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Therapeutics I > Block 4: Ca2+ and P > Flashcards

Block 4: Ca2+ and P Flashcards

1
Q

What is the function of Ca2+?

A
  1. Muscle contraction
  2. Membrane action potential
  3. Coagulation cascade
  4. Bone metabolism
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2
Q

Where is Ca2+ stored?

A
  1. Bone
  2. Serum
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3
Q

How is calcium regulated?

A

Vitamin D: carrier of Ca2+
Mg increases the absorption of Ca2+ (PTH)
PTH: ↑ Ca2+ → ↑ calcitonin →↓ Ca2+ absorption

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4
Q

How much of Ca2+ is in the body?

A

99% in bone
1% EC (40% is bound to albumin and rest is free calcium)

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5
Q

How do you calculate corrected calcium?

A

Corrected Calcium = Measured Ca + 0.8 (4- albumin)

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6
Q

What is normal serum total calcium?

A

8.4-10.2 mg/dL (2.1 to 2.55 mmol/L)

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7
Q

What is the normal serum ionized calcium?

A

4.48 to 5.32 mg/dL (1.12 to 1.33 mmol/L)

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8
Q

Describe the homeostasis of Ca2+

A
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9
Q

What is hypercalcemia?

A

> 10.2 mg/dL

Mild to moderate: 10.2 - 13 mg/dL
Severe: >13 mg/dL
Crisis: > 15 mg/dL

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10
Q

What are the causes of hypercalemia?

A
  1. Primary hyperPT
  2. Cancer secretions
  3. Immobilization
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11
Q

What drugs induce hypercalcemia?

A

Thiazides, Vit D, Lithium

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12
Q

What mechanisms are affected by hypercalcemia?

A
  1. Bone resorption (cancer, HPT)
  2. Increases calcium absorption in GIT (Vit D)
  3. Tubular reabsorption (thiazide, lithium)
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13
Q

What are the indications of mild to moderate Hyper calcemia?

A

<13
Asymptomatic
Drug induced or primary hyperparathyroidism

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14
Q

What are the indications of severe hypercalcemia (acute and chronic)?

A

> 13
Acute: N/V, constipation, polyuria, polydipsia
Chronic: calcification, nbephrolithiasis

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15
Q

What are the indications from hypercalcemic crisis?

A

> 15
AKI, Lethargy → chronic can lead to coma and life-threatening arrhythmias

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16
Q

Describe the treatment plan for hypercalcemia?

A
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17
Q

What is the first line for hypercalcemia?

A

0.9% NS
Loop diuretics

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18
Q

What are 1st lines for cancer associated hypercalcemia?

A

Pamidronate
Zoledronate

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19
Q

What should be used during refractory to bisphosphonate?

A

Denosumab (Xgeva not Prolia)

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20
Q

What is the function of calcitonin?

A

Inhibits bone resorption of Ca2+, inhibit absorption by intestine

Effectiveness can be increased if CS are added

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21
Q

CI of calcitonin? ADRs?

A

CHF, renal failure

Flushing, N/V, allergic reactions

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22
Q

What do you need to do prior to giving calcitonin?

A

10 units SQ test dose prior to starting therapy → continue with dosing if no erythema within 15 minutes

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23
Q

What is the MOA of bisphosphate?

A

Block bone resorption and inhibit osteoclast precursors

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24
Q

What are the first line for hypercalcemia caused by cancer?

