Calcium and Parathyroids Flashcards
Hyperparathyroidism is a disease of impaired _________
calcium
Too much PTH will move into the ______ cause destruction and results in _______ and ________
bones / osteoporosis / high serum calcium
What can high serum calcium levels cause?
increased BP, heart attack, stroke
Why is caclium important?
nerve conduction, bone formation, muscle formation, blood coagulation, cerebral and cardiac function, capillary permeability, cell growth and division, neurotransmitter action
The body contains __ to __ of calcium: __% in skeleton, ____% in plasma, ___% in ECF, __% in cells
1-2kg / 98% skeleton / 0.03% plasma / 0.1% ECF / 1% cells
Plasma calcium is present in the following forms
50% ionized (active form) / 41% protein bound (primarily to albumin) / 9% combined anions (diffusible)
Plasma calcium equilibrates with ____ calcium, but only 0.5% of _______ calcium is readily exchangeable
bone / bone
________ results in nervous system excitement. There is an increased neuronal permeability to _____, which results in easy action potentials
hypocalcema / Na
50% ionized or 35% total decrease leads to _____ _____
spontaneous discharges
Tetany and seizures from hypocaclemia are most commin in the _____ or ______
HAND or FACE
Hand and hypocaclemia
carpopedal spasm
Face and hypocaclemia
positive Chvosteks sign is from tapping on the facial nerve leads to twitching
In hypocalcemia, the ___ can be prolonged. What can this advance to?
QT / You can develop R on T phenomenon and advance to Torsades
The chief manifestation of hypercalcemia is ________
skeletal muscle weakness
Hypercalcemia can manifest as nervous system _______. This results in SHORT QT interval, LONG PR interval, constipation, anorexia
depression
Treatment for Hypercalcemia
maintain UOP, hydrate, administer MITHRAMYCIN in severe cases
The body contains ___ of phosphorous. __% skeletal, __% muscle/tissue, ___% ECF
1 kg / 85% skeletal, 15% musle/tissue, 1% ECF
Phsophorous circulates in plasma and about ___% is protein bound
12%
Phsophorous levels fluctuate more significantly than ______ because Phos moves between ECF and bone as well as ECF and ICF
calcium
T/F There are minimal effects with large fluctuations in phosphorus
TRUE
Phos enters the ECF via ___, ____, _____. It is easily absorbed in _____
GI, ICF, bone / GI
Phosphorous leaves via ____, ____, ____
urine, ICF, bone
Major control site for phos is the _______.
kidney
urinary excretion of Phos balances ____ uptake.
GI
PTH ______ urinary excretion of phos. So does calcitonin but to a lesser extent
increases
GI absorption of phos is increased by what vitamin?
1,25 D3
The parathyroid consists of 4 glands behind the ___ and ____ poles of the thyroid gland
upper and lower
The parathyroid contain mainly ____ cells and ______ cells
chief / oxyphil
**CHIEF cells secrete ________
PTH
**Synthesis and secretion of the PTH is related to _____ concentrations in the blood
calcium
Parathyroid glands can be enlarged from prolonged stimulation, _________ and _______
pregnancy and lactation
Decreases in calcium concentration in the ECF ______ secretion of PTH
increases
Increases in calcium concentration in the ECF ________ the activity of the parathyroid gland
decreases
Vit D, calcitonin, and PTH all help with reabsorption of calcium from the _____ ________ of the kidney
proximal tubule
PTH increases bone resorption to mobilize ____ and ______
calcium and phosphate
Bone resorption is the process by which _______ break down bone and release _______ from bone fluid to blood
osteoclasts / calcium
PTH increases reabsorption of calcium in the kidneys _______ tubules
distal
PTH decreases reabsorption of _______ in the renal tubule
phosphate
**PTH increases the production of 1,25 dihydroxycholecalciferol. This is a vit D metabolite which ______ intestinal Calcium absorption
enhances
**Major stimulus for PTH is what?
low serum calcium level
Increases in PTH results in what serum changes?
