When conducting any diagnostic measures, the research results are considered comprehensively. In this case, all indicators are taken into account: the general condition of the patient, the nature of the pathology, symptoms.
Quantitative and qualitative research
The results of a number of laboratory tests are given to patients in the form of "positive" or "negative". This form is considered a quality characteristic. An example is an analysis of antibodies to a particular infection. A positive result indicates the presence of these antibodies in the material.
What does "reference value" mean?
With a quantitative type of study, the results are presented in the form of numbers. In this case, there is a range of norms, as well as average indicators. Reference value in analyzes is a medical term used to evaluate results in laboratory studies. It is defined as the average value of a certain indicator. These data were obtained by examining a healthy part of the population. For starters, you can consider some reference values of thyroid hormones. For example, for free T3, 1.2-2.8 mMe / L will be normal, and for thyroxine (total), 60.0-160.0 nmol / L. This is what the index of TSH analysis might look like : reference values are 0.5-5.0 μMU / ml, and the result itself is 2.0. As can be seen from the last example, the figure obtained in the study is in the normal range.
How are normal boundaries determined?
The only way, as mentioned above, is the examination of healthy people. The first step is to sample the population. For example, healthy women are invited whose age is from twenty to thirty years. Most of them are assigned clinical studies. The results are reduced to average figures, calculating the range in which the reference values are. Deviation from normal values (one way or another) by two standard units is allowed.
Why do different laboratories produce different results?
Depending on the applied research method and measuring instruments, one or another reference value is given. Different laboratories may use different equipment, apply one or another unit of calculation. In accordance with this, ranges of indicators are also established.
Upon receipt of the result, the form should contain the numbers and units of measurement used in a particular laboratory. Thus, in medicine, for example, there are no uniform reference values for a blood test. When viewing the results, a specialist should refer to the figures used by the institution in which the patient was examined. The difference can be seen by considering, for example, some reference values of a biochemical blood test. Thus, the range of indicators for ethylidene in the study of the G7PNP method is 28-100 U / L, and the CNPG3 method is 22-80 U / L.
Why can indicators go beyond the norm?
The reference value in the analyzes is statistical data, but not a biological law. In some cases, deviations from the limits of the established ranges can be observed even in healthy people. What could be causing this? Among the many causes of deviations, physiological characteristics of the body are of particular importance. If a specialist recommends passing one laboratory test several times, then there is a certain probability that a deviation from normal limits will appear in the results. According to biological reasons, indicators can change daily. To compare the results, the doctor prescribes the tests again. As a rule, diagnostic conclusions are made not in accordance with single indicators, but in assessing the dynamics of changes. In healthy people, data may not fall into generally accepted ranges.
Moreover, for the people themselves, the results will be considered the norm. Such cases usually involve slight deviations. Nevertheless, indicators that do not fall into reference values may indicate disorders in the body that require further diagnostic measures. The specialist, evaluating the results of studies, takes into account the general condition of the patient, the clinical picture, studies the medical history and other factors. As a result, the doctor determines what the deviation from normal numbers indicates.
What factors can influence research results?
The laboratory can give the patient results according to his gender and age. For example, the reference values of creatinine (in the study of serum) in men up to 50 years old are 74-110 μmol / l, after 50 years - 70-127 μmol / l. In women, indicators are established regardless of age and are 60-100 μmol / L. The hCG reference values for the fair sex depend on whether the patient is pregnant or not. The results of the studies may be affected by the treatment received, the features of the daily regimen and nutrition. An important factor is bad habits: smoking, alcohol or coffee abuse. Even the patient's posture during the delivery of the material can affect performance. For example, the content of calcium and albumin can increase when the patient's position changes from horizontal to vertical. To obtain a more accurate result, before the study, a specialist can recommend excluding physical activity, stressful situations, stop smoking and drinking alcohol, taking medications and vitamins.
The effect of physical activity on the results
A visit on the eve of a gym study is not recommended. Physical activity affects the enzymatic activity of creatine phosphogenase, lactate dehydrogenase, aspartate aminotransferase. Athletes who have been involved in weightlifting or athletics for many years may experience elevated levels of luteinizing hormone, platelet count, and testosterone. Given all these factors, certain rules should be followed before passing tests. In preparation for certain studies, the doctor, as a rule, gives special recommendations. If the patient follows the instructions of a specialist, then he is much more likely to get accurate and correct results.
Common misconceptions
There are several erroneous opinions about reference values and, in fact, research results. Many people believe that deviations from the norm certainly indicate violations in the body. However, this is not always the case. Results that go beyond generally accepted ranges indicate the need for further examinations or for reanalysis. It is likely that the result does not indicate violations, but falls in 5% of cases in which deviations are observed in healthy people. In any case, the doctor will take the necessary measures to accurately assess the situation. As mentioned above, there are many factors that can affect the result. For example, high blood sugar may not indicate diabetes, but nutritional errors. Lipid levels increase if the test is not done on an empty stomach. The increase in the content of liver enzymes may be associated with the use of alcohol on the eve of the study, and not with cirrhosis. Among other things, the results are also affected by the medications taken. Today, pharmacological enterprises produce a huge amount of drugs. Laboratories sometimes simply do not have time to evaluate their effect on blood counts or other test material. In a number of cases, the values may return to normal on their own if they were at the boundary of the reference values.
Should I worry if the results of research are within the normal range?
In general, such indicators are undoubtedly a good sign and indicate the absence of any disturbances in the body. However, according to many experts, a certain set of studies does not guarantee the complete absence of health problems. In the statistical processing of reference ranges, there is always a partial coincidence of the results of people with pathologies and healthy ones. In other words, in the latter, in the absence of disturbances in the body's activity, indicators may deviate from the norm. Similarly, in people with pathologies, test results may be within normal limits. To clarify the indicators, as a rule, repeated studies are appointed after a certain period. When assessing the dynamics of changes, the specialist either notes the absence of violations or suspects any pathology. In the second case, additional examinations are prescribed to clarify the diagnosis.