parathyroid glands

Question 1

which pharyngeal pouches make the parathyroid gland ?

Answer 1

3rd and 4th pharyngeal pouch

Question 2

where are the receptors of the PTH ?

Answer 2

bone and kidney

Question 3

what cells make the PTH ?

Answer 3

chief cells

Question 4

what is the net effect of PTH ?

Answer 4

increased calcium levels in plasma
lowers phosphate levels in the plasma , by increasing the excreted levels of it in the urine

Question 5

what are the different triggers for the secretion of the parathyroid hormone ?

Answer 5

low levels of calcium
high levels of phosphate
low levels of vitamin D

Question 6

what is the effect of magnesium on the parathyroid gland ?

Answer 6

high magnesium means less PTH secreted ( like calcium)

Question 7

what is the effect of very low levels of magnesium on the PTH release ?

Answer 7

super low magnesium levels inhibits the release of the PTH
hypocalcemia is often seen with severe hypomagnesemia

Question 8

what is the effect of low calcium and low magnesium on the ecg ?

Answer 8

prolonged QT interval

Question 9

what is the effect of PTH on the kidney ?

Answer 9

increased calcium absorption
decreased phosphate absorption
increased vitamin d production

Question 10

what is the effect of PH on the GI tract ?

Answer 10

increased calcium and phophate absoption

Question 11

what is the effect of PTH on bones ?

Answer 11

it binds to the osteoblasts which then expresses RANk-L on their surface
which binds to RANK receptor on osteoclasts which breaks down bones and hence increase serum calcium

Question 12

what is the blood supply of the parathyroid ?

Answer 12

superior and inferior thyroid arteries

Question 13

how does PTH affect the levels of vitamin D ?

Answer 13

PTH upregulates the expression of 1 alpha hydroxylase in the kidneys to form the more active form of vitamin D

Question 14

how can the activation of vitamin D happen independently ?

Answer 14

in cases of sarcoidosis

Question 15

what is the difference in the effect of bones with different doses of PTH ?

Answer 15

continous administration leads to bone resorption

low dose once daily leads - bolus administration leads to an increase on bone mass

Question 16

what are the different cells found in bones and what are their functions ?

Answer 16

osteoblasts - make the bone , have parathyroid hormone receptors
osteoclasts bykasar

Question 17

how do the osteoblasts and osteoclasts work together ?

Answer 17

the osteoblasts secrete M-CSF , which stimulates the osteoclasts
osteoblasts have an RANK-L receptor which also binds to osteoclasts to activate it

Question 18

what is PTHrP ?

Answer 18

hormone produced in large amounts in tumors
leads to hypercalcemia

Question 19

what are the three forms of hyperparathyroidism ?

Answer 19

primary - overactive gland
secondary - hypocalcemia
tertiary - renal failure

Question 20

what are the common causes of primry hyperPTH ?

Answer 20

parathyroid adenoma

Question 21

what are the associated serum findings in primary hyperPTH ?

Answer 21

hypercalcemia
phosphaturia
high or normal calcium levels in the urine

Question 22

what is the classic presentation of primary hyperPTH ?

Answer 22

Stones ,bones, groans , psychiatric overtones

Question 23

what is the specific bone disease associated with 1ry hyperPTH ?

Answer 23

osteitis fibrosa cystica
associated with brown tumors

Question 24

where exactly is the pathology in association with osteitis fibrosa cystica ?

Answer 24

subperiosteal bone resorption

Question 25

what does groans refer to in 1ry hyperPTH ?

Answer 25

constipation recurrent gastric ulcers

Question 26

what is the treatent for 1ry hyperPTH and what are the associated complications ?

Answer 26

treatment: parathyroidectomy risk of recurrent laryngeal nerve damage post op hypocalcemia

Question 27

what is the presentation of post parathyroidectomy hypo calcemia ?

Answer 27

numbness or tingling in the fingers, toes and hands twitching or cramping of facial muscles

Question 28

what is the cause of tertiary hyperPTH ?

Answer 28

secondary hyperPTH w tawel awy bas hena VERY hig PTH high PTH and high calcium like with primary

Question 29

what is the pathology in terms of renal failure in calcium phosphate ?

