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Endocrine > 2-4-16-Regulation Of Ca And PO4 Metabolism (Lopez) > Flashcards

2-4-16-Regulation Of Ca And PO4 Metabolism (Lopez) Flashcards

1
Q

___ is twitching of the facial muscles elicited by tapping on facial n.

A

Chvostek sign

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2
Q

___ is carpopedal spasm upon inflation of a BP cuff

A

Trousseau sign

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3
Q

__ is characterized by a decreased QT interval, constipation, lack of appetite, polyuria, polydipsia, muscle weakness, hyporeflexia, lethargy, and coma

A

Hypercalcemia

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4
Q

___ reduces the activation threshold for Na channels –> easier to evoke an AP (less or no stimulus required to trigger an AP). THis results in increased membrane excitability and can produce numbness and tingling and muscle twitches

A

Hypocalcemia –> generation of spontaneous AP is the physical basis for hypocalcemic tetany

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5
Q

___ is characterized by decreased membrane excitability and the NS becomes depressed and reflex responses are slowed

A

Hypercalcemia

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6
Q

During ___, free ionized [Ca] increases because less Ca is bound to albumin

A

Acidemia –> leads to increased free ionized [Ca]; H+ kicks off the Ca2+ from albumin

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7
Q

During ___, free ionized [Ca] decreases, often accompanied by hypocalcemia

A

Alkalemia –> decreased ionized [Ca]; Ca stays on albumin since H+ does not displace it

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8
Q

Ca homeostasis is tightly regulated by these 3 organs ___ and these 3 hormones ___

A

Bones, kidneys, and intestine

PTH, calcitonin, Vit D

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9
Q

___ is an intracellular anion involved in the activation and deactivation of enzymes, as well as a buffer in bone, serum, and urine

A

PO4–> bone (85%), Plasma (

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10
Q

EC [Pi] is __ related to that of [Ca]

A

Inversely

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11
Q

The __ cells of the parathyroid glands synthesize and secrete PTH

A

Chief

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12
Q

What is the main stimulus for secretion of PTH?

A

Decreased plasma [Ca]

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13
Q

___ is characterized by long-term increased levels of plasma [Ca] and causes decreased synthesis and storage of PTH, increased breakdown of stored PTH and release of inactive PTH fragments into circulation

A

Chronic hypercalcemia

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14
Q

___ is characterized by long-term decreased plasma [Ca] and causes increased synthesis and storage of PTH, and hyperplasia of parathyroid glands (secondary hyperparathyroidism)

A

Chronic hypocalcemia

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15
Q

Severe hypomagnesemia can cause what?

A

Inhibition of PTH synthesis, storage, and secretion –> result of chronic Mg2+ depletion, as in alcoholism

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16
Q

PTH acts via this secondary messenger system___

A

Adenylate cyclase/cAMP

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17
Q

List the physiological affects of PTH on:

A-bone
B-Kidney
C-Intestine

A

A-Increased bone resorption
B-Decreased Pi reabsorption (phosphaturia), increased Ca reabsorption, increased urinary cAMP
C-Increased Ca reabsorption (via Vit D)

All will increase plasma [Ca] toward normal

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18
Q

__ promotes mineralization of new bone through its coordinated actions in the regulation of both Ca and Pi plasma concentrations

A

Vitamin D –> “steroid” hormone

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19
Q

In vitamin D synthesis, 7-dehydrocholesterol is converted to cholecalciferol via UV light. Cholecalciferol is then converted to 25-OH-cholecalciferol in the liver by this enzyme ___

A

25-hydroxylase

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20
Q

25-OH-cholecalciferol is converted to 1,25-(OH)2-cholecalciferol in the renal PCT by this enzyme ___

A

1-alpha-hydroxylase (CYP1alpha)

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21
Q

PTH receptors are located on these cells ___

A

Osteoblasts (not osteoclasts)

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22
Q

What are the short-term actions of PTH on bone?

What are the long-term actions of PTH on bone?

