Bone Mineral Disorders (Pedia) Flashcards Preview

[OS 215] Exam 2 Cluster 1 > Bone Mineral Disorders (Pedia) > Flashcards

Flashcards in Bone Mineral Disorders (Pedia) Deck (27)
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1
Q

What percentage of body calcium is rapidly exchangable?

A

1%

2
Q

What percentage of serum calcium is bound?

A

40% is bound to albumin
10% is bound to citrate, lactate, bicarbonate, phosphate, and sulfate
50% is biologically active

3
Q

What are the “second messengers” involved in calcium transport?

A

cAMP, inositol, 1,4,5-triphosphate, and diacylglycerol

4
Q

What is the molecular “pore” through which calcium enters the cell

A

alpha subunit

5
Q

What are the functions of serum ionized calcium modulator?

A

signal transduction, cell to cell adhesion, clotting, muscular contraction, cardiac rhythmicity, enzyme action, synthesis and secretion of endocrine factors, cellular proliferation

6
Q

How does the kidney contribute to the regulation of iCa?

A

transcellular reabsorption of calcium in the distal convoluted tubules

7
Q

What portion of the PTH molecule binds to receptors in target organs?

A

amino terminus

8
Q

What is the net effect of PTH?

A
  1. increased serum calcium

2. decreased serum phosphorus

9
Q

What is the effect of calcitriol on intestinal absorption?

A

inc. absorption of calcium and phosphorus

10
Q

What is the net effect of calcitriol?

A

increased serum calcium and phosphorus

11
Q

Calcitonin is primarily secreted by?

A

parafollicular thyroid cells

12
Q

What portion of vitamin D synthesis occurs in the liver?

A

hydroxylation (product is calcidiol)

13
Q

Calcitonin is used as a marker for which type of malignancy?

A

medullary thyroid CA

14
Q

In hypocalcemia, what are the values of total serum and ionized Ca?

A

Total serum Ca < 7.5 mg/dL

Ionized Ca < 1.2 mmol/L

15
Q

What are the possible causes of pseudohypocalcemia?

A

hypoalbuminemia, alkalosis, elevated free fatty acids, lipid infusion, gadolinium contrast

16
Q

What is the Chvostek sign?

A

contraction of the orbicularis oris when the masseter muscle is tapped

17
Q

What is the Trosseau sign?

A

induced spasm when pressure is applied to the forearm

18
Q

What are the chronic Ssx of hypocalcemia?

A

calcification of basal ganglia, cataracts, rickets and osteomalacia

19
Q

What drugs can cause hypocalcemia?

A

biphosphanates, diuretics, citrate

20
Q

What are the causes of transient, abnormal PTH secretion?

A

hypomagnesemia, critical illness, pregnancy, toxicity

21
Q

What are the characteristic radiologic findings in hypocalcemic rickets?

A

widening and cupping of epiphyses, metaphyseal distortion from osteomalacia

22
Q

What are the 3 forms of hypocalcemic rickets?

A

nutritional deficiency, vitamin D-dependent, vitamin D-resistant

23
Q

What is pseudohypoparathyroidism?

A

resistance to PTH characterized by supranormal PTH levels

24
Q

What is the first-line treatment for hypocalcemia?

A

10% calcium gluconate (not over 2 ml/kg in 10 minutes)

25
Q

What are the maternal risk factors for neonatal hypocalcemia?

A

maternal diabetes mellitus and hyperparathyroidism, vitamin D or Mg deficiency

26
Q

What are the causes of hypercalcemia?

A

excessive PTH production, altered calcium sensing, excessive PTH receptor activity

27
Q

What are the treatments for severe hypercalcemia?

A

hydration, loop diuretics, hemodialysis, calcitonin, biphosphonates