This week, Senior Underwriter, Elliott Dickson explores abnormal kidney functions in younger ages.
Why is abnormal kidney function in younger ages an important topic for life underwriters?
Declining kidney function is something that is commonly associated with older ages, however, as life insurance underwriters we sometimes see test results in either the blood profile or urinalysis that reflect unusual kidney function in otherwise young and healthy people. What could explain this?
While chronic kidney disease is certainly seen more often in elder ages, the term ‘chronic kidney disease,’ as our Renal Disorders course teaches, is really an umbrella term used to characterize several different kidney impairments - some of which may present earlier on in life.
As an underwriter who once grappled with these unusual tests (and still does, from time to time), I thought it would be beneficial to put together a little cheat guide to explain some of the more common wonky kidney function tests (KFT) results that we come across. Before we get started, let’s recap on exactly which tests we see on the insurance labs.
(1) Serum Creatinine
First off, the term “serum” refers to the blood – not to be confused with urine creatinine, which is a test that is administered to measure how diluted a urine sample is. Serum, or blood creatinine is a waste molecule that is generated by muscle metabolism, secreted into the blood stream and eventually cleared by the kidneys. When we see elevated amount of serum creatinine on a lab result, we may infer that the kidneys are not clearing this molecule as fast as they should; in other words, they may be impaired. Low values of serum creatinine are generally not a concern.
Why would Serum Creatinine be elevated in a young, healthy individual?
While elevated serum creatinine should always warrant concern when dealing with an individual over the age 50, there could be many benign reasons to explain this result in a younger client including:
- Recent physical exercise
- History of high blood pressure (if so, check to see if they are on a diuretic -Hydrochlorothiazide is a popular one- these medications can dehydrate a person and lead to an elevated blood creatinine result
If you’re worried about hypertensive kidney damage, take a quick peek at their urinalysis. Kidney disease that is brought on by uncontrolled blood pressure will usually be accompanied by elevated urine albumin, and possibly protein.
(2) Blood Urea Nitrogen
Also known as BUN (not the ‘bun’) is a test to measure the amount of urea in the bloodstream. Urea is another waste molecule that is cleared by the kidneys, as with creatinine; however, urea is produced in the liver. We worry about rising values of BUN for the same reasons as we do blood creatinine – that the kidneys may be impaired, as they are not clearing these waste molecules as fast as they should.
Why would Blood Urea Nitrogen be elevated in a young, healthy individual?
I believe we tend to see a fair amount of borderline-elevated BUN values on insurance labs; that is, not significantly elevated but perhaps just a bit above the normal limit. The truth is, this test is susceptible to a fair amount of ‘noise’ through a person’s diet. If it is truly a kidney impairment that you are dealing with, then the serum creatinine test should be elevated alongside it. If that is normal though, and the BUN is not through the roof, it’s usually safe to chalk this up to benign causes.PRO TIP: Watch out for low Blood Urea Nitrogen values!
Unlike serum creatinine, where low values are usually glossed over, low values of the BUN can sometimes indicate a liver impairment. You should cross-check a person’s liver function test (which you can learn more about it here), but if these are normal then this is usually OK.
(3) Urine Protein
Proteins are fairly large molecules in the bloodstream, and it is not common to see high concentrations of these in a urine sample. The reason for this is that the filter units for the kidneys (the nephrons) are possessed of membranes that aren’t exactly permeable to proteins. So, when we see proteins in the urine, we can assume that it is due to either a) damaged membranes or b) contamination. Here, contamination refers to the presence of proteins in the urine sample from a source downstream of the kidneys.
Why would Urine Protein be elevated in a young, healthy individual?
It could be a sign of underlying, perhaps undiagnosed kidney disease or just simple contamination. The best way to verify either way is to request a microalbumin screen (discussed next). Protein in the urine in the absence of elevated albumin is often just contamination, either by infection or an outside source. If there is elevated urine albumin alongside of this though, there may be a concern for glomerular disease (another topic covered in our renal diseases course).
The term ‘microalbumin’ refers to the test administered on the urinalysis to measure the quantities of albumin in the urine. Albumin is also present in the blood, but there is another test to measure that which is not covered in this blog. Albumin is a specific kind of protein, and like other proteins it is usually filtered out from the nephrons in the kidney.
Why would Microalbumin be elevated in a young, healthy individual?
The number one cause of elevated urine albumin in such cases is actually orthostatic – a phenomenon in which long periods of standing can lead to a natural elevation of albumin in the urine. This is benign, and of little concern. Still, we need to properly evaluate for other insidious causes. Is the urine protein elevated as well? If so, this could point to an insidious illness, such as glomerulonephritis. If the person’s blood pressure is remarkably elevated as well, this could be cause for concern. In essence, you will want to pay attention to the range of KFT’s available in order to assess the importance of an elevation.
Thanks for tuning in. Make sure to subscribe to receive the next one in your inbox! In the meantime, if you are looking for more information on kidney function and disease, be sure to check out our course on renal disorders.