K, Ca, P, Mg Flashcards
98% of potassium is
Intracellular
What are normal serum levels of potassium
3.5-5.0 mEq/l
Where is the majority of K located in the body
Muscles»_space; bone, RBC, liver
Low K in cells can relate to what acid/base imbalance
Acidosis
What is normal plasma Ca
5.0 mEq/L
Where is most Ca stored
Bone
What does hypocalcemia do with neuromuscular excitability
Increases it
Leads to hypocalcemic tetany/spasticity
What does hypercalcemia do to neuromuscular excitability
Depresses activity
Threshold shifts away from resting membrane potential
What are the main regulators of Ca
PTH, calcitonin, calcitriol
Elevated serum calcium can be
Primary hyperparathyroidism and malignancy
Low serum calcium can be
Hypoparathyroidism, renal disease, or vitamin D deficiency
Most Pi is found
In bones
What is Pi levels related to
Levels of renal excretion
What are the 4 main regulators of Pi
Dietary, calcitriol, PTH, renal tubular
What does calcitriol do to Pi levels
Increased Pi resorption from bone and increased absorption from intestine
How does PTH affect Pi levels
Phosphorus resorption directly from bone and indirectly activates intestinal absorption through stimulation of calcitriol production
How does renal tubules affect Pi
Reabsorption of Pi, which is stimulated by tubular filtered load of Pi and inhibited by PTH
Where is most magnesium stored
50% in bone and 49% in ICF in muscle
What is Mg depletion associated with
Migraine, depression, epilepsy, SIDS, arrhythmia, preeclampsia, muscle cramps
What effect does PTH cause
Increase serum Ca and decrease serum Pi
Excess PTH can cause
Hypercalcemia, hypophosphatemia, hypercholermic metabolic acidosis
What stimulates calcitonin release
Hypercalcemia
What does calcitriol do
Increase serum Ca and Pi
Deficiency in calcitriol is thought to contribute to
Chronic pain
What does calcitonin do
Decreases serum Ca and Pi