A

Short-term: Bone formation (via direct action on osteoblast) –> basis for use of intermittent synthetic PTH administration in osteoporosis treatment

Long-term: Increase bone resorption (indirect action on osteoclasts mediated by cytokines released from osteoblast)

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23
Q

___ acts synergistically with PTH to stimulate osteoclast activity and bone resorption

A

Vitamin D

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24
Q

In the formation and resorption in bone, ___ induces stem cells to differentiate into osteoclast precursors, mononuclear osteoclasts, and finally as mature multinucleated osteoclasts

A

M-CSF

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25
Q

___ is a cell surface protein produced by osteoblasts, bone lining cells, and apoptotic osteocytes. It is the primary mediator of osteoclast formation

A

RANKL (Receptor activator for NF-kB ligand)

26
Q

___ is a cell surface protein receptor on osteoclasts and osteoclast precursors

A

RANK

27
Q

___ is a soluble protein produced by osteoblasts, a decoy receptor for RANKL, inhibitor of RANK/RANKL interaction

A

Osteoprotegerin

28
Q

Osteoclast formation can occur via this ligand-receptor interaction ____

A

RANKL-RANK

Osteoprotegerin inhibits

29
Q

___ increases RANKL and decreased osteoprotegerin

___ increases RANKL

A

PTH

Vit D

30
Q

List the MOA of PTH on the kidney, specifically cells of the PCT

A

PTH binds its receptor on the basolateral membrane –> stimulates a Gs-Adenylate cyclase-cAMP 2nd messenger system –> activates protein kinase –>Phosphorylation–> inhibits Na-PO4 co-transporter to reabsorb both from the lumen (apical membrane)

31
Q

Inhibition of the Na-PO4 co-transporter on the apical membrane (lumen side) of the cells of the PCT causes ___

A

Phosphatria (increased excretion of Pi in urine)

32
Q

What are the actions of Vit D on the kidney?

A

Stimulates both Ca and Pi reabsorption

33
Q

In the SI, vitamin D increases Ca and Pi absorption by increasing ___ expression

A

Calbindin

34
Q

In the parathyroid gland, Vitamin D directly inhibits ___ expression and directly stimulates ___ expression

A

PTH gene

CaSR gene

35
Q

___ decreases blood Ca and Pi concentrations by inhibiting bone resorption. It decreases the activity and number of osteoclasts

A

Calcitonin –> major stimulus=increased plasma [Ca]

36
Q

A thyroidectomy will have what effect on calcitonin and Ca metabolism?

A thyroid tumor will have what effect on calcitonin and Ca metabolism?

A

Thyroidectomy –> decreased calcitonin, no effect on Ca metabolsim

Thyroid tumor –> increased calcitonin, no effect on Ca metabolism

37
Q

____ stimulates intestinal Ca absorption and renal tubular Ca reabsorption. It is also one of the most potent regulators of osteoblast and osteoclast function (promotes survival of osteoblasts and apoptosis of osteoclasts which favors bone formation)

A

Estradiol-17b

38
Q

___ promote bone resorption and renal Ca wasting and inhibit intestinal Ca absorption

A

Adrenal glucocorticoids (cortisol)

39
Q

In this disorder, pts excrete excessive amounts of Pi, cAMP, and Ca (Ca-oxalate stones).

A

Primary hyperparathyroidism –> “stone” “bones” and “groans” ; hypercalciuria (stones), increased bone resorption (bones), constipation (groans)

40
Q

What is a possible tx for primary hyperparathyroidism?

A

Parathyroidectomy

41
Q

List levels of PTH, Ca, Pi, and Vit D in primary hyperparathyroidism:

A

PTH=increased
Ca=Increased
Pi=Decreased
Vit D=Increased

42
Q

___ is characterized by increased PTH levels secondary to low [Ca] in blood. The low [Ca] can be caused by renal failure and vit D deficiency

A

Secondary hyperparathyroidism

43
Q

List levels of PTH, Ca, Pi, and Vit D in secondary hyperparathyroidism due to Renal failure

A

PTH=increased
Ca=decreased
Pi=Increased
Vit D=decreased

44
Q

List levels of PTH, Ca, Pi, and Vit D in secondary hyperparathyroidism due to Vit D deficiency

A

PTH=Increased

Ca, Pi, Vit D=all decreased

45
Q

___ can be caused by thyroid and/or parathyroid surgery or can be autoimmune. Most symptoms are associated with decreased Ca which can lead to muscle spasm or cramping, seizures, numbness, tingling, or burning

