Calcium Flashcards
Calcium is essential for . . .
- cell membranes
- neuromuscular activity
- endocrine/exocrine secretory activities
- blood coagulation
- bone metabolism
99% of calcium is stored in the _____
bone
what is the normal range for total serum calcium?
8.5-10.5 mEq/L
What percentage of calcium is bound to albumin?
40%
ionized calcium is regulated by:
- PTH
- phos
- vit D
- calcitonin
What is the equation for corrected calcium?
[(4.0 - albumin) x 0.8] + Serum calcium
When a patient has metabolic ________, more calcium binds to albumin and there is less ionized calcium.
alkalosis
When a patient has metabolic ________, less calcium binds to albumin and there is more ionized calcium.
acidosis
How does PTH increases serum calcium?
increasing bone resorption
increasing renal retention of calcium
increasing renal excretion of phosphate
increasing renal formation of active vitamin D (which indirectly increases calcium absorption)
review pathophysiology bone notes!!
:)
How is hypocalcemia classified?
< 8.5 mg/dL
When are symptoms usually seen with hypocalcemia?
< 6.5 mg/dL
What are some causes of hypocalcemia?
Drug induced Low Mag Dietary deficiency alkalosis (less ionized calcium) hypoparathyroidism TLS (tumor lysis syndrome)
What are some drugs that can cause hypocalcemia?
diuretics (loops, acetazolamide), phenytoin, phenobarb, steroids, aminoglycosides, phosphate replacement products, bisphosphates
How does low mag cause low calcium?
it impairs PTH secretion and induces resistance at the organ level
(to fix this, just replace the magnesium)
Why does tumor lysis syndrome (TLS) cause low calcium?
when you decrease phosphorus, you decrease Ca2+
What is the clinical presentation of hypocalcemia?
tetany, muscle spasms anxiety, hallucinations hypotension, MI seizures, lethargy, stupor \+Trousseau's/Chvostek's sign
How do you treat hypocalcemia?
- treat life-threatening symptoms (CALCIUM 10% chloride or gluconate)
- Fix other electrolyte abnormalities (Mag)
- Correct Vitamin D deficiency
- Chronic hypocalcemia: give Calcium + Vit D products
usually 1-3 g daily elem calcium
What is the side effect of Calcium + D products?
constipation
How is hypercalcemia classified?
total serum calcium > 10.5 mg/dL
How is severe hypercalcemia classified?
> 13 mg/dL
What are some causes of hypercalcemia?
drug induced malignancy (lung or breast cancer) hyperparathyroidism TB sarcoidosis (allusive respiratory disease inflammatory problem breathing trouble usually treated with steroids) hyperthyroidism acidosis
What are some drugs that can cause hypercalcemia?
thiazide diuretics estrogens lithium vitamin A & D tamoxifen calcium supplements
how can hyperthyroidism cause hypercalcemia?
it can cause bones to breakdown which releases Ca2+ into the bloodstream
What is the clinical presentation of hypercalcemia?
mild-moderate hypercalcemia may be asymptomatic
severe (> 13 mg/dL)
• anorexia, N/V, constipation
• EKG changes: shortened QT interval, wide T wave
• Arrhythmias, bradycardia
What is the clinical presentation of hypercalcemia in a crisis state?
acute renal insufficiency
AMS
sudden death
What are some chronic complications caused by hypercalcemia?
- kidney stones
- calcification in organs
- acceleration of CAD
- calcification of arteries
Why can acute renal insufficiency occur due to hypercalcemia?
buildup of Ca2+ in tubules of nephron can lead to renal problems
How do you treat hypercalcemia?
- treat life-threatening complications
- reverse signs/symptoms, prevent complications
- normalize calcium
- treat underlying cause
fluids: NS at 200-300 mL/hr (higher rate than normal which is approx. 125 mL/h)
What are the 2 first line treatments for hypercalcemia?
- Fluids
2. Loops
Use caution when using a lot of fluid in what patients?
. . . .
What is the dose for furosemide given to treat hypercalcemia?
furosemide 40-80 mg IV q 1-4 h
How does furosemide treat hypercalcemia?
increases renal excretion of calcium and helps offset large amount of fluids
Fluids + Loops will decrease calcium by ___ to ___ mg/dL in 24 hours (pretty quick drop)
2-3
How do you treat hypercalcemia in renal failure patients?
hemodialysis
What are some other options for treating hypercalcemia caused by cancer?
bisphosphonates
others: last line– gallium nitrate, mithramycin
When using bisphosphonates, the calcium levels will decline in __ days and will hit the lowest point in ____ days.
2 days
7 days
What are some adverse drug effects caused by bisphosphonates?
fever
headache
nausea/volume
renal toxicity
When are bisphosphonates contraindicated?
when CrCl < 30 mL/min
How do bisphosphonates work?
decrease bone resorption (breakdown) which keeps serum Ca2+ from increasing
What are some drug names of bisphosphonates?
Pamidronate 30-90 mg IV over 2-24 h
Zolendronic acid 4 mg IV over 15 min
Ibandronate 2-4 mg IV over 2 hours
Oral bisphosphonates are usually used to treat _____________.
osteoporosis
What are some ADRs of oral bisphosphonates?
cause esophageal irritation, not great GI absorption
What is the dose of calcitonin?
4-8 units/kg SQ/IM q 12 h
How does calcitonin work?
Calcitonin is the shut off button or negative feedback product that is released when the Ca2+ level gets too high (can give as a drug to decrease Ca2+)
How is calcitonin usually given if the volume exceeds 2 mL?
IM
Calcitonin causes a rapid reduction in calcium, but . . .
it has an unpredictable duration (1-2 mg/dL)
Why should you test a small dose of calcitonin before giving it to patients?
because it is made from salmon and some people have a seafood allergy
Can the intranasal prep (Miacalcin) work to treat hypercalcemia?
NO
What are the last line agents to treat patients with hypercalcemia and cancer?
Gallium nitrate
Mithracmycin
What drugs do you use to treat chronic hypercalcemia?
Steroids • slow onset • prednisone 40-60 mg daily (HIGH dose) Cinacalcet (Sensipar) 30 mg po BID • specifically used in pts with secondary hyperparathyroidism (CKD)
