Kidney Disease: Understanding Your Lab Values



hi welcome to a chronic kidney disease program at University of California San Diego my name is Dan Otis Redding Eska and I'm a nephrologist in our clinic in this module we'll talk about laboratory values for chronic kidney disease it is important that you track and understand your lab values we already talked about creating in the previous module creatinine is a waste product from the muscle which is normally removed by the kidneys the level in the blood rises when kidneys do not function well GFR or glomerular filtration rate is calculated based on your creatinine and it estimates percent of normal kidney function blood urea nitrogen also known as B UN or some patients like to call it bun it's a waste product from dietary protein which is removed by the kidneys B UN or bun is also used to estimate the level of kidney function but it is less reliable than creatinine it can be affected by how much fluid one drinks and some other variables so we prefer to focus more on creating let's move on to electrolytes and acid-base balance in the blood most people know that too much sodium is not good for you unfortunately the level of sodium in the blood does not reflect how much sodium you're eating you might be eating three times as much as you should as an average American does yet your measured level will remain normal at the expense of drinking more fluid to dilute this extra sodium and possibly elevating your blood pressure and putting extra strain on your heart some people can however develop abnormal level of sodium in the blood due to either poorly functioning heart or kidneys or liver or some hormonal disturbances normal level of sodium is between 135 and 145 potassium is a mineral in your blood that helps your heart and muscles work properly if the level is too high it can change your heartbeat and lead to potentially dangerous arrhythmia normal range is between three point five to five point one if potassium level in your blood gets to be too high we'll educate you how to avoid foods which are high in potassium and use medications to help maintain healthy potassium level now bicarbonate bicarbonate is a measure of acidity of your blood patients with chronic kidney disease often cannot excrete acid generated from metabolism of foods that they ingest mainly it comes from protein and they develop metabolic acidosis so what metabolic acidosis big deal right well it is a big deal metabolic acidosis also known as too much acid or too little base can lead to muscle breakdown no one wants to have weak muscle right it can also lead to weak bones and it can speed up the progression of chronic kidney disease normal value for bicarbonate is between 22 and 29 if your level is below that your nephrologist might prescribe baking soda or similar type of medication to correct it to neutralize extra acid in your body and thus protect your muscle protect your bones and slow down the progression of chronic kidney disease the next three laboratory values have to do with bone health they can be are adversely affected by kidney disease and lead to weak bones calcium and phosphorus are important for strong bones up normal levels of calcium and phosphorus besides leading to bone disease believe it or not they can get deposited in your blood vessels heart and other organs and cause damage as well normal levels for those minerals might slightly vary depending on the laboratory but usually our eight point six to ten point five milligrams per deciliter for calcium and two point seven to four point five for phosphorus we will help you maintain normal calcium and normal phosphorus levels with appropriate diet and if needed we use some medications now parathyroid hormone also known as PTH and not to be confused with thyroid hormone or TSH this is something different so PTH regulates movement of calcium and phosphorus between your blood bones and also affects the excretion in the urine the acceptable level for PTH depends on the stage of kidney disease so you will have to check with your doctor what's the appropriate level for you if your PTH gets to be too high will prescribe special type of vitamin D which will bring it down to more healthy levels we are moving on now to laboratory values for anaemia hemoglobin is part of red blood cells that carries oxygen from your lungs to all parts of the body hemoglobin is used to diagnose anemia the target range for hemoglobin in patients with CKD is somewhere between nine point five to eleven and it's kind of a moving target but for now this is what it is if your hemoglobin level is below this range your doctorate might prescribe special medication that will help you your body produce more blood we also periodically measure your iron stores iron stores are very important iron is a necessary building block for red blood cells should you be iron deficient your doctor will likely prescribe either iron pills or intravenous infusion to correct this deficiency let's talk about cholesterol for a moment everyone knows about cholesterol right cholesterol is a fat like substance that is found in all cells of the body your body certainly needs some cholesterol but if present in excess it can lead to heart disease normal cholesterol level is considered to be under 200 there are two basic types of cholesterol HDL also known as good cholesterol you get a smiley face for this it has protective properties to the heart so you want this number pretty high one of the ways to increase HDL is by exercise and we'll talk about this more LDL also known as bad cholesterol does not get a smiley face it can contribute to heart disease so you want this number on a lower side your doctor might ask you to take cholesterol medication even if your level of cholesterol is under 200 so normal right there is the reason is that patients with CKD are at high risk for heart disease regardless of cholesterol level as I mentioned in the previous module protecting your heart is our number-one priority yes we're kidney doctors yes we care about kidneys but heart comes first a triglyceride is another type of fat found in your blood and if elevated it might increase your risk of heart disease it's usually measured at the same time as measure cholesterol we are now down going over various blood tests and are ready to focus on testing of the urine in the normal state of kidney health there should be no blood no protein and no bacteria in the urine nothing like that presence of blood or protein cannot be detected with a naked eye that's why we asked you to submit urine sample to the lab for a more precise microscopic measurements if your kidneys are spilling protein in the urine we'll run an extra test to quantify how much protein is being wasted protein in the urine also known as proteinuria if you want to sound like a nephrologist can overtime cause damage to your kidneys whenever possible we use medications to decrease the amount of protein in the urine and to protect your kidneys besides checking blood and urine tests your nephrologist will likely want to have a picture of your kidneys this is done to make sure that you have two kidneys yes some people are born with just one kidney and they don't know about this it's an incidental finding and we also want to make sure that there is no obstruction or abnormal cysts in your kidneys depending on your situation your you might be asked to do either a kidney ultrasound which is pretty simple or a little bit more sophisticated tests like cat scan or even MRI let's do two questions to test your understanding of this module question number one what blood tests do we use to estimate level of kidney function or GFR is it a sodium or B potassium or C creatine or D phosphorus all right let's think about this for a second and the correct answer is C or creatinine creatinine is use to calculate GFR all right are you guys ready for question number two how much protein should be present in the urine option a none option B some but not too much and let's see option C the more the better all right which one is it okay and the correct answer is that there should be absolutely no protein in the urine protein in the urine is a risk factor for worsening kidney function over time we do everything we can to minimize the amount of protein in the urine congratulations you have completed the module on laboratory values for chronic kidney disease please check our website for additional educational modules on kidney health

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