parathyroid

Question 1

Number of PTH glands

Answer 1

Normal: 4
5%: 3
4% 5

Question 2

Primary targets for PTH (Parathyroid hormone)

Answer 2

Bone and Kidneys

Question 3

PTH effect on bones

Answer 3

Mobilize Ca

Question 4

PTH effect on kidneys

Answer 4

Increase absorption of Ca
Increase phosphate excretion
Enhance 1a-hydroxilation of 25 hydroxy vit D

Question 5

Vitamin D

Answer 5

Steroid hormone
D3 and D2 forms
Synthesized from sunlight
1,25 (OH) VD natual ligand for receptor (functional form)

Question 6

Vit D3

Answer 6

Rare in nature
More potent than D2
from liver and seafood

Question 7

Vit D2

Answer 7

Less potent than D3
From edible mushrooms

Question 8

Vit D pathway

Answer 8

7-Dehydrocholesterol + UVB -> Vit D3 -> (liver) Vit D3 +25 hydroxylase -> 25 (OH) Vit D -> (kidney) 25 (OH) Vit D +1a hydroxylase -> 1,25 (OH)2 Vit D

Question 9

Vitamin D Effects

Answer 9

Active absorption of Ca
Absorption of phosphate (less dependent)
Stimulate osteoclast precursors

Question 10

PTH effects on the GI tract

Answer 10

Required for normal function
absorption of Vit D and Ca
Disease states: short bowel syndrome, gastric bypass, intestinal mucosal disease, genetic defects, bowel fistula

Question 11

Bone physiology

Answer 11

Osteoblasts build bone
Osteoclasts break bone down
Coupled response - ensures bone is built and broken at the same time
Bone turnover markers are monitored for therapies

Question 12

Bone turn over markers

Answer 12

ALP
Osteocalcin
Procollagen N- terminal peptides

Question 13

Bone resorption markers

Answer 13

Hydroxyproline
Telopeptide
pyridinium crosslinks
TRAP

Question 14

Bone Types

Answer 14

Cordical Bone: Shafts. Predominant type. Strong and lightweight
Trabecular: Vertebrae. honeycomb, weightbearing

Question 15

Hypercalcemia

Answer 15

Elevated blood Ca
Lethargy, stupod, coma, intellectual weariness, nausea, anorexia, etc
PHPT most common cause

Question 16

Primary Hyperthyroidism (PHPT)

Answer 16

Autonomous overproduction of PTH
3x more likely in women
diagnosis made w/ elevated blood Ca and inappropriately or normal PTH

Question 17

Biochem marker for PHPT

Answer 17

Hypercalcemia
Hypophosphatemia
elevated PTH relative to serum
Abnormal 1,25 OH vit D
Detected through sandwich ELISA and Electrochemiluminecense

Treated through parathyroidectomy - cure

Question 18

PHPT important points

Answer 18

Insidious onset and gradual prog
20-30% have kidney stones
bone loss from Cortical > Trabecular
single glad tumor common at 85%

Question 19

Secondary Hyperparathyroidism

Answer 19

Hypocalcemia
Rise in PTH in response to outside factors

Question 20

Secondary Hyperparathyroidism effects

Answer 20

Low blood Ca and phosphate
elevated ALP
Hypocalciuria and phosphaturia
Vit D deficiency or disfunction

Question 21

Chronic Kidney Disease (CKD)

Answer 21

Failure to adequately create functional Vit D or excrete phosphate
Secondary hyperparathyroidism

Question 22

Familial Hypocalciuric Hypercalcemia (FHH)

Answer 22

Low urine Ca
No end organ damag
Multiple family members effected
elevated Mg
Surgery ineffective

Question 23

Parathyroid Hormone related protein (PTHrP)

Answer 23

secreted by cancers
Similar to N terminal on PTH
Does not cause the PTH feedback loop (continued bone reabsorption when at suppression of PTH)

Question 24

Causes of hypoparathyroidism

Answer 24

Thyroidectomy
Accidental removal of glads
damage to glads during surgery
Autoimmune destruction (addison’s, Hashimoto’s, Type 1 diabetes)

Question 25

Metabolic bone disorders

Answer 25

Rickets: Children before plate closure
Osteomalacia: abnormal mineralization in adults
Osteoporosis: porous bones

Question 26

Rickets/Osteomalacia

Answer 26

Vit D defficiency
hypocalcemia
Secondary hyperparathyroidism
Bow legs or knocked knees

Question 27

Osteoporosis

Answer 27

most prevalent bone disease in adults
4:1 females to males
malformation or excessive bone reabsorption
disease associated: Cushing’s, Hyperparathyroidism, hyperthyroidism, mast cell malignancies, etc