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65 Cards in this Set

  • Front
  • Back
Parathyroid hormone
-Polypeptide made by parathyroid gland
-Released in response to decreased plasma calcium
-Causes increased calcium and phosphate mobilization from bone
PTH effect on osteoblasts and osteoclasts
Increased number of osteoblasts and osteoclasts which causes calcium mobilization
PTH effects on kidney
Decrease ca and increasd phosphate excretion

Increased activation of Vitamin D
Active Vitamin D
1,25 dihydroxyvitamin D
PTH affect on GI tract
Vitamin D activation, which indirectly increases calcium absorption
Two forms of vitamin D
Synthesis of Vitamin D
Formed from cholesterol by 7-dehydrocholesterol enzyme, along with UV radiation
Most active form of vitamin D

1,25 dihydroxyvitamin D
Activation of Vitamin D
Requires Liver (25 hydroxyvitaminD) and kidney (1,25)

Kidney is rate limiting step

Activation in kidney is increased with PTH, low plasma ca and phosphate
Estrogen Effects on calcium homeostasis
Preserves calcium in bone (unknown mechanism)
Glucocortoid effects on calcium homeostasis
At pharmacological levels (not physiological levels) it increases calcium resorption from bone
-Polypeptide produced in thyroid
-Not vital to Calcium homeostasis
-Modulates Vitamin D and PTH regulation
-Released in response to increased plasma calcium
Calcitonin's effects on bone
Direct inhibition of osteoclast activity-> decreased bone resorption

-may stimulate osteoblast formation
Calcitonin's effects on Kidney
Increases calcium, phosphate, and other ion excretion
Net result of Calcitonin releases
Tones down serum calcium (and phosphate)
Is PTH orally available
NO, It's a polypeptide

-low oral availability
-Rapid metabolism in KIDNEY and liver
PTH administration
Must be by injection (parenteral)
PTH Mechanism of Action
Increases osteoblast number->increases plasma calcium levels
PTH indications
Adverse affects of PTH

(uncommon at low dose used)
Contraindications of PTH use
Use with diphoshonates
Is Calcitonin orally available?
NO, It's a polypeptide

-low oral availability
-Rapid metabolism
Calcitonin Mechanism of action
-increases excretion of calcium and phosphate (and sodium, Mg, Cl)
-Decreases activity of osteoclasts->decreased bone resorption

-Decreases plasma calcium levels
Calcitonin half life
Very short T1/2, but salmon ct has longer halflife

metabolized in liver and kidney
indications for Calcitonin
Pagets Disease

To decrease Ca loss from bone and bone turnover

Hypercalcemia of malignancy
Adverse effects of Calcitonin
Hypocalcemia, uncommon due to escape of calcitonin in kidney
Vitamin D
pro-drug that must by activatied by 2 steps of hydroxylation 25-liver, 1-kidney
25 hydroxyvitamin D

Converted to calcitriol in a HEALTHY KIDNEY
Most active vitamin D

1, 25 dihydroxy vitamin D
Dihydrotachysterol (DHT)
Reduced form of Vitamin D2, activated by 25 hydroxylation in liver

useful in renal disease because it doesn't need a kidney
Mechanism of action of Vitamin D
Increased plasma calcium by
-increasing absorption through the gut and bone deposition
-increased release of Calcium from bone
-Decreased excretion from kidneys
Vitamin D bioavailability?
Yes-Readily absorpbed by gut IF bile salts present

-imparied absorption with biliary cirhosis, steatorrhea
Vitamin D half-life and excretion
-T1/2 1-3 days, but it's stored in body tissues for long periods
-Excreted in Bile
Therapeutic Uses of Vitamin D
-Rickets and osteomalacia
-Renal Failure
Adverse effects of Vitamin D
Contraindications of Vitamin D use
Impaired renal function

(inc risk of hypercalcemia)
Calcium salts indications
-renal failure
-intestinal osteodystrophy
Adverse Effects Calcium Salts
Drug interactions Calcium Salts
Thiazide Diuretics (dec calcium excretion)->HYPERCALCEMIA

When given IV, it can precipitate salts

-Digoxin sensitizes heart to Calcium, so Calcium Salts cause wierd, severe heart problems
Diphosphonate Etidronate


-Analouge to Pyrophosphate
-Deacreases osteoclast activity and number->slows bone turnover
Diphosphonate Etidronate


Use for osteoporosis (treatment and prophylaxis)

Hypercalcemia of Malignancy
Diphosphonate Etidronate


Oral or IV
Diphosphonate Etidronate

Adverse Effects
Decreased bone mineralization can lead to OSTEOMALACIA and BONE PAIN
PTH effectiveness with or without Diphosphonates
PTH alone is more effective than pth and diphosphonates together
Selective Estrogen Receptor Modulators (SERMS) For?
Women lacking estrogen who have increased bone resoprtion

-post hysterectomy
eg Raloxifene
Estrogen agonist activity (full or partial) at bone and Cardiovascular tissues

antagonist activity ot other organs (uterine and breast)
Loop Diuretics and Calcium
Decreased calcium reabsorption (->increasd excretion)

Used for hypercalcemia
Thiazide diuretics and calcium
Increasd Calcium reabsorption
->decreased excretion

Used in hypercalCEURIA (ie stones)
Causes of hypercalcemia
-hypervitaminosis D
-Malignancies sometimes

Treatment for hypercalcemia
-Diphosphonates (chronic)
-Calcitonin (chronic)
-Loop Diuretics (acute)
Treatment of HyperCALCIURIA
Thiazide Diuretics
Causes of HYPOcalcemia
-Rickets(juv) and Osteomalacia(adult)
-Renal Failure
Rickets and osteomalacia due to?
Vitamin D deficiency
Lack of activation or resistance to Vitamin D
calcium malabsorption
Treatment for hypocalcemia
Vitamin D (or active analogs) and calcium supplements
Excessive resorption of calcium (and loss of bone)
Caused by aging, decreased estrogen (androgen?) and excess GC levels
osteoporosis treatment
Vitamin D, Dietary Calcium, diphosphonate, calcitonin, PTH, SERMs (women only)
Pagets disease causes
-excessive formation and resportion of bone
-abnormal mutinucleated osteoclasts
-pagetic bone (thick and abn)
-Also causes Deafness, spinal cord compression, High output heart failure, pain
Pagets Disease Treatment
Calcitonin, Diphosphonates to decrease bone mineralization
Uses for Vitmin D
Rickets, osteomalacia, hypocalcemia, hypoparathyroidism, osteoporosis, renal failure/disease
uses for PTH
Uses for calcitonin
Pagets Disease
hypercalcemia of malignancy
Uses for SERMs or Estrogen
Uses of Diphosphonates
Osteoporosis, pagets disease, hypercalcemia
Uses of Loop diuretics
Uses of thazide diuretics