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Endocrine > Pathophysiology of Calcium Metabolism & Bone Disease > Flashcards

Pathophysiology of Calcium Metabolism & Bone Disease Flashcards

1
Q

Excess vitamin D can lead to what endocrine disorder?

A

Hypoparathyroidism - excess vitamin D elevates Ca2+ and suppressed PTH

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2
Q

What is the most common cause of secondary hyperparathyroidism?

A

Chronic renal failure - low calcium leads to increased PTH secretion

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3
Q

What laboratory findings would be likely in a patient with primary hyperparathyroidism?

A

Elevated PTH, elevated Ca2+, elevated cAMP, decreased phosphate

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4
Q

This is a less severe form of osteoporosis characterized by decreased bone mass, without increased feature risk.

A

Osteopenia

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5
Q

What is generally the first clinical sign of osteoporosis?

A

Decreased height

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6
Q

What is the normal plasma calcium levels?

A

8.5-10.5 mg/dL

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7
Q

What laboratory results would be expected in a patient with secondary hyperparathyroidism?

A

Decreased Ca2+, elevated phosphate, elevated PTH

Vitamin D may also be decreased in severe cases

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8
Q

Increased levels of alkaline phosphatase are indicative of what bone process?

A

Osteoblast activity (bone formation)

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9
Q

What is the inciting factor in cases of tertiary hyperparathyroidism?

A

Prolonged secondary hyperparathyroidism causing hyperplasia of the parathyroid

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10
Q

What molecule is excreted in higher levels in the urine during periods of bone resorption?

A

Hydroxyproline

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11
Q

These cytokines are produced by osteoblasts and promote development of mature osteoclasts.

A

Macrophage-colony stimulating factor (M-CSF) & IL-6

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12
Q

Patients with this disorder require higher than normal Ca2+ levels to suppress PTH secretion by the parathyroid. What mutation is associated with the disorder?

A

Familial Hypocalciuric Hypercalcemia (FHH) - loss of function mutation in CaSR gene

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13
Q

Bisphosphonates treat hypercalcemia, but take a few days to reach maximum effect. What rapid-acting drug is given as a bridge therapy?

A

Cinacalcet

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14
Q

What is the most widely used test for osteoporosis?

A

Fracture Risk Assessment Tool (FRAX)

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15
Q

What is the most common cause of primary hypoparathyroidism?

A

Surgical excision of the gland

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16
Q

What are the stages of Paget Disease?

A

Lytic phase - increased osteoclast activity

Sclerotic phase - increased osteoblast activity

Quiescent phase - reduced activity

17
Q

How are osteocytes activated by osteoblasts?

A

Osteoblasts secrete RANK-L, which binds to RANK receptors on osteocytes and activates them

18
Q

Estrogen protects against bone resorption. How?

A

Estrogen promotes secretion of osteoprotegerin (OPG), which is a decoy receptor for RANK-L, thus preventing osteocyte activation

19
Q

This is the pediatric form of osteomalacia due to vitamin D deficiency.

A

Rickets

20
Q

These are mature bone cells that regulate bone resorption and formation.

A

Osteocytes

21
Q

This bone disorder is characterized by increased bone density due to failure of bone resorption.

A

Osteopetrosis

22
Q

What are the most common causes of primary osteoporosis?

A

Postmenopausal & senile

23
Q

What disorder is associated with a gain of function mutation in the CaSR gene?

A

Hypoparathyroidism - lower levels of Ca2+ suppress PTH leading to hypocalcemia

24
Q

What is the most common clinical presentation of patients with primary hyperparathyroidism?

A

Asymptomatic - symptoms that do present are due to the associated hypercalcemia

25
Q

What is pseudohypoparathyroidism and expected lab results?

A

PTH is secreted, but target tissues do not respond due to defective G proteins.

Lab results would include decreased Ca2+, increased phosphate, and normal or increased PTH

26
Q

What is Paget Disease?

A

A disorder of bone remodeling in which osteoclasts and osteoblasts are hyperactive. This leads to thickened, but weak bones.

27
Q

What is the most common cause of primary hyperparathyroidism?

A

Solitary parathyroid adenoma

28
Q

A patient presents with weight loss, nausea, vomiting, and muscle weakness. Lab tests reveal elevated Ca2+, decreased phosphate, and decreased PTH. What is the likely diagnosis?

A

Hypercalcemia of malignancy

Decreased PTH with elevated Ca2+ is highly suggestive of malignancy

29
Q

What is the cause of osteomalacia and rickets?

A

Decreased Vitamin D

30
Q

What is the most common located for osteonecrosis?

A

Femoral head

31
Q

These cells synthesize, transport, and lay down organic bone matrix.

A

Osteoblasts

32
Q

True/False. Osteoblasts and osteocytes are simultaneously active leading to a dynamic process of bone resorption and deposition.

A

True

33
Q

This bone disorder is characterized by decreased bone mass and increased fracture risk.

A

Osteoporosis

Endocrine (15 decks)

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