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Uworld Journal > Endocrine and Biochemistry > Flashcards

Endocrine and Biochemistry Flashcards

1
Q

Mechanism of potassium iodide =

A

Competitively inhibits the uptake of radioactive iodine into follicular cells. Increased iodine also decreases release of T4/T3 due to the Wolff Chaikoff Effect.

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2
Q

Function of smooth ER = (3)

A
  • produces steroids and phospholipids (contains the appropriate enzymes)
  • acts as the sarcoplasmic reticulum for striated muscles
  • detoxification of drugs
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3
Q

What medication can be given to men who are suffering from gynecomastia?

A

SERM - inhibits ER in breast tissue

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4
Q

Hypoketotic hypoglycemia in a young kid after a long period of fasting is most likely a deficiency in _

A

FA beta-oxidation

Most likely it is inhibition of acyl CoA dehydrogenase enzyme.
Will not be able to oxidize FA for energy and cannot produce ketone bodies

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5
Q

Superior thyroid artery and vein travel with _ nerve

A

external branch of the superior laryngeal nerve

-innervates the cricothyroid muscle

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6
Q

Inferior thyroid artery and vein travel with _ nerve

A

recurrent laryngeal nerve

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7
Q

Gene from Albright Hereditary Osteodystrophy is inherited from mother/father

A

mother - due to imprinting of father’s genes
AD

defective Gs alpha subunit in the PTH receptor = pseudohypoparathyroidism - end organ resistance to PTH

presentation:

  • serum= low Ca, high P, high PTH
  • shortened 4th/5th digits
  • short stature
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8
Q

Conn syndrome =

A

Primary adrenal adenoma

increased aldo
decreased renin

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9
Q

Addison’s disease =

A

Primary adrenal insufficiency

decreased aldo
decreased cortisol

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10
Q

Metyrapone stimulation test

A

Blocks the last step of cortisol synthesis (11DOC -> cortisol)

Helps dx adrenal insufficiency

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11
Q

11-beta hydroxylase deficiency findings

female genitalia =

A
  • decreased aldo
  • increased 11-DOC (not salt wasting)
  • increased BP
  • decreased renin
  • increased androstenedione

female genitalia are ambiguous (due to increased androstenedione)

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12
Q

21 hydroxylase deficiency findings

female genitalia =
male genitalia =

A
  • decreased aldo (salt wasting)
  • decreased BP
  • increased renin
  • increased 17-hydroxyprogesterone
  • increased androstenedione

female genitalia are ambiguous (due to increased androstenedione)
male genitalia is normal and they are identified later due to salt wasting

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13
Q

17-alpha hydroxylase deficiency findings

female vs male genitalia

A
  • increased aldo (not salt wasting)
  • increased BP
  • decreased androstenedione

females - born with normal genitalia but will not have secondary sex characteristics
males - born undervirilized or with female external genital (due to decreased androstenedione)

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14
Q

Insulin independent glucose uptake locations (6)

A
  • Brain
  • RBC
  • Intestine
  • Cornea
  • Kidney
  • Liver
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15
Q

MEN 1

A
  • Pituitary adenoma (prolactin or GH)
  • Pancreas endocrine tumor (Zollinger-Ellison (gastrinoma), Insulinoma, VIPoma, Glucagonoma)
  • Parathyroid adenomas

mutation in MEN1 gene - menin tumor suppressor protein

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16
Q

MEN2A

A
  • Parathyroid hyperplasia
  • Thyroid medullary carcinoma (C cell tumor - secrete calcitonin)
  • Pheochromocytoma

mutation in RET gene - receptor tyrosine kinase
affects cells of neural crest origin!

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17
Q

MEN2B

A
  • Thyroid medullary carcinoma (C cell tumor - secretes calcitonin)
  • Pheochromocytoma
  • Muosal neuroma (oral/intestinal ganglioneuromatosis)

mutation in RET gene - receptor tyrosine kinase
associated with marfanoid habitus

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18
Q

Hashimoto thyroiditis associated HLA subtype =

A

HLA-DR5, DR3

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19
Q

Diabetes Mellitus Type 1 associated HLA subtype =

A

HLA-DR4

HLA-DR3

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20
Q

Vitamin _ deficiency -> hemolytic anemia, acanthocytosis, posterior column or spinocerebellar tract demyelination

A

Vitamin E deficiency

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21
Q

Niacin is derived from _ and requires what two cofactors?