A

Bisphosphates

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25
Types of bisphosphates and dosing?
Pamidronate 30-90 mg IV over 2-24 hr Zoledronic acid 4 mg IV over 15 minutes
26
ADR of using bisphosphates? CI? Warning?
ATN, jaw osteonecrosis Severe renal impairment requiring dosing mod Get dental work before use
27
What is the MOA of Denosumab? When should it be used?
Inhibitor principal mediator of osteoclast survival If bisphosphates don't work
28
ADR of Denosumab?
Jaw osteonecrosis, hungry bone, severe hypocalemiaW
29
How do the brands of denosumab differ?
Prolia (osteoporosis) Xgeva (hypercalcemia if bisphosphate failed)
30
What is the GC indication? MOA?
1. hypercalemia of myeloma, leukemia, lymphoma, sarcoidosis, combo with calcitonin Can prevent tachyphylaxis of salmon calcitonin Reduce GI absorption of calcium
31
ADRs of GC?
Hyperglycemia, osteoporosis, infection risk
32
How should GC be dosed for hypercalcemia?
Dosing: 200-400 mg HC equivalents IV daily, then pred 10-20 mg daily x 7 days
33
What is cinacalcet? Indication?
A calcimimetic that increases CaSr sensitivity resulting in lower PTH and serum Ca Primary/secondary hyperPT
34
How do you dose cinacalcet?
Titrate Q2-4w in 30 mg increments Max dose 90mg PO QID
35
What is the treatment of hypercalcemia in patients without heart or kidney impairment?
NS +/- loop diuretic for hydration and return to normal calcium level within 24-48 hr
36
What is the treatment of hypercalcemia in patients with renal and HF?
Hemodialysis Calcitonin ≥4 months: body can develop antibody → ↓ effect of calcitonin Add prednisone
37
What is the treatment of hypercalcemia in patients with primary/secondary hyperPT or parathyroid carcinoma?
1. Cinacalcet (PO) 2. Etelcalcetide (IV): for secondary (5 mg IV blood 3xwk at the end of dialysis
38
What is the treatment of hypercalcemia in cancer patients?
1. Bisphosphate: Pamidronate and zoledronic acid (more potent and better response) 2. Denosumab in refractory to bisphosphate (cost more)
39
What is hypocalcemia?
1. Serum <8.6 2. Ionized <4.4
40
What are the causes of hypocalcemia?
1. low PTH from Operations and Mg def 2. Vitamin D def 3. Drugs
41
What drugs cause hypocalcemia?
1. Sodium phosphate 2. Phenobarbital, phenytoin, ketoconazole (CYP3A4) 3. Furosemide 4. Calcitonin 5. Cinacalcet 6. Bisphosphate and denosumab
42
What are the the acute symptoms of hypocalcemia?
1. Tetany 2. Paresthesias 3. Seizure
43
What are the the chronic symptoms of hypocalcemia?
Depression and confusion
44
What are the the dermatologic symptoms of hypocalcemia?
Hairloss, grooved and brittle nails
45
What is the daily dose of elemental Ca?
1-3 g/day
46
What are the ADRs of PO calcium?
Constipation
47
What are the PO calcium salts and amount of elemental Ca?
Carbonate 40% Acetate 25% Citrate 21%
48
What are the IV Ca salts and mEq?
Chloride: 1g CaCl = 13.6 mEq Ca Gluconate: 1g of CaG = 4.6 mEQ Ca Preferred in alert patients
49
How often should IV calcium be monitored?
4-6 hrs
50
What is the hypocalcemia treatment if the corrected Ca <8.5 mg/dL
51
What is the hypocalcemia treatment is patient is symptomatic-acute with <7 Ca?
52
What is the function of phosphorus?
1. Source of ATP 2. Regulate cell metabolism 3. Bone and teeth health 4. Blood buffer system
53
How is phosphorus regulated?
PTH, FGF 23
54
Describe the homeostasis of phosphorus?
55
What are the normal values of phosphorus?
3-4.5 mg/dL
56
What is hyperphosphatemia? What are the causes?
>4.5 1. Renal failure 2. Tumor lysis 3. Hemolysis 4. Rhabdo 5. HypoPT 6. Acidosis
57
What are the presentations of hyperphosphatemia?
