Parathyroid (HYPOcalcemia)

Question 1

In response to LOW Ca+ levels the Parathryoid will increase release of PTH and acts on which body systems to increase Ca levels?

Answer 1

Bone: increase resorption

Intestine: increase absorption or Ca and PO4

KIdney: incrase 1,25 dihydroxycholecalciferol, Increase Ca+ reabsorption, decrease PO4resporption

Question 2

• Neuromuscular irritability - paresthesias, muscle cramps, tetany •

Lowered seizure threshold

• Mental status changes
• Cardiac - prolonged QT, arrhythmias, CHF
• Basal ganglia calcification
• Cataracts
• Positive Chvostek’s and Trousseau’s signs

Answer 2

signs of HYPOcalcemia

Question 3

Primary hypocalcemia is caused by:

Answer 3

H a deficiency in PTH secretion: Primary hypoparathyroidism (iatrogenic, idiopathic, or familial)

Question 4

Secondary Hyperparathyroidism reults in _____of PTH secreation and LOW calcium

Answer 4

Increase

Question 5

Causes of secondary hyperparathroidism

Answer 5

Secondary hyperparathyroidism (very common – renal failure [cannot produce adequate 1,25(OH)2D], malabsorption [e.g. sprue]) Vitamin D deficiency

Question 6

Labs come back:

Low serum Ca++

elevated/normal serum PO4

Low PTH

Normal 25 (OH)D3

Answer 6

Hypoparathryoidism

Question 7

Labs:

Low Ca+

Elevated/normal PO4

Elevated PTH

Normal 25,0H

Answer 7

Pseudohypoparathyrodism

Question 8

Labs

Low Ca+

N or Low PO4

Elevated PTH

LOW 25, OH D3

Question 9

What do we see on the xray, what caused it?

Answer 9

: Basal Ganglia Calcification from Hypoparathyroidism

Question 10

A postive Chvostek or Troussuea are signs of

Answer 10

Hypocalcemia

Question 11

Causes of Hypoparathryoidism

Answer 11

• Genetic disorders • Autoimmune • Infiltrative • Pseudohypoparathyroidism

Question 12

Pseudohypoparathyroidism (PTH resistance) – Type 1a has_____ mutation and Albright’s Hereditary Osteodystrophy (AHO)

Answer 12

GNAS

Question 13

Pt comes in with HYPOcalcemia, you order what test?

Answer 13

PTH!!!

Question 14

You order PTH test on pt with Hypocalcemia, comes back LOW; what could cause this?

Answer 14

LOW Ca+

LOW PTH

–> HypoParathyroidism but rule out Mg deficiency

Question 15

Pt with Hypoparathryroidism have ____ Ca+ and _____PTH

Answer 15

Low Ca

Low PTH

Question 16

Pt has hypocalcemia with HIGH PTH, what should would look at to determine if this is 2nd hyperparathryoidism or renal insufficiency?

Answer 16

look at serum PHosphate levels

HIgh phosphate: think PTH resistanc or renal insufficiency

Low phosphate; more likley 2nd hyperparathryoidism

Question 17

Pt with renal insufficiency has HYPOCa+, what do we expect their PTH and Phosphate lelvels to be?

Answer 17

HIgh PTH

High Phosphate

Question 18

What labs suggest pt had 2nd Hyperparathyroidism

Ca

PTH

Phosp

Answer 18

Low Ca

HIgh PTH

Low Phosphate

Question 19

You think your pt may have 2nd hyperparathryoidsm as they ahve low Ca, High PTH and Low Phosphate, what else do we need to consider?

Answer 19

A vit D deficiency or occult malabsopriton; measure teh 25 (OH) vit D levels and get a 24 hr urine calcium and creatinine

*look at BMD and screen for celiacs

Question 20

Acute hypocalcemia is initially managed with

Answer 20

IV calcium gluconate

Question 21

Chronic hypocalcemia due to hypoparathyroidism is treated with calcium supplements and either

Answer 21

vitamin D2 or D3 or calcitriol

Question 22

Made by osteocytes, increases urinary phosphate excretion decreases renal production of 1,25(OH)2D

Answer 22

Fibroblast-growth factor 23 (FGF23)

Question 23

Excess FGF23 causes_______ and impaired bone mineralization (genetic forms of rickets, tumor-induced osteomalacia)

Answer 23

hypophosphatemia

Question 24

What is the result of low FGF23 action?

Answer 24

Decreased FGF23 action causes hyperphosphatemia and tumoral calcinosis

Question 25

tumoral calcinosis is seen on xray and is a result of?

Answer 25

decreased FGF23

Question 26

What can cause hypOphosphatemia?

Question 27

IV glucose and adminstration of catecholamines (epi, dopamine, albuterol) have what effect on Phoshate levels

Answer 27

Lower them

Question 28

–PTH/PTHrP-independent hypophosphatemia can be cause by:

Answer 28

Excess FGF23 or other “phosphatonins”

Intrinsic renal disease that causes phos wasting

Question 29

Causes of Hyperphosphatemia:

Answer 29

Impaired renal excreation

vit D intox

Sarcoidosis or other granulmatous disese

Massive extracellular fluid phosphate loads

Transcellular phosphate shifts

Question 30

PTH goes to bone which will increase its FGF23 activity:

what effect does FGF23 have on 1,25 dihydroxyvitamin D?

on PO4 reabsorption in gut?

Answer 30

DECREASES 1,25 dihydroxyvitamin D (while PTH increases)

INCREASES PO4 reabsorption in gut (PTH tries to decrease)