Calcium metabolism and lytes Flashcards
What % of calcium is bound to proteins like albumin?
~50%
Etiology of hypocalcemia
Can be due to hypoparathyroidism, vitamin D deficiency, hyperphosphatemia, malabsorption, acute pancreatitis, and renal disease.
The severity of clinical signs for hypocalcemia depend upon?
How rapidly levels fall.
What happens when the calcium levels fall?
neutonal membranes become increasingly more permeable to sodium, enhancing excitation. K & Mg ions have an antagonizing effect on this excitation.
Decreased myocardial contractility..
^PTH
S/S of hypocalcemia
Primarily d/t neuromuscular irritabiliy.
-tetany, mental irritability, muscle weakness, mental depression and anxiety. Prolonged Q-T interval.
Dx of hypocalcemia
Serum calium and ionized calcium.
Further testing required to determine cause of hypocalcemia.
H+ ___________ ionized Ca
increases
Alkalosis ________ ionized Ca
decreases
Hypercalcemia is defined as:
Total serum calcium > 12mg/dl
Ionized >1.42 mmol/L
Causes of hypercalemia
hypercalcemia of malignancy Primary hyperparathyroidism Osteolytic Granulomatous Hyper vit D secondary renay hyperPTH Addison's Idiopathic
Signs of hypercalcemia
Anorexia Vomiting Depression Weakness PU/PD dehyration Abdominal discomfort Constipation
Objectives of tx hypercalcemia
Correct dehydration
Promote calciuresis
Inhibit bone reabsorption
Treat underlying disorder
Causes of HYPOcalcemia
Primary hypoPTH Postpartum lactation Hyperphosphatemia (acute) Hypovitamin D Hypoalbuminemia
ER treatment of HYPOcalcemia
Calcium gluconate 10% - 0.5-1.5 ml/kg/IV over several minutes, monitor ECG during.
Maintain - 2ml/kg slowlt over 6-8hr. 5ml/kg slowly per 24hr.
Normal range for potassium
3.5-5.5 mEq/L
What are the 4 major categories of hypokalemia?
- Dilutional & decreased intake
- Transcellular maldistribution
- Loss via GIT
- Loss via urine
What is dilutional hypokalemia?
Usually acquired iatrogenically when given IV /SQ fluids that do now contain appropriate amounts of K+. Note: the 4 mEq/L of K+ in LRS is inadequate for maintenance and almost all maintenance fluids require K supplementation.
What is transcellular maldistribution hypokalemia?
A common cause is metabolic alkalosis, which allows transfer of K+ from ECF to the ICF in attempts to to correct alkalosis.
Hormones can cause similar shift (insulin, epi, and aldosterone).
How is hypokalemia caused by renal loss?
Many conditions can allow:
- high sodium intake
- alkalosis
- renal failure
- diuretics
- hyperaldosteronism
S/S of hypokalemia
Muscle weakness is primary sign.
May also see, lethargy, confusion, PU/PD, carb intolerance, ileus, and EKG changes.
When replacing potassium what is the rate it should be administered?
Should not exceed 0.5 mEq/kg/hr.
In extreme cases in patients with normal renal function up to 1.5 mEq/kg/hr can be given with close EGC monitoring.
What is an oral form of potassium supplementation?
Tumil K
S/S of HYPERkalemia
Muscle weakness due to deplorization.
Cardiac excitation and conduction abnormalities
What conduction abnormalities can be noted on an ECG from a hyperkalemia patient?
Loss of P waves.
High peaked or deep T waves, prolonged QRS complexes, complete heart block, bradycardia, atrial standstill, and ventricular fibrillation or standstill.
