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Endocrine-Week 1/2 > Modules (Week 2) > Flashcards

Modules (Week 2) Flashcards

1
Q

What cells in the Parathyroids synthesize, store and secrete PTH

A

Chief cells

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2
Q

Main functions of PTH are to (increase/decrease) Calcium and (increase/decrease) phosphorus

A

Inc. Calcium

Dec. Phosphorus

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3
Q

Where does PTH act?

A
  1. Bone-direct effect (inc. bone resorption to inc. Ca and Phosphorus release)
  2. Kidney-direct effect (inc. Ca reabsorption and Phosphorus excretion; inc. Vit D activation)
  3. Gut-indirect effect (inc. Ca and Phosphorus absorption via Vit D activation)
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4
Q

Function of PTH on bone

A

Direct effect on bone:

  • Inc. bone resorption
  • Inc. Ca and Phosphorus release
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5
Q

Function of PTH on Kidney

A

Direct effect on kidneys:

  • Inc. Ca reabsorption
  • Inc. Phosphorus EXCRETION
  • Activate Vitamin D
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6
Q

Function of PTH on Gut

A

INDIRECTLY inc. Ca and Phosphorus absorption via Vitamin D

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7
Q

(Calcium/Phosphorus) is the MAIN regulator of PTH via a Negative feedback loop

A

Calcium (too little, need to conserve and retain)

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8
Q

(Calcium/Phosphorus) is a regulator of PTH via a Positive feedback loop

A

Phosphorus (too much, need to excrete)

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9
Q

Calcium binds to ______________ _________________ ________________ on Chief cells to regulate PTH

A

Calcium-Sensing Receptor (CaSR)

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10
Q

What is the Diagnostic Approach for a potential Parathyroid issue?

A

1) High/Low/Normal calcium?

2) If normal calcium, is there abnormal PTH or Vitamin D?

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11
Q

How is Calcium regulated/stored in ECF

A

Protein bound (~40%)
Ionized (free/bioactive) (~50%)
Complexed (with anion like PO4, HCO3, lactate) (~10%)

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12
Q

(Low/High) albumin is the most common cause of apparent hypocalcemia or “pseudohypocalcemia”

A

Low albumin (due to overall lower measured TOTAL calcium without a true change in overall body calcium)

Ionized (free) calcium does not change! (so no symptoms of hypocalcemia)

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13
Q

Free calcium (increases/decreases) with alkalemia

A

Decreases (protein-bound Ca increases)

  • symptoms of hypocalcemia can occur!
  • but TOTAL calcium does NOT change!
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14
Q

Free calcium (increases/decreases) with acidemia

A

Increases (protein-bound Ca decreases)

*but TOTAL calcium does NOT change!

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15
Q

Function of Phosphorus

A

Bone structure

ATP generation

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16
Q

Hormones that regulate Phosphorus levels

A

decreased by PTH (renal excretion)

increased by Vit. D (gut absorption)

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17
Q

Renal failure, Hypoparathyroidism and Vit. D toxicity result in (low/high) Phosphorus

A

High Phosphorus (lots of gut absorption, little renal excretion)

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18
Q

Hyperparathyroidism and Vit. D deficiency result in (low/high) Phosphorus

A

Low (little gut absorption, lots of renal excretion)

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19
Q

Function of Magnesium

A

Catalyze actions of cellular enzymes (utilizing or synthesizing ATP)

20
Q

SEVERE (Hyper/Hypo)magnesemia can blunt PTH release

A

Hypomagnesemia

21
Q

Chronic Kidney Disease (elevated creatinine) can result in (high/low) levels of PTH

A

High PTH (to stimulate kidneys b/c of decreased serum calcium & increased serum phosphorus due to kidney disease)

22
Q

The activation of Vitamin D from Cholecalciferol (skin) or Ergosterol (supplement) requires….

