Class 3 Calcium and Parathyroid Flashcards
Body contains how much calcium and where is it found?
- 1-2 kg
- 98% in skeleton, 1% cells, 0.1 ECF, 0.03 plasma
Plasma forms
- 50% ionized (active)
- 41% protein bound
- 9% combined w/ anions
What is seen with hypocalcemia? And whaen is it seen?
- Nervous system excitement r/t permeability of Na which leads to easy action potentials
- 50% ion loss or 35% total ca loss
What type of nervous system problems are seen with hypocalcemia?
- Tetany
- —Hands and face
- Seizures
- Long QT
Hypercalcemia leads to what?
- Skeletal muscle weakness
- Nervous system depression
Nervous system depression seen in hypercalcemia does what?
- Short QT
- Long PR
- Constipation
- Anorexia
How to treat hypercalcemia?
- Maintain UOP
- Hydrate
- Mithramycin
How much phosphorus is in the body?
- 1 kg
- 85% in skeleton, 15% muscle, 1% ECF
What levels fluctuate more, calcium of phos and why?
-Phos, moves between ECF and Bone , and ECF and ICF
Where is the major control site of phosphorus?
- Kidney
- Urinary excretion balances GI intake
What increases phos urinary excretion?
-PTH and calcitonin
Describe the parathyroid?
- 4 small glands on the thyroid
- Mainly chief and oxyphil cells
What do chief cells secrete?
-parathyroid hormone (PTH)
PTH synthesis and secretion is related to what?
- blood calcium levels in the ECF
- ↓ Ca = ↑ PTH
- ↑ Ca = ↓ PTH
What can enlarge the parathyroid glands?
- Prolonged stimulation
- Pregnancy
- Lactation
What 4 things are involved with calcium homeostasis? and where do they work?
- PTH
- Vitamin D
- Calcitonin
- Reabsorption of Ca in the proximal tubules
What is the major stimulus of PTH, and what 4 things does it PTH do?
- Low serum Ca levels
- increase bone resorption
- Increase reabsorption of Ca in the distal tubules
- Decrease phos reabsorption
- Increase production of 1,25-dihydroxycholecalciferol
what does 1,25-dihydroxycholecalciferol do?
-Vitamin D metabolite enhances intestinal Ca absorption
What do you see with Increases in PTH with Serum? Urine?
- Serum = Increased Ca & decreased Phos
- Urine = Decreased Ca & increased phos
What opposes the effect of PTH and where is it made?
- Calcitonin
- Parafollicular (clear) cells of the thyroid
How does calcitonin decrease calcium?
- Inhibit bone resorption
- Increases urinary excretion of Ca
Increased levels of calcitonin would show what in serum and urine?
- Serum = Decreased Ca and Phos
- Urine = increased Ca and phos
How does Vitamin D effect calcium?
-increase Ca absorption from GI
How does Vitamin D work?
- Formed in skin by sunlight
- Converted to 1,25-dihydroxycholecalciferol in liver to work
Hypoparathyroidism results in what? and leads to what?
- Low calcium levels
- Tetany
- Muscle cramps
- Grand mal seizures
- CV collapse
How is hypoparathyroidism treated?
- PTH
- High calcium and Vit D
When mag causes the hypocalcemia what must be done 1st?
- 1st treat Mag
- Mag can suppress PTH
How does hypercalcemia effect cardiac function?
- Shortens QT**
- Depresses relaxation
Effects of hyperparathyroid on kidneys?
-kidney Stone formation
What are the most common causes of hyperparathyroid?
- parathyroid hyperplasia**
- Parathyroid tumor **
Pregnancy may stimulate what?
-Parathyroids
What is secondary hyperparathyroidism?
-hypersecretion of PTH in response to hypocalcemic stress (Vit D defficiency or chronic renal disease)
Secondary hyperparathyroidism results in what?
-Osteomalacia (softening of bones)
Causes of Vitamin D deficiency?
- Inadequate dietary intake (fat malabsorption)
- Inadequate sunlight
Vitamin D results in what for adults? Children
- Adults = osteomalacia
- Children = Rickets
One gram of calcium chloride = ____ grams of calcium gluconate
-3
Why is calcium indicated in hyperkalemic EKG changes?
-Cell membrane stabilizing effects
Calcium is indicated for hypotension caused by what 2 drugs?
- Calcium channel blockers
- Beta blockers
Calcium is indicated for magnesium toxicity for patients being treated for what?
Preeclampsia
What is calcium contraindicated for and why?
- Digoxin toxicity
- Lethal arrhythmias
