from t4 to rt3 and t3. MDI3 goes to rT3, MDI1 and 2 to t3 (needed for brain)
76
how is thyroid hormone different after birth in PT vs T?
PT have less TSH surge, and less T4, and lower nadir at week 1
77
how does hyperthyroidism present?
can have craniosynostosis, eye findings
78
how will sepsis impact thyroid hormones?
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
how long do you treate hypothyroidism for?
treat for 3 years, take a break for a month and see how levels are impacted
80
when is macrosomia (>4k//90%) notable during pregnancy?
starting at 20 weeks when fat begins to deposit in abdomen and scapular area. no difference in size in 1st trimester.
81
what is the role of placental hcg?
*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
what is the role of placental HGHv (human growth hormone variant)?
*growth from M* | into M circulation --> maternal GH suppressed, HGH stimulates IGF
83
what is the role of placental HPL (human placental lactogen)?
*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
what is the role of placental IGF?
increases glucose and AA available for F
85
what is the role of placental CRH?
in F --> increases cortisol and lung maturation. peaks at labor, may be involved in onset of labor
86
what is the role of placental steroid hormones estrogen and progestrone?
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
what are criteria for looking for DSD?
- any degree of hypospadias + any degree of cyrptorchidism - cliteromegaly - b/l impalpable gonads
88
what is ovotesticular DSD?
XX > XY/XX > XY a mixed gonad with both ovarian and testicular tissue dx: biopsy tx: remove discordant gonadal tissue
89
what is mixed gonadal dysgenesis DSD?
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
which CAH causes hypertension?
17 a b/c everything is shunted to aldosterone. Think teenager --> hypertension
91
what is the MOA of pty/meth?
inhibit thyroid hormongenesis by interfering with thyroid peroxidase

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