increased calcium and decreased phosphate
Increases inPTH results in what urine changes
decreased calcium and increased phosphate
Increases in PTH increases the ________ of phosphate, potassium, and sodium by increasing the CALCIUM/MAG/HYDROGEN _______. This happens largely where?
excretion / reabsorption / distal tubules and collecting ducts
**Calcitonin _______ the parathyroid hormone
opposes
**Calcitonin is produced in the ________ of the thyroid
parafollicular (clear or C cells)
In general, Calcitonin has the opposite effect of ____
PTH
Calcitonin inhibits bone _______. It increases ______excretion of calcium
resorption / urinary
Immediate effect of calcitonin is it _________ osteoclastic activity and osteolysis of osteocytes
decreases
Delayed effect of CALCITONIN is it _______ osteoclast formation
decreases
Calcitionin effect on serum
decreased calcium and decreased phosphate
Calcitonin effect on urine
increased calcium excretion and increased phosphate excretion
Secretion of Calcitonin is controlled by serum ______ level
calcium
Increased serum calcium level would lead to ________ calcitonin secretion
increased
T/F Exact role is unclear but excess or deficient calcitionin does not lead to defects in bone or calcium metabolism
TRUE
Vitamin D has a potent effect to increase calcium absorption from the _____ _____
intestinal tract
Vitamin D has important effects both on bone _____ and bone ______
depositation / reabsorption
** Vitamin D is not iteslf an active substance, but must be converted to its active product _________
1,25 dihydroxylcholecalciferol
**Vitamin ___ is formed in the skin by exposure to sunlight
D3
** Vitamin D3 is converted to 1,25 dihydroxylcholecalciferol in by the ______
liver
GI absorption of calcium is increased by _____
Vit D
Urinary excretion of calcium is decreased by ______ and increased by ________
PTH / Calcitonin
Bone resoprtion of calcium is increased by _____ and inhibited by _______
PTH / calcitionin
Hypoparathyroidism is usually a result of surgical damage to the gland during ______ surgery
thyroid
After thyroid surgery, calcium levels could fall below normal in 24-72 hrs which results in what?
Tetany (calcium ion interferes with membrane transport and interferes with the relaxation of the muscle), muscle cramps, Grand Mal seizures, cardiovascular collapse
Treatment for Hypoparathyroidism is what?
PTH (expensive and short half life) OR high calcium and Vit D intake
**Hypomagnesemia can cause hypocalcemia resistant to _______. So must treat with _______ first.
calcium / magensium
Magnesium suppresses the release of ____
PTH
Primary HYPERparahyroidism is from inappropriate hypersecretion of PTH resulting in ________.
hypercalcemia
Net effect of increased PTH secretion
hypercalcemia, hypercalciuria, HYPOphosphatemia, HYPERphosphaturia, bone demineralization
Net cardiac effects of increased PTH secretion
short QT interval, depresses relaxation
Net kidney effects of increased PTH secretion
kidney stone formation as calcium is mobilized from bone that is excreted by kidneys
Most common cause of hyperparathyroidism is _______ hyperplasia or _______ tumor
parathyroid / parathyroid
Pregnancy may ______ the parathyroids
stimulate
Vitamin D deficiency can be from inadequate dietary intake and often due to fat _______ syndrome. Can also be from inadequate sunlight
malabsorption
In Vitamin D deficiency you have decreased absoprtion of ______ and _______, decreased serum calcium and phosphate, and increased ____ and increased _______ resorption
calcium and phosphate / PTH and bone
In adults, Vitamin D deficiency can result in _______ or softening of the bones
osteomalacia
In children, Vitamin D deficiency can result in ______ - bones fail to mineralize, epiphysis fail to fuse, epiphyseal plates widen and bowing and fractures occur
Rickets
One gram of Calcium Chloride contains the equivalent amount of ionized calcium of what?
3 grams of Calcium gluconate
Calcium is indicated fro treatment of ______ induced EKG changes because of its cell membrane stabilizing effecs
HYPERKALEMIA
Calcium is indicated in patients with ________ associated with either CCB or beta-adrenergic blockers
hypotension
Calcium is contraindicated in patients with _______ toxicity as it may cause _______
digoxin / lethal arrhythmias