Cardiac diagnostic tests and lab values

Question 1

BUN (blood urea nitrogen)

Answer 1

Range: 10-20 mg/dl

Purpose: BUN and creatinine are end products of protein metabolism excreted by the kidneys.

Elevated = reduced renal perfusion from decreased cardiac output or intravascular fluid volume deficit as a result of diuretic therapy or dehydration.

Question 2

Ca++ (Calcium)

Answer 2

Range: 8.6-10.2 mg/dL

Purpose:Calcium is necessary for blood coagulability, neuromuscular activity, and automaticity of the nodal cells (sinus and atrioventricular nodes).

Hypocalcemia: -slow nodal function -impairs myocardial contractility which increases the risk for heart failure.

Hypercalcemia: -occurs with the thiazide diuretics, these meds reduce renal excretion of calcium. -potentiates digitalis toxicity, causes increased myocardial contractility, and increases the risk for varying degrees of heart block and sudden death from ventricular fibrillation.