Parathyroid Flashcards

1
Q

What is the primary stimulator of PTH release?

A

-low free serum Ca

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2
Q

What are the 4 physiologic actions of PTH?

A
  • bone resorption (Ca+phosphate)
  • Ca REABSORPTION in the DCT
  • phosphate EXCRETION in PCT
  • adding 1-OH to activate Vitamin D
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3
Q

What type of bone cell does PTH stimulate?

A

osteoClasts

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4
Q

What enzyme in the PCT of kidney is stimulated by PTH?

A
  • 1a-hydroxylase

- adds an -OH @ position 1 to 25-OH Vitamin D

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5
Q

When is the only time that Calcitonin plays a role in the body?

A

-if Ca levels are super hi, it will reduce osteoClast activity

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6
Q

What 3 diseases can benefit from Calcitonin administration?

A
  • Osteoporosis
  • Paget’s disease of bone
  • malignancies with hyperCa
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7
Q

PTH is to Chief cells of the parathyroid as Calcitonin is to __________

A

-C cells of the THYROID

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8
Q

What the hell is parathyroid related peptide (PTHrP)?

A
  • secreted by many cancerous tissues

- causes hyperCa

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9
Q

Why do patients with renal failure have bone problems?

A

-less active Vitamin D, become hypoCalcemic

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10
Q

Patients with renal failure will have high levels of what in the blood?

A
  • hi PTH
  • hi 25-OH Vitamin D (inactive)
  • hi phosphate
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11
Q

Vitamin D acts where and does what?

A
  • intestine

- increases absorption of BOTH Vitamin D +Phosphate

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12
Q

What 2 ions inhibit ADH at the collecting duct and cause polyurea?

A
  • HypoKalemia

- HyperCalcemia

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13
Q

Describe a patient with primary hyperPTH.

A
  • most are asymptomatic!
  • BONES (osteoporosis)
  • STONES (nephrolithiasis)
  • GROANS (constipation)
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14
Q

If a pt with primary hyperPTH is asymptomatic, what tx?

A

NONE

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15
Q

What does hypoCalcemia do to your nerves?

A

HYPERexcitable (+Chvostek’s sign on face, +Trousseau sign with bp cuff on arm)

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16
Q

Primary hyperparathyroidism presents commonly as what triad?

A

-Stones, bones, and groans

Ca-oxolate kidney stones, cystic bone spaces, constipation

17
Q

What 4 lab values to look for in a Parathyroid adenoma?

A
  • hyperCa
  • hypoPhosphatemia
  • hi alk phos
  • hi urinary cAMP (say whaaaa)
18
Q

What are Chief Cells?

A
  • cells of parathyroid

- secrete PTH

19
Q

What are parafollicular (C) cells?

A
  • cells near the follicles in the thyroid
  • secrete Calcitonin
  • cancer=medullary carcinoma of thyroid (MEN II)
20
Q

What is the number 1 cause of secondary hyperparathyroidism?

A

-Chronic renal failure

21
Q

Describe the 2 mechanisms by which renal failure leads to secondary hyperparathyroidism.

A
  • renal failure = less excretion of Pi (more Pi=more gobbling up of free Ca)
  • renal failure = less 1-OH added to Vitamin D (no active Vit D = less Ca absorption in gut)
  • less free Ca = more PTH