DEAR DR. GOTT: I am a white male with a question about my creatinine history. In 2009 it was 1.09; in 2010 1.11; in 2011 1.15; and this year I’m 1.19. For the first three years of my testing, the reference range was between 0.67 and 1.54 but for some unexplained reason, the upper limit range was reduced to 1.18. Why?
DEAR READER: Reference ranges, otherwise known as “normal range” values are used by health care professionals to assist doctors and laboratory technicians in interpreting test results from blood, urine, cerebral spinal fluid and/or feces. Simply stated, the range calculated is determined through collecting data from countless numbers of tests, with 95% of the population falling within the “normal” range, and the remaining five percent falling out of that range and being considered “abnormal”. Ranges are relatively consistent nationwide; however, can vary slightly depending on which facility performs the test.
As researchers investigate specific diseases and disorders, they may determine those numbers originally thought to be alright in the past simply aren’t satisfactory any longer. So, they adjust them. That’s what research is all about. The more we know about a specific disorder, the better we are at helping you stay healthy, even if that means modifying those ranges. Let me give you an example. Not too many years ago, a normal systolic blood pressure reading (the first number) was 100 plus your age. That’s all well and good if you are or were 27. However, if you were 82, that means your systolic was 182 and definitely higher than it should have been. Clearly, with research, a modification was in order. That’s why your hospital or outside lab adjusted the figures.
One set of values we often hear of involves cholesterol. Optimal levels for total cholesterol are less than 200. Anything between 200 and 239 is considered borderline; greater amounts are considered excessively high. Now let’s enter a cardiac condition into the equation. A cardiologist may want that level somewhere around 145 which will require religious dietary restrictions, over-the-counter remedies, prescription drugs, statins, or a combination thereof.
The most common measurements reported are stated in deciliters (dL) and Internal Units (IU). Blood testing is generally from the vein, since the standard method of obtaining a sample is through venipuncture.
You mention having a creatinine done for four years in a row but didn’t explain why. This test is one of several components in a complete metabolic profile and could have been done as part of an annual examination or you could have an issue with your kidneys. Abnormalities might occur because of hypertension, diabetes, hypercholesterolemia, a kidney stone or kidney disease. If you do have a kidney disorder, your physician might be paying close attention to your creatinine. Or, perhaps your physician placed you on an angiotensin-converting enzyme inhibitor (otherwise known as an ACE inhibitor), you have been given a drug for chemotherapy, or you may be on a heavy-duty antibiotic, all of which could result in abnormal readings. Dietary intake, recent meat consumption, high impact sports, muscle mass, and amputation can also alter levels.
Readers who would like related information can order my Health Report(s) “Understanding Cholesterol” and “Kidney Disorders” by sending a self-addressed, stamped number 10 envelope and $2 US or money order for each report to my attention at PO Box 433, Lakeville, CT 06039. Be sure to mention the title(s) when writing or print out an order form from my website www.AskDrGottMD.com.