A

Hypoparathyroidism –> tx with oral Ca supplement and active form of Vit D

46
Q

List levels of PTH, Ca, Pi, and Vit D in Hypoparathyroidism

A

PTH=decreased
Ca=Decreased
Pi=Increased
Vit D=decreased

47
Q

__ is an inherited autosomal dominant disorder with a defect in Gs protein for both PTH in bone and the kidneys are defective. This leads to development of hypocalcemia and hyperphosphatemia. Phenotype includes short stature, short neck, obesity

A

Albright hereditary osteodystrophy (pseudohypoparathyroidism type 1a)

48
Q

List levels of PTH, Ca, Pi, and vit D for Albright hereditary Osteodystrophy (pseudohypoparathyroidism type 1a)

A

PTH=increased
Ca=Decreased
Pi=increased
Vit D=decreased

49
Q

What are some symptoms of hyperparathyroidism?

A 
Kidney stones
Osteoporosis
GI disturbances
Muscle weakness,
Depression
Polyuria
High serum [Ca], low serum [PO4]
50
Q

What are some symptoms of hypoparathyroidism?

A 
Tetany, convulsions, parasthesias, muscle cramps
Decreased myocardial contractility
1st degree heart block
CNS problems-irritability and psychosis
Intestinal malabsorption
Low serum [Ca]; high serum [PO4]
51
Q

___ is a disorder characterized by increased PTHrP levels and produces a similar profile to primary hyperparathyroidism such as increased urinary Ca, increased urinary Pi, cAmp as well as increased blood Ca and decreased blood Pi

A

Humoral hypercalcemia of malignancy

52
Q

___ is a peptide produced by tumors with close homology in the N-terminal to PTH

A

PTHrP –> binds and activates same receptor as PTH

53
Q

What is a tx for humoral hypercalcemia of malignancy?

A

Furosemide –> inhibits renal Ca reabsorption and increases Ca excretion

Etidronate –> inhibitor bone resorption

54
Q

List levels of PTH, Ca, Pi, and Vit D for humoral hypercalcemia of malignancy

A

PTH=decreased
Ca=Increased
Pi=decreased
Vit D=decreased

55
Q

__ is an autosomal dominant disorder caused by a mutation that inactivates CaSR in parathyroid glands and parallel Ca receptors in the ascending limb of the kidney. It results in decreased urinary Ca excretion (hypocalciuria) and increased serum [Ca] (hypercalcemia)

A

Familial Hypocalciuric Hypercalcemia (FHH)

56
Q

List PTH, Serum Ca, Urine Ca, Pi, and Vit levels for FHH

A 
PTH=increased
Serum Ca=increased
Urine Ca=decreased
Pi=N
Vit D=N
57
Q

___ occurs when there is an insufficient amount of Ca and Pi available to mineralize growing bone and characterized by growth failure and skeletal deformities. Most common in children

A

Rickets

58
Q

__ is when new bones fail to mineralize and characterized by bending and softening of weight-bearing bones

A

Osteomalacia

59
Q

List the deficit in Pseudovitamin D-deficient Rickets of Vitamin D-dependent rickets Type 1

List the deficity in Pseudovitamin D-deficient Rickets or Vitamin D-dependent Rickets Type 2

A

Type 1–> decreased 1-alpha-hydroxylase

Type 2–> decreased vitamin D receptor

60
Q

List PTH, Ca, Pi, urine, vit D levels and bone disturbances in the pathophysiology of Vitamin D

A 
PTH=Increased (secondary)
Ca=N/decreased
Pi=decreased
Urine=Increased Pi and increased cAMP
Vit D=decreased (primary disturbance)
Bone=osteomalacia, increased resorption
61
Q

List treatments for osteoporosis

A

Antiresorptive therapy –> biphosphonates, estrogen, Selective estrogen receptor modulators, calcitonin, RANKL inhibitors (Denosumab)

Anabolic therapy –> PTH

62
Q

__ is characterized by hyperreflexia, spontaneous twitching, muscle cramping, tingling and numbness, as well as + Chvostek sign and + Trousseau sign

A

Hypocalcemia –> decreased [Ca2+]

Endocrine (14 decks)

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