A

Derived from tryptophan

Cofactors = B2 (riboflavin), B6 (pyridoxine)

Niacin is B3
Requires B2, B6
(6/2=3)

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22
Q

Elfin facies + intellectual disability with well developed verbal skills + hypercalcemia =

A

Williams Syndrome - microdeletion of long arm Chr 7 (includes elastin gene)

Hypercalcemia is due to increased vitamin D sensitivity

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23
Q

Myotnia + Cataracts + Testicular atrophy + CTG repeat =

A

myotonic dystropy type 1

mutation in the DMPK gene -> abnormal myotonin protein kinase

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24
Q

Cancers associated with Li Fraumeni Syndrome (4)

A
  • Sarcoma
  • Breast
  • Leukemia
  • Adrenal gland
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25
Q

Cross linking of elastin is done by _ enzyme

A

lysyl oxidase with copper cofactor required

this is the same enzyme that crosslinks collagen fibrils

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26
Q

Mutation in ATP7A + brittle, kinky hair + growth retardation =

A

Menke disease

-decreased copper absorption which leads to a decreased collagen and elastin synthesis

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27
Q

Coarse facial features + clouded corneas + limited joint movements + increased plasma lysosomal enzymes + child

A

I cell disease - inhibits N-acetylglycosaminyl-1-phosphotransferase enzyme

Results in the failure of the golgi to add a mannose-6-phosphate to glycoproteins that are supposed to be degraded in the lysosome

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28
Q

Ribosomes: prokaryotic vs eukaryotic

  • 80s
  • 70s
A
  • 80s = 40s+60s -> eukaryotes
  • 70s = 30s+50s -> prokaryotes

eukaryotes - even numbers
prokaryotes - odd numbers

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29
Q

tRNA thymine + pseudouracil + cytosine sequence is used for

A

tRNA-ribosome binding

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30
Q

tRNA dihydrouracil residue is used for

A

tRNA recognition of the correct aminoacyl tRNA synthetase

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31
Q

anti-spliceosome snRNP antibody =

A

anti-Smith antibody = SLE!

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32
Q

Lac operon requires what to function?

A

available lactose

glucose can be low or high but as long as lactose is available, there will be transcription of the lac operon

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33
Q

Histones are rich in what 2 amino acids?

A
  • Lysine

- Arginine

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34
Q

Vomiting + Rice water stools + Garlic breath

A

Arsenic poisoning

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35
Q

Infant with increased serum alanine + lactic acidosis + neurological deficits =

A

Pyruvate Dehydrogenase Complex deficiency

  • X-linked
  • Treatment = ketogenic diet (high fat, low carb, high lysine and leucine)

Lysine and Leucine are ketogenic AA -generates the ketone body precursor to acetyl CoA and therefore does not go through the pyruvate pathway

36
Q

Locations of HMP shunt/Pentose Phosphate Pathway (4)

A
  • lactating mammary gland
  • liver
  • adrenal cortex
  • RBC
37
Q

Essential AA (9)

A 
Met
Val
His
Ile
Phe
Thr
Trp
Leu
Lys
38
Q

Acidic AA (2)

A

Asp

Glu

39
Q

Basic AA (3)

A

Arg
Lys
His (neutral at body pH)

40
Q

underlying pathology for Graves’ proptosis =

A

Inflammation

Steroids help decrease the ophthalmic symptoms

41
Q

Main pathogenesis of T1DM =

A

autoimmune insulinitis - cell mediated destruction of the beta-pancreatic cells

42
Q

NADPH is used in what reactions? (4)

A
  • Reduction of glutathione (prevents oxidative damage)
  • Synthesis of cholesterol
  • Synthesis of FA
  • Synthesis of steroids
43
Q

Physical and mental retardation + megaloblastic anemia + increased orotic acid in urine

What is the treatment?

