Parathyroid

Question 1

PTH function

Answer 1

directly releases Ca from bone
renal Ca resorption (phosphate secretion)
renal conversion of 25(OH)D to 1,25(OH)D2

Question 2

causes of primary hyperparathyroidism

Answer 2

adenoma
primary hyperplasia
parathyroid carcinoma

Question 3

sx of primary hyperparathyroidism

Answer 3

bones - osteoporosis/osteitis fibrosis cystica
stones - nephrolithiasis
groans - constipation, gallstones
moans - depression, lethargy, seizures

Question 4

parathyroid adenoma

Answer 4

benign neoplasm of parathyroid chief or oxyphil cells
normal and abnormal tissue may be present
usually affects one gland
due to germline or somatic mutations in MEN1

Question 5

parathyroid hyperplasia

Answer 5

presents in multiple glands
MEN syndrome may be responsible
abnormal tissue only

Question 6

what is more common: primary or secondary parathyroid hyperplasia?

Answer 6

secondary

Question 7

parathyroid carcinoma

Answer 7

metastasis is most telltale sign!

elevated PTH that doesn’t go down after surgery

Question 8

non-parathyroid hypercalcemia causes

Answer 8

malignancy
vitamin D excess
calcium excess
medication (thiazide diuretics)

Question 9

humoral hypercalcemia of malignancy

Answer 9

PTHrP mediated - SSC

vitamin D mediated - lymphomas

Question 10

local osteolytic hypercalcemia

Answer 10

osteoclastic bone resorption due to:
breast carcinoma
multiple myeloma

Question 11

cause of secondary parathyroid hyperplasia

Answer 11

*reduced kidney function
gastric bypass
vit D deficiency
pseudohypoPTH

Question 12

presentation of secondary hyperparathyroidism

Answer 12

dissecting osteitis/”rugger jersey sign”

calciphylaxis - calcific occlusion of blood vessels causing ischemic necrosis

Question 13

describe tertiary hyperparathyroidism

Answer 13

prolonged hypocalcemia causes continuous production of PTH even when Ca levels have normalized

Question 14

clinical features of hypocalcemia

Answer 14

behavioral disturbance/stupor
numbness/parasthesias
muscle cramps/spasms
convulsions

Question 15

PE findings of hypocalcemia

Answer 15

Trosseau sign
Chvostek sign
Prolonged QT interval on EKG

Question 16

causes of acquired primary hypoparathyroidism

Answer 16

iatrogenic (surgical)

autoimmune

Question 17

causes of congenital primary hypoparathyroidism

Answer 17

DiGeorge syndrome
CaSR mutation
familial isolated hypoparathyroidism

Question 18

describe CaSR LoF mutation

Answer 18

hypercalcemia and hypocalcuria

• parathyroid thinks there isn’t enough Ca when there is
• turns on PTH and reduces renal excretion

Question 19

describe CaSR GoF mutation

Answer 19

hypocalcemia and hypercalciuria

• parathyroid thinks there’s plenty of Ca when there isn’t
• turns off PTH and increases renal excretion

Question 20

pseudohypoparathyroidism

Answer 20

PTH resistance in renal tubular cells and bone

hypocalcemia and hyperphosphatemia despite normal or elevated PTH

Question 21

what disease and mutation is associated with pseudohypoparathyroidism

Answer 21

Albright hereditary osteodystrophy

*GNAS mutation

Question 22

presentation of Albright’s hereditary osteodystrophy

Answer 22

*short stature
*obesity
*short phalanges of UE and LE
dental abnormalities
subcutaneous ossifications
cataracts
seizures and tetany