Table of Contents
A study done in rats showed that higher total and free testosterone blood levels produced by testosterone treatment were associated with higher creatinine and lower creatinine clearance (Effects of Testosterone Replacement on Renal Function and Apoptosison Mesangial and Renal Tubule Cells in Rats)
Creatinine is a chemical waste product that's produced by your muscle metabolism and to a smaller extent by eating meat. Healthy kidneys filter creatinine and other waste products from your blood. The filtered waste products leave your body in your urine.
If your kidneys aren't functioning properly, an increased level of creatinine may accumulate in your blood. A serum creatinine test measures the level of creatinine in your blood and gives you an estimate of how well your kidneys filter (glomerular filtration rate). A creatinine urine test can measure creatinine in your urine.
The creatinine level also varies according to a person's size and muscle mass. It can also increase with the use of high protein diets, excessive exercise, supplements containing creatine, dehydration, and medications that affect kidney function (tenofovir, etc), long term high blood pressure, etc.
Normal Results
A normal result is 0.7 to 1.3 mg/dL for men and 0.6 to 1.1 mg/dL for women.
Women usually have a lower creatinine level than men. This is because women usually have less muscle mass than men.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
Glomerular Filtration Rate
Also called: GFR
Kidney function is measured by how well the kidneys clean the blood. The glomerular filtration rate (GFR) is a good way to find out the patient's stage of kidney disease. The main factor in estimating the GFR is finding out the level of creatinine in the blood. Your doctor will order blood tests that will list your serum creatinine. When kidneys are functioning, they remove creatinine from the blood. As kidney function slows, blood levels of creatinine rise.
A mathematical equation is used to estimate the GFR. In addition to serum creatinine, other factors in the equation include age, race and gender. Sometimes, optional factors such as weight, blood urea nitrogen (BUN) and serum albumin are used to get the patient's GFR level. Once the GFR level is known the stage can be determined.
Normal eGFR are those above 60 ml/min. If your GFR is under 60 ml/min, please consult your doctor.
You can measure your creatinine clearance (GFR) here if not provided by your lab company: http://www.pharmacologyweekly.com/app/medical-calculators/creatinine-clearance-crcl-calculator
Note: Creatinine clearance reductions of under 60 ml/min are rare in men using testosterone replacement therapy, but always keep an eye on this important parameter!