A

Orotic aciduria

Treatment = uridine supplementation

44
Q

Painful rash on face, groin and perineum involving crusting, coalescing erythematous borders with central bronze induration.
Light microscopy shows superficial necrolysis.

A

Glucagonoma

45
Q

Sympathetic stimulation of pancreatic beta cells =

A

Decreases insulin release due to the alpha-2>beta-2

alpha-2 = decreases insulin release due to Gi
beta-2 = increases insulin release due to Gs
46
Q

Why are non-selective beta blockers dangerous in DM patients?

A

Exacerbates the hypoglycemia and masks the adrenergic symptoms that hypoglycemia can cause

47
Q

Thyroid biopsy - empty appearing nuclei with central clearing + nuclear grooves

A

Papillary thyroid carcinoma

  • empty nuclei = Owl’s eyes
  • also presents with psamomma bodies
48
Q

Thyroid nodule that is invading the capsule and surrounding vasculature

A

Follicular thyroid carcinoma

note: this cannot be diagnosed via fine needle biopsy

49
Q

Thyroid biopsy - lymphocytic infiltrate with well developed germinal centers and eosinophilic metaplasia of the cells surrounding the follicles

A

Hashimoto thyroiditis

eosinophilic metaplasia = Hurthle cells

The follicles are making the antibodies (autoimmune pathogenesis)

  • anti-microsomal Ab
  • anti-thyroglobulin Ab
50
Q

Thyroid biopsy - granulomatous inflammation + follows a flu-like illness + painful + increased ESR

A

Subacute (de Quervain) thyroiditis

51
Q

Young patient with a hard painless thyroid

A

Ridel fibrosing thyroiditis

52
Q

Beriberi is a _ deficiency

A

Thiamine (B1)

Causes peripheral neuropathy (“dry”) or peripheral neuropathy + dilated cardiomyopathy (“wet”)

53
Q

What 5 AA can be synthesized into propionyl CoA?

A
  • Valine
  • Leucine
  • Isoleucine
  • Methionine
  • Threonine
54
Q

What AA is used to make NO?

A

Arginine

55
Q

What 2 AA are used to make urea?

A

Arginine

Aspartate

56
Q

What AA is used to make GABA?

A

Glutamate

57
Q

What 3 things can Tryptophan be made into?

A
  • Serotonin
  • Melatonin
  • Niacin
58
Q

Fetal adrenal cortex releases what steroid?

A

DHEA

59
Q

GH release is stimulated by hyper/hypoglycemia?

A

Hypoglycemia

Glucose inhibits GH release

60
Q

5 yo + exophthalmos + lytic bone lesions at the base of the skull + polyuria + polydipsia

A

Langerhans histiocytosis with Diabetes Insipidus

61
Q

Mutations in follicular thyroid carcinoma? (2)

A
  • RAS oncogene

- PAX8-PPAR gamma fusion gene

62
Q

Tapping on facial nerve leading to contraction occurs in increased/decreased serum Ca?

A

Chvostek sign

  • Indicates decreased serum Ca
  • Usually due to hypoparathyroidism - low PTH, low Ca
63
Q

Locations of ADH receptors

A

V1 - vascular smooth muscle

V2 - cortical collecting duct and vascular endothelium

64
Q

GH is _ in striated muscle and _ in adipose tissue

A
  • anabolic in striated muscle

- catabolic in adipose tissue

65
Q

Maturity onset diabetes of the young/gestational diabetes is caused by a mutation in _ enzyme

A

Glucokinase

66
Q

Underlying cause of DKA?

A

Lack of insulin

67
Q

Renal osteodystrophy occurs with _ hyperparathyroidism

A

Secondary or Tertiary

  • Due to an underlying renal problem -> decreased vitamin D -> decreased Ca from gut -> decreased serum Ca -> increased PTH
  • Renal problem -> increased serum P because it cannot be removed properly
68
Q

Subperiosteal resorption with cystic degeneration + decreased serum phosphate + increased serum calcium + increased urinary calcium =

A

Primary hyperparathyroidism and Osteitis fibrosa cystica

69
Q

Infant, 46XY, small phallus, hypospadias, small testes palpated in the inguinal area, serum T normal, BP normal.