Answer 29

increased phosphate , decreased vitamin D levels decreased calcium from the gyt , decreased calcium from the plasma causing hypocalcemia increase in PTH

Question 30

what is familial hypocalciuric hypercalcemia ?

Answer 30

autosomal dominant disorder abnormal calcium sensing - due to abnormal CaSR receptors

Question 31

what are the levels of of phosphate in the urine in hyperPTH ?

Answer 31

increased phosphate levels increased cAMP

Question 32

what are the calcium levels in FHH ?

Answer 32

high serum calcium normal PTH low level of calcium in the urine

Question 33

what is the key finding associated with FHH ?

Answer 33

low urinary calcium

Question 34

what are the calcium levels in hypopituitarism ?

Answer 34

low PTH secretion low calcium levels

Question 35

what are the signs and symptoms of hypocalcemia ?

Answer 35

neuromuscular irritability - tingling and spams tetany seizures

Question 36

what are the specific signs seen in hypocalcemia ?

Answer 36

trousseau's sign - hand spams with BP cuff inflation chvosteks sign - facial contraction on nerve tapping

Question 37

what are the common causes of hypoparathyroidism ?

Answer 37

surgical excision after thyroid surgery hemochromatosis wilsons disease metastatic cancer

Question 38

what is autoimmune polyendocrine syndrome type 1 ?

Answer 38

autosomal recessive disorder mutation of the AIRE gene

Question 39

what is the triad associated with APS-1?

Answer 39

mucocutaneoux candidiasis autoimmune hypoparathyroidism addison's disease

Question 40

what is digeorge syndrome ?

Answer 40

failure of the 3rd and 4th pharyngeal pouches the triad : loss of thymus loss of parathyroid congenital heart defect

Question 41

what is the treatment for hypoparathyroidism ?

Answer 41

calcium and calcitrol recombnant human PTh

Question 42

what is pseudohypoparathyroidism ?

Answer 42

group of disorders kidney and bone unresponsive to PTH abnormal PTH receptor function

Question 43

what are the calcium and PTH levels in pseudohypoPTH ?

Answer 43

high PTH levels and low calcium levels

Question 44

what is albrights hereditary osteodystrophy ?

Answer 44

form of pseudohypoparathyroidism autosomal dominant hypocalcemia and hyperphosphatemia

Question 45

what are the clinical features associated with AHO ?

Answer 45

short stature shortened fourth and fifth metacarpals rounded facies mild mental retardation this is a form of pseudohypoparathyroidism

Question 46

why is there an increase in vitamin D levels in sarcoidosis ?

Answer 46

due to the independant activation of vitamin d where histiocytes activate the 1 alpha hydroxlase enzyme

Question 47

what are the PTH levels in sarcoidosis ?

Answer 47

PTH is suppressed due to the increased levels of calcium we have hypercalcemia due to the increased production of vitamin D

Question 48

which cancers are associated with the release of PTHrp ?

Answer 48

squamous cell carcinoma of the lung and renal cell carcinoma

Question 49

what is the classic scenario associated witha patient who has pagets disease ?

Answer 49

a man over the age of 50 who's hat doesn't fit him anymore with tinnitus due to narrowing of the acoustic foramen

Question 50

what is the effect seen upon administration of exogenous calcium ?

Answer 50

as expected : the serum calsium will increase the PTH levels will decrease an increase in vitamin D

Question 51

what is the classic scenario associated with milk alkali syndrome ?

Answer 51

hypercalcemia and metabolic alkalosis ( high bicarb) associated with a patient taking too many antacids for GERD

Question 52

what are the expected serum calcium and PTH levels in a patient after space travel ?

Answer 52

decreased bone density decreased calcium levels decreases PTH decreased urinary cAMP

Question 53

what are the features of osteporosis ?

Answer 53

all the levels are normal 7ata el calcium but decreased osteoblast activity increased osteoclast activity and increased RANK L activity

Question 54

what type of patient is at a higher risk of low magnesium levels ?

Answer 54

alcoholics