Parathyroid Flashcards
How much Ca is in plasma? Of those how much is ionized?
0.03% in plasma, 0.1% in ECF, 98% in bone
50% ionized, 41% proteins bound, 9% combined with anions
Only 0.5% of bone calcium are readily exchangeable. The rest is slowly exchangeable.
Why is calcium important?
Nerve conduction Bone formation Muscle functions Blood coag Cerebral and cardiac fx Cap permeability Cell growth and division Neurotransmitter action
Effects of hypocalcemia
Tx of hypoparathyroidism?0
NS excitability:
Tetany, sz, Chvostek sign,
Longer QT
Increased sodium permeability -> trigger easily
50% ion/35% total decrease lead to spont discharge
Ca and vit D suppl
Effects of hypercalcemia
Tx in severe case?
Skeletal weakness
Nervous depression
Short QT, long PR, anorexia, constipation
Tx: mithramycin in severe case
T/F: phos moves b/t ECF & bone and b/t ECF & ICF easily
True
T/F: major control site of phos is kidney
True
T/F: Phos enter ECF via GI, ICF, bone and leave via urine, ICF, bone
True
What cells secrete PTH? When?
Chief cells
When calcium concentration in ECF decrease
How does PTH increase [Ca]?
By
- Increase bone resorption/break down (also release phos)
- Increase production of cholecalciferol, active form of vit D (enhance GI absorption of calcium)
- Hold in to Ca and red rid of Phos via kidney
Where is calcitonin produced? What is its effect?
Para follicular of thyroid
Decrease calcium
Increase renal Ca and Phos excretion
Which organ convert cholecalciferol (inactive vit D) into its active form?
Liver
T/F
Pregnancy can stimulate parathyroid
True
What can vit D deficiency cause?
Dec’d absorption of Ca and Phos, dec’d serum Ca and Phos, inc’d PTH and inc’d bone resorption
Adult: osteomalacia
Children: Rickets
Indication for calcium therapy?
- HyperK induced EKG changes due to its membrane stability effects
- Hypotension asso with Ca and beta blockers
- Magnesium toxicity as in preeclampsia tx
