Calcium and Parathyroid

Question 1

When Ca receptors on PTgland sense low calcium, what happens

Answer 1

increase in parathyroid hormone release –> will increase renal calcium absorption and increased bone resorption/release of calcium, increase formation of active form of VitD

Question 2

Vitamin D hydroxylation

Answer 2

2 hydroxylations: 1st in liver, 2nd in kidney (second hydroxylation stimulated by PTH)

Question 3

Calcitriol/Vitamin D

Answer 3

increases calcium absorption in gut –> increase serum calcium

Question 4

Hyperparathyroidism

Answer 4

“bones, groans, stones, and psychic moans” –> abnormal PTH hypersecretion –> hypercalcemia

Question 5

Most primary hyperthyroidism is caused by

Answer 5

solitary (single PT) adenoma (85%), diffuse hyperplasia (15%), parathyroid carcinoma <1%

Question 6

T/F in pt adenoma, may have hypertrophy of other pt glands

Answer 6

F –> atrophy b/c of negative feedback from high calcium due to hyperactive pt

Question 7

hypercalcemia can lead to increase/decrease in ECF phosphate

Answer 7

decrease –> increased urinary phosphate is an effect of pth and overrides the phosphate released from bone with calcium

Question 8

Groans

Answer 8

increased PTH can increase bp, constipation, GI tone

Question 9

Classical presentation of primary hyperparthyroidism

Answer 9

osteitis fibrosa cystica –> bone demineralization with subperiosteal bone resorption and bone cysts

Question 10

Realistic presentation of primary hyperparathyroidism

Answer 10

elevated serum calcium, kidney stones, renal dysfunction, reduced bone mineral density (cortical bone)

Question 11

Tx of hyperparathyroidism

Answer 11

asymptomatic: medical monitoring // surgery for kidney stones, fracture in symptomatic patients or asymptomatic patients<50 years with severe hypercalcemia or reduced creatinine clearance or low bone mass

Question 12

Secondary hyperparathyroidism

Answer 12

hyperfunctioning Pt glands are compensating for hypocalcemia: renal insufficiency, calcium malabsorption, vitamin D deficiency

Question 13

Tertiary hyperparathyroidism

Answer 13

gland hyperfunction and hypersecretion due to prolonged secondary hyperparathyroidism –> gland autonomy –> elevated calcium, requires surgery

Question 14

Familial hypocalciuric hypercalcemia

Answer 14

autosomal dominant –> looks like primary hyperparathyroidism –> abnormal calcium sensor –> increase in calcium setpoint –> increased pth secretion –> elevated calcium –> low urine calcium

Question 15

Difference between FHH and Primary hyperparathyroidism

Answer 15

low urine calcium in FHH –> calcium sensor in kidney also broken –> cannot flush out calcium

Question 16

Hypoparathyroidism

Answer 16

following total thyroidectomy or radical neck dissection, infiltrative (hemochromatosis or wilson’s), congenital (digeorge, familial type 1 polyendocrine)

Question 17

Hypocalcemia effects

Answer 17

cardiac arrhythmia, neuromuscular irritability/tetany

Question 18

Chvostek sign

Answer 18

irritable facial nerve due to hypocalcemia

Question 19

Trousessau’s sign

Answer 19

carpal spasm due to hypocalcemia

Question 20

Trousseau or Chvostek is more specific

Answer 20

Trousseau –> but takes a whole 3 minutes in the clinic

Question 21

Tx of hypoparathyroidism

Answer 21

oral calcium, vitamin D,monitoring urinary/serum calcium,

Question 22

Goal is serum calcium level in patient with hypoparahtyroidism

Answer 22

low normal –> will lose a lot of calcium in the urine b/c of absence of pth –> want to avoid kidney stones so go low normal

Question 23

Vitamin D intoxication

Answer 23

uncommon cause of hypercalcemia –> nausea, vomiting, weakness, AMS

Question 24

sequelae of Vitamin D intoxication

Answer 24

stored in fat –> cannot chelate it –> prolonged hypercalcemia

Question 25

Tx of D intoxication

Answer 25

hydration, no dietary calcium

Question 26

Vitamin D deficiency

Answer 26

lack of sun, decreased intake/absorption of vitamin D, metabolic defects in vitamin D hormone system –> leads to secondary hyperparathyroidism

Question 27

Sequelae of vitamin d deficiency

Answer 27

rickets in children, osteomalacia in adults –> widened osteoid (demineralized bone) seams and impaired mineralization, risk of osteoporosis

Question 28

_______ is important in mineralization of devoid bone matrix to lay down calcium.

Answer 28

Vitamin D

Question 29

Characteristic signs of osteomalaci

Answer 29

diffuse bone pain and tenderness, proximal muscle weakness, Looser-Milkman pseudofractures perpendicular to bone surface

Question 30

Tx of Vitamin D deficiency

Answer 30

treat underlying disorder, calcium, vitamin D