11/15: Calcium and Phosphorus II

Question 1

How does chronic kidney disease affect calcium and phosphate homeostasis?

Answer 1

By disrupting the Ca and Pi reabsorption process

Question 2

What defines hypocalcemia?

Answer 2

When total serum calcium concentrations are less than 8.5 mg/dL
Or serum ionized calcium less than 4.4 mg/dL

Question 3

What are the symptoms of hypocalcemia?

Answer 3

Muscle cramps
Increased neuromuscular excitability Muscle spams
Fatigue
Cardiac dysfunction
Depression, psychosis, seizures

Question 4

what is hypoparathyroidism?

Answer 4

Undersecretion of PTH

Question 5

what leads to hypoparathyroidisms?

Answer 5

Hypocalcemia that also has serum PTH that is really low

Question 6

what are the common causes of hypoparathyroidisms?

Answer 6

autoimmune

Question 7

what is DiGeorges syndrome?

Answer 7

Congenital disease that causes a lack of the parathyroid glan

Question 8

Is hypoparathyroidism associated with CaSR mutations?

Answer 8

yes

Question 9

how is hypoparathyroidism associated with CaSR mutations?

Answer 9

By consitutively activating CaSR causing hypocalcemia since PTH becomes
inhibited leading to low Ca reabsorption

Question 10

How do you treat hypoparathyroidism?

Answer 10

Calcium and calcitriol

Question 11

What occurs in this disease (hypocalcemia)?

Answer 11

Serum PTH is high to overcome the resistance to increase low Ca levels

Question 12

what can a Vit. D deficiency lead to in children?

Answer 12

rickets

Question 13

what can a Vit. D deficiency lead to in adults?

Answer 13

Osteomalacia

Question 14

what is VDDR type 1?

Answer 14

Pseudovitamin D deficiency

Question 15

what causes VDDR type I

Answer 15

Defect in renal 25-OH-Vit. D 1-alpha hydroxylase

Question 16

Is 1,25(OH)2D3 high or low in VDDR type 1?

Answer 16

very low

Question 17

What causes VDDR type 2?

Answer 17

Defect in Vit. D receptor

Question 18

Is 1,25(OH)2D3 high or low in VDDR type 2?

Answer 18

High

Question 19

How do you treat primary hyperparathryoidism?

Answer 19

surgery

Question 20

Can inactivating mutations of CaSR cause familial primary hyperparathryoidism?

Answer 20

yes

Question 21

What occurs in this disease (hypercalcemia)?

Answer 21

Oversecretion of PTH due to hypocalcemia or decreased 1,25(OH)2D3
b. Renal failure

Question 22

what defines hypophosphatemia?

Answer 22

<2.5-4.5 mg/dL of Pi

Question 23

what is X-linked hypophosphatemic rickets (XLH)?

Answer 23

PHEX gene on X-chromosome gets mutated causing bone deformities

Question 24

what does PHEX normally do?

Answer 24

Inhibits FGF23 production

Question 25

what does XLH mutation do?

Answer 25

Causes inactive PHEX so FGF23 is increased

Question 26

How do you treat XLH?

Answer 26

. Phosphate supplementation b. High calcitriol

Question 27

What are the two forms of hypophosphatemic rickets?

Answer 27

Autosomal dominant b. Autosomal recessive

Question 28

What causes autosomal recessive hypophosphatemic rickets?

Answer 28

a.Mutations in DMP1 i. Causes overproduction of FGF23

Question 29

What causes hereditary hypophosphatemic rickets?

Answer 29

Loss of function mutations in NaPiIIc

Question 30

What is tumor induced osteomalacia?

Answer 30

An acquired syndrome of renal phosphate wasting

Question 31

What does the condition cause?

Answer 31

Secretion of factors into the blood like FGF23

Question 32

what defines hyperphosphatemia?

Answer 32

Phosphate > 4.5mg/dL or >1.5mM

Question 33

what are the symptoms of acute hyperphosphatemia?

Answer 33

Hypocalcemia

Question 34

what are the symptoms of chronic hyperphosphatemia?

Answer 34

Soft tissue calcification Renal failure

Question 36

What causes autosomal dominant hypophosphatemic rickets?

Answer 36

Mutations in FGF23 causing its increase

Question 37

How does renal failure cause hypercalcemia?

Answer 37

Due to the kidneys being unable to produce 1,25(OH)2D3 which inhibits PTH

Question 38

Is secondary hyperparathyroidism a condition of hypercalcemia?

Answer 38

no

Question 39

What causes hypercalcemia of malignancy?

Answer 39

Tumors that secrete factors that stimulate bone resorption

Question 40

What occurs to cause familial primary hyperparathryoidism in this instance?

Answer 40

CaSR inactive so high Ca levels are not sensed leading to elevated PTH since parathyroid gland reads Ca levels as low

Question 41

What occurs in MEN2A?

Answer 41

Gain of function mutation in RET protooncogene

Question 42

What occurs in MEN1?

Answer 42

Menin tumor suppressor gene inactivated

Question 43

What are the two types of familial primary hyperparathryoidism?

Answer 43

MEN1 (Mutiple Endocrine Neoplasia) b. MEN2A

Question 44

what can primary hyperparathyroidism cause?

Answer 44

Hypercalcemia Low Pi High bone turnover Kidney stones

Question 45

what causes primary hyperparathyroidism?

Answer 45

Oversecretion of PTH without a negative feedback on it

Question 46

what are the symptoms of hypercalcemia?

Answer 46

Fatigue EKG abnormalities Nausea, vomiting, constipation Anorexia Abdominal pain Hypercaciuria Calcification of soft tissues Hypercalcemic crisis

Question 47

what defines hypercalcemia?

Answer 47

Serum total calcium >10.5 mg/dL Ionized calcium >5.4 mg/dL

Question 48

What is VDDR type 2?

Answer 48

a. Hereditary vitamin D resistant rickets

Question 49

what are the two types of Vit. D deficient rickets?

Answer 49

Type 1 Type 2

Question 50

How does a lack of Vit. D inhibit Ca and Pi uptake?

Answer 50

Due to calcium transport proteins relying on Vit D to function, so without it they do not work

Question 51

What causes pseudohypoparathyroidism?

Answer 51

Hypocalcemia due to lack of sensitivity to PTH on tissues

Question 52

How can you treat hypoparathyroidism?

Answer 52

Calcium and calcitriol supplements