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Clin Med-Endocrine > parathyroid > Flashcards

parathyroid Flashcards

1
Q

What is the role of PTH

A

single most important factor in regulation of serum calcium
regulated by level of ionized calcium
major target is kidney and bones

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2
Q

what is the action of PTH on the kidneys

A

increases renal calcium resorption in the tubules
increases phosphate excretion by blocking reabsorption
increases the conversion of Vit D to its active form in the kidneys which increases GI absorption of calcium

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3
Q

what is the function of PTH in the rapid phase of calcium homeostasis

A

PTH binds to receptors on the osteoblast and osteoclasts the membrane pumps Ca from the bone fluid which is transported into blood stream

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4
Q

what is the function of PTH in the slow phase of calcium homeostasis

A

osteoclasts are activated and breakdown formed bone which results in an increase in osteoclastic activity causing calcium to be released into the blood stream increasing Ca levels

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5
Q

where is the majority of calcium stored?

A

99% is in the bone

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6
Q

what percent is free

A

40%

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7
Q

what percent is bound to plasma

A

50%

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8
Q

where is vitamin D-3 cholecalciferol former

A

is formed in the skin with exposure to UV light and Vitamin D-2 is absorbed in our diet

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9
Q

Where is Vitamin D-3 activated when it undergoes hydroxylation

A

in the liver and the the kidney into its active form. Need to be activated in the kidneys in response to PTH stimulation due to low serum calcium levels and low phosphate levels

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10
Q

What is the primary action of D-3

A

is to promote intestinal absorption of calcium and phosphate and enhances bone absorption of Ca

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11
Q

As Ca levels increase what happen to PTH secretion, renal vitamin D activation, intestinal Ca absorption and renal phosphate reabsorption?

A

PTH decreases
Renal Vit-D act decrease
intest Ca abs decreases
Renal phosphate increases

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12
Q

where is majority of phosphate located

A

in bone

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13
Q

what does phophate exist as in the blood

A

phopolipids and phosphate esters and inorganic phosphate(ionized)

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14
Q

what is the function of phophate

A

acts as intra/extracellular anion buffer of the regulation of acid base balance
provides energy for muscle contraction in ATP

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15
Q

what is the function of calcitonin

A

decreased ECF calcium levels

it gets stimulated by large increases in plasma Ca levels

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16
Q

What are the targets that calcitonin acts on

A

bone: inhibits resorption by inhibiting osteoclasts
kidney: stimulates calcium and phosphate excretion in renal tubules

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17
Q

what are the 3 hormones that regulate calcium phosphate balance

A

PHT, Calcitonin and vitamin D
control absorption in intestines
controls deposition and absorption of Ca/P from bone
controls renal reabsorption and excretion of Ca/P by the kidney

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18
Q

what is the definition of hyperparathyroidism

A

abnormal hypersecretion of PTH secretion

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19
Q

what are the results of having hyperparathyroidism

A

hypercacemia hypophosphatemia (hallmark finding)

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20
Q

What happens when there is excessive PTH released what are the problems this can have with parts of the body?

A

wrist and hip fractures due to calcium loss, cystic bone lesions, kidney stones due to hypercalciuria, slowing of the nervous system and musculoskeletal system

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21
Q

what is the most common cause of elevated PTH and hypercalcia?

A

primary hyperparathyroidism

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22
Q

who are are the highest risk for hyperparathyroidism

A

people older than 40

more common in females

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23
Q

what is the most common etiology of primary hyperparathyroidism

A

parathyroid adenoma

24
Q

what are other causes of hyperparathyroidism

A

parathyroid hyperplasia

parathyroid carcinoma

25
Q

what is secondary hyperparathyroidism

A

compensatory hyper-functioniong of the parathyroid glands caused by hypocalcemia or peripheral resistance to PTH

26
Q

what is the hallmark of secondary hyperparathyroidism?

A

elevated PTH, normal to low calcium levels and high renal disease to low vitamin D absorption low phosphate levels

27
Q

what is the most common cause of secondary hyperparathyroidism

A

chronic renal insufficiency/failure

28
Q

what are other causes of secondary hyperparathyroidism

A

Vit-D deficienct or abnormal vit D metabolism
calcium malabsorption
medications (phenytoin, phenobarbital, laxitives)

29
Q

what are signs and and symptoms of primary hyperparathyroidism

A

hypercalcemia is detected by accidental blood work

most pts are asymptomatic of have mild symptoms that might be discovered in ROS

30
Q

what are things you might expect to see with primaryPTH in the kidney/urinary tract?