A

2 hydroxylation steps

  • one in liver by 25-hydroxylase
  • one in kidney by 1 a-hydroxylase
23
Q

Pro-hormone and storage form for Vitamin D

  • indicator of vitamin D status
A

25-OH-D3 (cholecalciferol) OR 25-OH-D2 (ergosterol)

  • this occurs in the liver by 25-hydroxylase
24
Q

Chemical formula for Vitamin D and biologically active form

  • indicator of calcium disorders
A

1,25-OH2-D3 (cholecalciferol) OR 1,25-OH2-D2 (ergosterol)

  • this occurs in the kidney by 1 a-hydroxylase
  • this step is stimulated by PTH
25
Q

What can cause low Vitamin D levels (storage vs. bioactive forms)

A

Storage Form:

  • Dec. sun exposure
  • Dec. Vitamin D intake
  • Malabsorption
  • Liver disease

Bioactive Form:

  • Dec. kidney function
  • Dec. PTH
26
Q

How is Parathyroid Hormone-Related peptide different from PTH

A

Same effect on bone and kidney, BUT less likely to stimulate bioactive form of Vitamin D (1, 25-OH-D) so less effect (although indirect) on intestine

27
Q

Function of Parathyroid Hormone-Related Peptide

A
  1. Same effect on bone and kidney as PTH.
  2. Teeth eruption, mammary gland development and lactation
  3. PTH-RP is increased in humoral hypercalcemia of MALIGNANCY
28
Q

Cells that secrete Calcitonin

A

C-Cells (Parafollicular cells of Thyroid)

29
Q

Roles of Calcitonin

A

OPPOSITE of PTH at bone, kidney, and gut
- Overall: lower serum Calcium

  • Can be used as a marker for monitoring medullary thyroid cancer recurrence
30
Q

Iodine is transported into the thyroid cells via what transporter?

A

Na/I- symporter

31
Q

What enzyme catalyzes the reaction of Thyroglobulin and Iodine to T3/T4

A

Thyroid Peroxidase

32
Q

(T3/T4) has a very short half-life, around 1 day

A

T3

33
Q

(T3/T4) is the vast majority of thyroid hormone secreted

A

T4

*is pro-hormone and must be converted to T3

34
Q

(T3/T4) is the pro-hormone and must be activated into the biologically active form

A

T4

35
Q

(T3/T4) is the biologically active form

A

T3

36
Q

What are the “4 B’s” of Thyroid hormone action

A

Brain maturation
Bone growth
Beta-adrenergic effects (cardiac)
Base metabolic rate

37
Q

What labs do you want to run to assess Thyroid function?

A 
TSH
TBG-T3 and T4
Free T3 and T4
Thyroid antibodies
Thyroid tumor markers
38
Q

Functions of TSH (Thyroid Stimulating Hormone)

A

Stimulate thyroid hormone synth/release

Growth and vascularity of thyroid

39
Q

The majority of T3/T4 is bound to..

A

Thyroxine Binding Globulin (TBG)

40
Q

What can caused an Increase in Thyroid Hormone Binding proteins

A

ESTROGEN

Pregnancy

41
Q

What can cause a Decrease in Thyroid Hormone Binding proteins

A

ANDROGENS
Glucocorticoids
Chronic Liver Disease

42
Q

Why is measuring TSH the BEST test to diagnose and follow primary disorders in Thyroid Function?

A

Reflects long-term feedback of T3/T4 on pituitary in the recent past

*also have opposite, logarithmic change in TSH vs. T3/T4

43
Q

Antibodies seen in Autoimmune Thyroid Disease (2 total)

A

Thyroid Peroxidase antibodies (TPOAb)*
TSH-Receptor antibodies (TRAb)*
Thyroglobulin Antibodies (TgAb)

*best indicators

44
Q

Which antibody is present in 90-95% of Autoimmune Thyroid Disease

A

Thyroid Peroxidase Antibodies (TPOAb)

45
Q

TSH Receptor Antibodies are inhibitory and decrease the activity of the Thyroid (True or False)

A

False; can actually be either Stimulating (TSI) or Inhibitory (TBII)

46
Q

What are the Thyroid Tumor markers used for SURVEILLANCE (2 total)

A

Thyroglobulin (papillary/follicular thyroid cancer)

Calcitonin (MTC)

Endocrine-Week 1/2 (18 decks)

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