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Kidney Function

See also the information on liver function.

What Does the Kidney Do?

Along with the liver, the kidneys are another part of the waste processing system of the body -- thus urine goes from the kidneys into the bladder.  The liver filters metabolic waste products, excess sodium and water from the blood, thereby helping to eliminate them from the body.  The kidneys also help regulate blood pressure and the production of red blood cells.

Medscape (you may need to register to access this article), has a paper on Chronic Kidney Disease: Chronic Kidney Disease: It's Time to Recognize Its Presence in Our Patients With Hypertension. Posted 10/22/2004, by Jan Basile, MD.  This is an informative article about kidney function.


Renal - pertaining to the kidneys.


As an example of drug-induced kidney problems consider Zometa. The prescribing directions require measuring the creatinine level prior to administering Zometa. Clinical trial data showed increased renal(kidney) function deterioration when Zometa was given times shorter than 15 minutes and at higher than 4 mg doses (e.g., 8mg/5 minutes). Thus the criteria for dosing at 4mg/>15 minutes.

There are other drugs that can impact the kidney  as well.

What tests are run to assess kidney function?2

You cannot live without adequately functioning kidneys and liver.  Therefore, it may be necessary with certain drugs to run some of the following tests periodically to determine whether those drugs are harming these vital organs.  Liver and kidney insufficiency are also dangerous associated diseases that can aggravate the problem of cancer. The following tests are often given monthly as part of the complete metabolic panel with blood drawn before chemotherapy or during regular monitoring of your disease.

Please refer to the references for a more complete description of the various tests listed below.

BUN (Blood Urea Nitrogen or Urea Nitrogen).   This is the concentration of nitrogen(within urea) in the serum(but not in red blood cells).  A waste product, derived from protein breakdown, produced in the liver and excreted by way of the kidneys. High values may mean that the kidneys are not working as well as they should. BUN is also elevated by blood loss, dehydration, high protein diets and/or strenuous exercise which may temporarily and artificially raise levels. A low BUN level may be the result of liver disease, a low protein diet, pregnancy, or drinking an extreme amount of water.

Creatinine.  A waste product largely from muscle metabolism (breakdown). Concentration of creatinine in the blood depends upon the amount of muscle that you have and the ability of your kidneys to excrete creatinine. High values, especially with high BUN levels, may indicate problems with the kidneys. Low values are generally not considered significant.

Calcium.  Calcium is one of the most important elements in the boby. The parathyroid glands and the kidneys control the amount of calcium in the blood. The parathyroid gland is the main regulator of calcium in the body.  Nearly all of the calcium in the body is found in bone (99%). The remaining 1% is very important for proper clotting, nerve, and cell and enzyme activity. An elevated calcium level can be due to medication (such as too much calcitriol-synthetic vitamin D), inherited disorders of calcium handling in the kidneys, bone disease, or excess parathyroid gland activity or vitamin D. Low calcium can be due to malnutrition, drugs and certain metabolic disorders.

Sodium.  An electrolyte regulated by the kidneys and adrenal glands. This element plays an important role in the water/salt balance in your body.

Potassium.  Potassium is an electrolyte found  primarily inside cells and must be controlled very carefully by the kidneys.  Its role is to maintain water balance inside the cells and to help in the transmission of nerve impulses. A low potassium level can cause muscle weakness and heart problems. A high potassium level can be found in kidney disease or in over ingestion of potassium supplements.

Chloride.   Chloride is an electrolyte regulated by the kidneys and adrenal glands.  Chloride is important to the function of nerves, muscles, and cells.  It is usually associated with a high or low level of sodium or potassium.

Some drugs taken by prostate cancer patients such as estrogens and corticosteriods can cause increased chloride(there are a number of other durgs also that can do this). See (2). Both drugs and other causes can lead to a decrease in serum chloride.

CO2.  Co2 levels reflects the acid status of your blood. See the references listed under (2) for details on the cause of high or low levels.   Corticosteriods as well as kidney disease can be involved.

BUN/Creatinine Ratio - This ratio is sometimes used or diagnostic purposes.

Example Complete Metabolic Panel

Note: the yellow area highlights kidney function tests. Reference ranges may vary from laboratory to laboratory. HI and LO are relative to the Reference Range.

Typical Complete Metabolic Panel - Blood Tests

Test Flag, LO=Low, HI= High Result Units Reference Range4
Sodium LO 136. mmol/L 137 - 145
Potassium   4.0 mmol/L 3.6 - 5.0
Chloride   103. mmol/L 98. - 107.
CO2   30. mmol/L 22. - 31.
Alkaline Phosphatase   39. U/L 38. - 126.
Total Bilirubin   0.3 mg/dL .2 - 1.3
AST HI 67. U/L 8. - 50.
ALT HI 104. U/L 9. - 72.
Albumin LO 3.4 g/dL 3.9 - 5.0
Total Protein   6.8 g/dL 6.3 - 8.2
Creatinine (*)   1.0 mg/dL 0.7 - 1.5

Urea Nitrogen


  18. mg/dL 7.0 - 20.
Calcium   9.1 mg/dL 8.4 - 10.2
Glucose   92. mg/dL 65. - 110.
LDH   516 U/L 313 - 618

(*) Units of μmol/L result in a reference range, for example,  of 70-120 μmol/L.


1. D. Nicoli et al, Pocket Guide to Diagnostic Tests, 3rd edition, McGraw-Hill 2001.

2. There are a number of websites that provide information on diagnostic tests, here are a few:

The Blood Book - all about blood tests: http://www.bloodbook.com/test-result.html

Lab Tests Online:



For Specific Information on ALP (Alkaline Phosphatase) visit



National library of medicine/National Insitutes of Health Medical Encyclopedia:



The Surgery Encyclopedia has a page devoted to kidney function tests.


3. The Life Extension Foundation, www.lef.org, has a discussion of liver degenerative disease at



4. Reference Ranges and What they Mean. See  www.labtestsonline.org/understanding/features/ref_ranges.html


Author: Howard Hansen.  Last Update 3/16/07




The information on this website was written between 2001 and 2010 by and for men with HRPCa (now called CRPC or mCRPC). The website content was developed for educational purposes only and does not replace or amend professional medical advice. Although proven and potential treatments have substantially changed since 2010, much of the website content is still relevant and helpful. See About Us for our policies and contact information. We are a 501(c)(3) not-for-profit public charity. 2001-2015 HRPCa Association, Inc.