A

Defective 5-alpha reductase -> decreased DHT therefore external genitalia is not formed correctly (pseudohermaphroditism)

70
Q

Does maternal insulin cross the placenta?

A

NO

Maternal glucose DOES cross the placenta and the fetus’ pancreatic beta cells begin to secrete their own insulin (pancreatic beta cell hyperplasia)

71
Q

Prolonged ACTH stimulation of the adrenal cortex causes a of the b and c layers

A

a=Hyperplasia
b=Fasciculata
c=Reticularis

72
Q

Cortisol - anabolic or catabolic?

A

Mostly catabolic except for in the live (+GNG and glycogenesis)

Opposite of insulin.

73
Q

Insulin vs Glucagon - phosphorylator vs dephosphorylator

A 
Insulin = dephosphorylator
Glucagon = phosphorylator
74
Q

light microscopy of the thyroid: Nests or sheets of polygonal or spindle shaped cells with extracellular amyloid deposits that stain with congo red

A

Medullary thyroid carcinoma

-part of MEN2A or MEN2B

75
Q

Alcohol suppresses what reactions resulting hypoglycemia?

A

Inhibits GNG

  • inhibition of alpha-KG DH and PDH enzymes due to lack of thiamine (B1)
  • inhibition of all reactions that require NAD due to the fact ethanol -> acetyl CoA used it all up
  • inhibition of transketolase enzymes due to lack of thiamine (B1)

Alcohol does not inhibit any enzymes in the glycogenolysis pathway. This is the main route of glucose production until hepatic glycogen stores are depleted.

76
Q

Patient with increased T4, decreased radioactive iodine uptake, hyperthyroid symptoms

A

Ingestion of exogenous thyroxine (people do this for weight loss purposes)

The TSH level will also be decreased (which is related to the decreased radioactive iodine uptake)

77
Q 
TCA enzyme(s) that require niacin
(3)
A

Niacin (B3) = NAD

  • Isocitrate DH
  • Alpha-ketoglutarate DH
  • Malate DH
78
Q

TCA enzyme that requires riboflavin

A

Riboflavin (B2) = FAD

-Succinate DH requires FAD to make FADH2 (this enzyme is also complex II in the ETC)

79
Q

Lower leg skin thickening and induration + elevated T4 + decreased TSH =

A

Graves hyperthyroidsim

80
Q

Grave’s disease associated HLA subtype =

A

HLA-DR3

81
Q

Celiac disease associated HLA subtype =

A

HLA-DQ2 and DQ8

82
Q

Excessive ingestion of raw egg whites causes _ deficiency

A

Biotin (B7)
-Dermatitis, alopecia, enteritis

Enzymes that require biotin: carboxylation reactions

  • Pyruvate carboxylase
  • Acetyl CoA carboxylase
  • Propionyl CoA carboxylase
83
Q

Young child, Progressive spastic diplegia (bilateral leg stiffness), Growth delay, Abnormal chorioathetoid movements, Elevate arginine levels, Normal ammonia levels

A

Arginase deficiency

  • cannot make urea from urea cycle
  • treatment: low protein diet
84
Q

3 antioxidant enzymes:

A
  • superoxide dismutase
  • glutathione peroxidase
  • catalase

converts ROS -> O2 + H2O

85
Q

What pathway are these enzymes a part of?

  • Aldose reductase
  • Sorbitol dehydrogenase
A

Polyol pathway
-occurs in seminal vesicles, retina, lens, renal papilla, Schwann cells

glucose -(aldose reductase)-> sorbitol -(sorbitol dehydrogenase)-> fructose

Sorbitol cannot readily cross membranes so in the certain tissues, it gets stuck
-cataracts in the lens

86
Q

Pancreatic ductal secretions and absorptions during high flow

A

Secretion: HCO3-, Na+, H2O

Absorption: Cl-

87
Q

Elevated baseline/fasting insulin levels with normal glucose levels =

A

Insulin resistance

An insulinoma would have elevated insulin levels with hypoglycemia

Uworld Journal (12 decks)

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