By Dawn Wolfgram, MD
As a patient with chronic kidney disease you are likely to hear a lot about albumin levels from your doctors, nurses, and dieticians. What albumin levels mean and why we monitor them may get confusing.
Albumin levels will mean different things depending on where they are measured. Having adequate albumin levels in your blood is a good thing but having albumin in your urine is a completely different matter. Hopefully this article can take some of the mystery out of albumin and help you understand why we monitor these levels.
Serum albumin, the albumin measured from your blood, has long been used as a market of nutritional status in all patients regardless of kidney function. Albumin is a protein which your body uses as a carrier for other substances such as electrolytes, hormones, and fatty acids. Albumin is also the main contributor to oncotic pressure, which means that it helps keep fluid in your blood vessel rather than allow it to leak into your tissues which causes swelling or edema.
Albumin is made up from amino acids, which are the building block of proteins. When you do not eat enough your body does not have the components it needs to make albumin and you can get low albumin levels (hypoalbuminemia) which can increase your risk for infections, and is associated with higher risk of mortality for patients on dialysis.
Another way that your albumin levels can be low is if you lose albumin through your urine. When your nephrologist says that you have protein in your urine (proteinuria) this means that your kidneys are losing albumin. Normal kidneys do not lose albumin, however if your kidneys are damaged then the filter system in the kidney does not work well and allows large protein such as albumin to seep through to the urine where it is lost. In diabetic patients the protein or albumin in the urine correlates with progressive decline in kidney function. To prevent protein in the urine you need to have good control of your blood pressure and glucose levels. There are specific medications which help prevent loss of protein through the urine.
So next time your nephrology team talks to you about your albumin levels pay attention to whether they are referring to your blood levels or urine levels. If your blood levels are low you can talk to a dietician about ways to increase your levels, and if your urine levels are high you can concentrate on blood pressure and glucose control along with making sure you are on the right medications. Make sure to ask questions and do what you can to keep your albumin in your blood and not in your urine.
Dr. Dawn Wolfgram is a first-year fellow. She attended medical school at the University of Wisconsin-Madison and completed her residency in Internal Medicine at the University of Michigan.
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