Laboratory test results reported as numbers are not meaningful by themselves. Though the term "reference interval" is usually the term preferred by laboratory and other health professionals, the more commonly-known term is "reference range," so that is the term used throughout this article. 8605 SW Creekside Place, Beaverton, OR 97008, How Reference Ranges Determine a "Normal" Lab Test Result, ZRT Test Specifications (validation data), Heavy Metals & Essential Elements Reference Ranges, Dried Urine Reference Ranges - Hormone Metabolites, Dried Urine Reference Ranges - Neurotransmitters, [1] Garber JR, et al; American Association of Clinical Endocrinologists and American Thyroid Association Taskforce on Hypothyroidism in Adults. Couple this with differences in lifestyles, physiology, dietary habits, and genetic heredity, and it’s even more difficult to define, let alone find, a normal population. The finding of tissue transglutaminase (tTG)-IgA antibodies is specific for celiac disease and possibly for dermatitis herpetiformis. For example, if the data set consisted of 120 specimens, the 2.5 and 97.5 percentile ranks would be calculated by multiplying; 120 x 0.025 = 3. 2008;29 (Suppl i):S93-S97. A blood sample is taken from a vein in the arm and sent off to the laboratory for analysis. Your report may look something like this, indicating that this test result falls within the established normal reference range: (To see an example of what a full report with several test results looks like, see this sample cumulative report.). Confirmed results from reference data sets received as of October 30, 2020, are shown in Table 2. 2007;28:115-121. For some tests, there is no single reference range that applies to everyone. In most European countries as well as Canada, the cholesterol levels are measured in millimoles (mmol) of cholesterol per liter (L) of blood. Every laboratory identifies certain key tests that have been associated with these life-threatening events whereby critical values are required to be immediately reported to the health practitioner. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’ If, for instance, we take the upper and lower reference limits for sodium as 135 and 145 mmol/L, respectively, the range is 10 mmol/L while the interval is 135–145 mmol/L. gtt test result interpretation. 50% - 65% of men with psa scores over 10 ng/ml develop prostate cancer. Davis Company; 2000:10-17. 15% of men with a PSA level less than 4 ng/ml go on to develop prostate cancer. Having a higher-than-normal blood calcium level is called hypercalcemia.. … Roberta Reed, PhD, Mary Imogene Bassett Hosp., Cooperstown, NY, (by Eric Seaborg), 6/7/01. To eliminate abnormal results at either end of the range spectrum, the values between the 5. percentiles of the range usually comprise the reference range. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556592/. Important Greyhound blood test value differences from other dogs. You may notice that the few, select reference ranges listed on this site apply only to adults, and there are, We want you to be informed, but we don't pretend to take the place of communication between you and your healthcare provider. But if you're engaging in high-risk behavior, such as drug and alcohol abuse or a poor diet, it only means "so far so good," and the potential consequences haven't caught up with you yet. However, the true meaning of a test result—whether it indicates that you are sick or well or at risk for a health condition—can only be known when all the other information your provider has gathered about your health, including the results of a physical exam, your health and family history, recent changes in your health, any medications you are taking, and other non-laboratory testing. Accessed August 2015. The Science of Laboratory Diagnosis. The type of sample used (for example, whole blood, plasma, serum, urine, saliva, or other body fluid), The time of day when a sample is collected, Whether the test is performed on a patient who has been fasting, The phase of a female patient's menstrual cycle at the time of testing or whether she is in perimenopause or menopause. A simple implementation is as Co-testing with an HPV test and Pap test, as recommended by current guidelines, can determine whether cervical cells are infected with a high-risk type of HPV and identify abnormal changes in … The term "reference range" is preferred over "normal range" because the reference population can be clearly defined. Critical results may also be referred to as “panic” values. For the most part, the laboratory values obtained in elderly persons seem to fall into our traditional or so-called normal ranges, and little evidence supports the need for separate sets of reference ranges for the elderly. Clin Biochem Rev. (July 2012) Al-Borai A. Frequently-Asked-Questions on Reference Intervals and Biological Variation. For example, pregnancy changes many aspects of a woman's body chemistry, so what is typical for pregnant women is not typical for those who are not pregnant. Most laboratories establish their reference ranges from a large population of people where detailed information on health status, stage of life (premenopausal vs. postmenopausal), and medications and hormones used is unknown, and therefore not taken into account. How do the results fit with the rest of your clinical picture? Problem is caused by inherent factors of age, sex, body build, occupation, genetic background, diet, altitude of residence etc., which affect test values. Are my laboratory results normal? We want you to understand what each test on this site is for, but because we can't be aware of all the factors that could affect your test results, we can’t interpret the results without more information. The short answer to this question is by testing a large number of people who have key similarities and observing what appears to be "typical" for them.