A

nephrolithiasis (kidney stones) polyuria, renal colic

31
Q

what are things you might expect to see with primaryPTH in the skeletal system?

A

bone loss, fractures, bone pain, muscle weakness, myalgias, arthralgias

32
Q

what are things you might expect to see with primaryPTH in the neuromuscular?

A

muscle weakness, fatigue/malaise

33
Q

what are things you might expect to see with primaryPTH in the neurologic?

A

depression, nervousness, cognitive dysfunction, physchosis, confusion, headache

34
Q

what are things you might expect to see with primaryPTH in the GI?

A

peptic disease, pancreatitis, cholelithiasis, N/V, loss of appetite, constipation, abdominal pain

35
Q

what are things you might expect to see with primaryPTH in the Cardio?

A

HTN, arrhythmias

36
Q

what is the most common presentation of 2nd hyperparathyroidism

A

renal failure,

37
Q

what are other symptoms of hyperparathyroidism

A

weaking of bones, fractures, bone pain

heart arrythmias

38
Q

what are the lab values like for primary hyperparathyroidism

A

Hypercalcemia>10.5mg/dl
Serum phosphate low<2.5mg/dl
elevated PTH

39
Q

what are the lab values like for secondary hyperparathyroidism

A

serum phosphate is high in kidney failure and low if due to absorption problems
elevated serum PTH
normal serum calcium

40
Q

what is the treatment for primary hyperparathyroidism

A

1st line is surgery

2nd line is medial therapy

41
Q

When is medical therapy used in patients

A

pts who are not candidates for surgery

or asymptomatic patients

42
Q

how is a person with hyperparathyroidism managed

A

fluids to treat hypercalcemia
bisphosphonate IV (lowers serum calcium)
Vit-D supplemetation

43
Q

what are things you want to avoid with primary hyperparathyroidism

A

Thiazides diuretics, calcium supplements

44
Q

what are things you may want to encourage your patients to do to help with hyperparathyroidism

A

staying active, hydrated, avoid immobilization

45
Q

how do you treat a person who has secondary hyperparathyroidism

A 
treat underlying condition
Medical therapy is mainstay
Vitamin D supplementation (reduce PTH levels, but may also increase calcium level and contribute to caciphylaxis
phosphate binders
Cacimimetics
46
Q

what are calcimimetics

A

attach to a receptor on parathyroid cells and increase the ability of the cells to recognize high calcium levels in the bloodstream so less PTH is made
decreases the amount of calcium in the blood

47
Q

what is the next treatment if medical therapy fails

A

surgical therapy

48
Q

what percent of asymptomatic patients will develop worsening hypercalcemia, hypercalciuria, and reduced bone density

A

1/3

49
Q

what is hypoparathyroidism

A

condition where the body does not produce enough PTH and hypocalcemia happens

50
Q

What are some causes of hypoparathyroidism

A 
thyroidectomy
autoimmune
functional due to malabsorption, alcoholism, vitamin D deficiency
congenital
exposure to heavy metals
51
Q

what are acute signs of hypoparathyroidism

A 
tetany
muscle cramps
carpopedal spasm
Irritability
altered mental status
convulsions
stridor
tinglining around mouth, hands, feet
chvosteks sign
trousseaus phenomenon
52
Q

what are chronic signs of hypoparathyroidism

A 
lethargy
personality changes
anxious
blurred vision
parkinsonism
metal retardation
nails thin and brittle
skin dry and scaly
loss of eyebrows
53
Q

what is the trousseaus phenomenon

A

carpal spasm after application of a BP cuff

54
Q

what are the lab values like for hypoparathyroidism

A

serum calcium low
serum phosphate is high
PTH level low
Urinary calcium low

55
Q

what are abnormal imaging/special tests for hypoparathyroidism

A

calcification of basal ganglia
bones may be denser than normal, cutaneous calcification
cataracts
ECG changes- prolonged QTinervals T wave abnormalitie
increased bone mineral density

56
Q

how to treat acute attacks of hypoparathyroidism

A 
maintain open airway
IV calcium gluconcate
oral calcium
Vit-D
magnesium
transplantation of cryopreserved parathyroid tissue
57
Q

What is the long term treatment for hypoparathyroidism

A

maintain serum calcium between 8-8.6mg/dl
vitamin D supp
PTH injection
avoid calcium depleting drugs(phenothiazine, furosemide)

Clin Med-Endocrine (8 decks)

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