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Kidney Diseases

Dilute Urine

08/20/2008

Question:

I have had 3 urinalysis`, a random specimen upon initial visit, specific gravity, and an 24 hour osmolality. All 3 have indicated dilute urine. I have never consumed the recommended amount of water.

Prior to the last two tests, the specific gravity test and the 24 osmolality, I knew I`d be having blood drawn for other testing; therefore, I drank about 2 liters of water. (I know that it is easier to have blood drawn when you are properly hydrated.)

My question is this: Since I have probably been chronically dehydrated, due to the lack of a normal consumption of fluid, is it possible that by consuming a normal intake of 2 liters of water, over the course of the day prior to these tests and given the fact that my body is just not used to a normal intake,cause the urine test to indicate dilute urine due to my body reacting as though it was over-hydrated? Is that plausible?

My physician is sending me to an endocrinologist. I assume she will want a urinalysis test (specific gravity and/or osmolality) in the absence of consuming any liquids to see if this brings the concentration level up.

Thank you.

Answer:

Most people probably consume at least 3 or 4 8-ounce glasses of fluid daily, as water, coffee, juice, pop, etc.  This is plenty, because food also contains a lot of water (for instance, many fruits and vegetables are 90+% water, and meats are about 50-60% water).  Regardless of how much water you are used to consuming, if you drink a large amount (like 2 liters) before having the urine tests, it would not be at all surprising that your urine would be dilute.  In other words, a normal kidney, when given a lot of water, puts out a lot of water (i.e., a dilute urine): that's its job.

A person who is unable to produce a concentrated urine has to urinate a lot, day and night, and is always thirsty.  This does not sound like you.  You might explain to your doctor that you deliberately drank a lot of water before being tested; because a repeat urine test done first thing in the morning (before you drink anything) could save you a trip to the endocrinologist.   

 

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University