1. N/V 2. Lethargy 3. Seizures 4. EV calcifications 5. Nephrolithiasis 6. Hypocalcemia from low PTH 7. Red eye and pruritus (chronic)
58
Why does P increase when Ca decreases?
PTH compensates with lack of Ca by increasing P release
59
How do you treat hyperP in hypocalcemia patients?
IV calcium
60
How do you treat hyperP if norm or hyper calcemic?
Phosphate binders
61
How do you treat hyperP if symptomatic and failed other therapies?
Hemodialysis
62
What are the types of phosphate binders?
1. Calcium based (Carbonate and acetate) 2. Resins (Sevelamer HCl and carbonate) 3. iron based (ferric citrate and sucroferric oxyhydroxides) 4. Lanthanum carbonate
63
Out of the the iron based phosphate bind which ↑ Fe levels?
Ferric citrate Sucroferric oxyhydroxides doesn't effect Fe or Ca
64
What is the difference between phosphate binding resins?
Sevelamer HCl worsens acidosis Carbonate: basic
65
When should calcium based Phosphate binders not be used?
Hypercalcemia
66
What are the ADRs of phosphate binders?
1. Constipation 2. NVD 3. Hypercalcemia with Ca-based 4. Iron overload with ferric citrate
67
What is the max elemental Ca?
1500mg/day
68
How do you dose calcium carbonate?
1 tab (500mg) TID w/ meals (200 mg of elemental)
69
What are the counseling points of calcium carbonate?
1. Drug interactions with acid suppressors 2. Give prior to meals to increase solubility
70
How do you dose calcium acetate?
2 cap (667mg) PO TID with melas (169 of elemental)
71
How does calcium acetate differ from carbonate?
1. Bids 2x better to P 2. Less affected by gastric pH
72
What are the similarities of resin binders?
Initial Dose: 800 mg TID with meals Decreases LDL and ↑ HDL Cost the same
73
What is the difference between sevelamer HCl and carbonate?
HCl: risk of metabolic acidosis Carbonate comes in powder form
74
Dosing of ferric citrate? Counseling points?
2 tabs TID with meals Increases iron levels
75
How does sucroferric oxyhydrate differ from ferric citrate?
500 mg TID with meals 1. Chewable formatin 2. Lower pill burdern 3. Longer effects 4. Doesn't ↑ iron
76
How does lanthanum differ from other P binders?
Dosing: 500 mg TID with meals Chewable and powder formulations High binding capacity Poor GI absorption: localized Cost is higher
77
What are causes of hypophosphatemia?
1. Reduced GI absorption 2. Reduced tubular reabsorption 3. Cellular redistribution
78
What are causes of reduced GI absorption of P?
1. Alcholism 2. Diarrhea, anorexia 3. Phosphate binders
79
What are causes of reduced tubular reabsorption of P?
1. Diuretics, GC, sodium bicarbonate, ferric carboxymaltose 2. HyperPT
80
What are causes of cellular redistribution of P?
Refeeding Dextrose, glucagon, insulin, calciton
81
What are the presentations of hypophosphatemia?
1. Neuromuscular: weakness, paralysis (respiratory failure) 2. Rhabdomyolysis 3. Asymptomatic unless <1.5 mg/dL
82
What is hypophophatemia?
<2.7 mg/dL
83
What is referring syndrome?
84
When would IV P be used?
<1.5 or symptomatic Weight based: 0.32-0.64 mmol/kg
85
What are the salt forms of IV P?
Sodium phosphate 1mmol=4mEq Na Potassium phosphate 1mmol =4.4 mEq K
86
ADRs of IV P?
Ca/P product deposition, hypocalcemia
87
When is PO P used?
1.5-3 and asymptomatic
88
ADRs of PO P?
Diarrhea
89
What PO P is for high sodium and K levels?
K-Phos No2
90
What PO P is for low K levels?
Phos-NaK packet
91
What are the dangers of using Ca/P IV?
Cal (mEq/L) x Phosphate (mEq/L) > 55-60 results in precipitation and deposition of complexes in vasculature 1. Careful with admixtures 2. Less risk with gluconate
92

Therapeutics I (32 decks)

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