you need to consider the elevated bun as one of the patient's symptoms and look at what this means in relation to other pathophysiology going on with this patient in determining your nursing problems. you can find information about what a bun is in a lab reference book and on certain internet websites if you do not have a lab reference book: urea is an end product of protein metabolism formed in the liver and is excreted by the kidneys. the bun is a reflection of the amount of urea being produced by the liver and the amount of urea being excreted by the kidneys. it should be evaluated along with the creatinine level to get a better picture of the situation that is going on. the bun levels can change rapidly from day to day and reflect the body's situation on a daily basis; the creatinine levels are related to a person's muscle mass so change in creatinine levels take longer to appear. mosby's diagnostic and laboratory test reference, 4th edition, says that
this test is "directly related to the metabolic function of the liver and the excretory function of the kidney. . .[and]. . .serves as a index of the function of those organs" (page 857). however, it also says that the bun can elevate in conditions other than primary renal disease, especially when large amounts of protein are available to be processed. with increased protein metabolism larger amounts of urea will be made (e.g. high protein diets, starvation, massive tissue trauma, gi bleeding). and, keep in mind that urea, which is what the bun test measures, is made by the liver. so, when there are low buns there may be liver failure.
there actually can be some presenting symptoms of grossly
elevated urea levels: acidemia, agitation, confusion, fatigue, nausea, vomiting and coma. interventions would include treatment of the underlying cause, giving iv bicarbonate, low protein diet, hemodialysis and avoiding nephrotoxic medication (page 1314, davis's comprehensive handbook of laboratory and diagnostic tests with nursing implications, 2nd edition
chf is one of the conditions where the bun may become elevated. the reason is because of decreased renal perfusion as a result of the heart failure. make sure you read about the pathophysiology of heart failure and how the heart muscle is failing to perform its job. that affects the remainder of the body systems, particularly if the heart isn't pumping efficiently so that perfusion to other body organs is below par. it may also be because of the side effect of diuretics or ace inhibitors that the patient is on. or, the patient may be showing early signs of renal failure (look at the creatinine level).
a lot to consider, isn't it?