Cómo interpretar un análisis clínico: claves sobre valores y riesgos

Production: Popular Science China

Author: Huang Xiangning, Xinhai Hospital of Guangzhou.

Producer: Guangdong Provincial Association for Science and Technology.

What do the red and green arrows on the test report mean? This is because the test results exceed the biological reference range (also commonly referred to as 'reference range').

After reviewing the test results, the doctor may sometimes conclude that there is no issue and only periodic monitoring is required. At other times, treatment may be necessary, or emergency intervention may be organized. This is because, in medical diagnosis, determining the treatment plan or other physiological assessments requires consideration of related concepts such as biological reference range, medical decision level, and critical values.

The biological reference range refers to the normal range obtained when measuring biomarkers (such as biochemical components, hormones, etc.) in a specific population. These reference ranges are usually based on laboratory data from healthy individuals, helping doctors determine whether an individual's physiological state is normal. Reference ranges can be influenced by various factors including age, sex, ethnicity, and health status. Therefore, when interpreting test results, these factors must be considered.

The biological reference interval is a statistical concept generally derived from measurement data of a large number of healthy individuals, grouped and statistically analyzed according to factors such as age, sex, and region. Typically, a reference interval is determined that encompasses between 2.5% and 97.5%, thus establishing the reference range. Therefore, outside the biological reference range, there will also be a percentage (5%) of healthy individuals.

The reference range in the laboratory report is established based on biological reference intervals. It usually comes from industry health standards, manufacturer reagent instructions, or specialized literature.

For the same project, reference ranges from different detection systems used by various laboratories may differ.

The medical decision level refers to the standards and criteria that physicians rely on when making clinical decisions in medical practice. These standards and criteria may include scientific evidence, the specific conditions of the patient, medical guidelines, and the physician's professional experience. The level of medical decision-making directly affects the quality of healthcare and the treatment outcomes for patients, making it significant in the medical field.

The medical decision level refers to the concentration of a measured component that plays a key role in the diagnosis or treatment of diseases. It is generally based on extensive medical practice.

Quantitative test results in medicine are generally expressed in terms of concentration, while qualitative test results are based on a critical value (cut-off value), i.e., the threshold for determining a positive result.

| Item | Biological Reference Range | Medical Decision Level | |---------------------|----------------------------------------|-------------------------------------------| | Definition | Normal range of a biomarker in a specific population | Specific values or ranges to guide clinical decisions | | Purpose | Provide a reference for normal and abnormal states | Assist doctors in diagnosis and treatment decisions | | Data Source | Obtained through statistical analysis of healthy populations | Derived from clinical studies, expert consensus, etc. | | Application Field | Laboratory result interpretation, health assessment | Diagnosis, treatment, prognostic evaluation | | Variation Impact | May be affected by population characteristics (age, sex, etc.) | May be adjusted due to disease characteristics, treatment plans | | Update Frequency | Continuously updated with new research findings | Updated regularly when assessing clinical practices and guidelines |

Critical values refer to test results whose values exceed normal ranges and may pose an immediate threat to patient health. These values typically prompt physicians to take immediate action to prevent potential serious consequences. For instance, some laboratory tests such as blood glucose, potassium, or sodium levels can pose a life-threatening situation if results are abnormal. Therefore, medical personnel must respond promptly to these critical values.

Critical values refer to test results that are extremely abnormal and, if not addressed in time, can jeopardize the patient's life. Not all laboratory parameters require the definition of a critical value; hospitals of different specialties must select appropriate critical values based on their work characteristics.

There are also significant infectious diseases under government monitoring, which were designated as critical values during the pandemic.

Summary of Demonstration.

Finally, we will take the blood glucose level as an example to demonstrate (see the glucose level chart).

The range that includes both normal upper and lower limits, also known as the biological reference interval, is the reference range that commonly appears in test reports. If the fasting blood glucose level is between 3.9 millimoles per liter and 6.1 millimoles per liter, the test result can be determined as normal.

When fasting blood glucose levels fall below or exceed the reference range, this may indicate potential health issues, and consulting a physician for a more detailed diagnosis and treatment is necessary. According to the diabetes diagnostic standards mentioned, the condition is met when at least one of the following criteria is present: fasting plasma glucose (FPG) is equal to or greater than 7.0 millimoles per liter; blood glucose level two hours after an oral glucose load (2h-PG) is equal to or greater than 11.1 millimoles per liter; or typical diabetes symptoms (increased thirst, increased appetite, increased urination, and unexplained weight loss) occur alongside a random blood glucose level equal to or greater than 11.1 millimoles per liter.

Glucose, as an important source of energy and structural material in the body, is maintained in a stable state under the regulation of various internal factors. The blood glucose level is a key indicator of sugar content in the body. A fasting glucose level below 2.8 millimoles per liter can lead to hypoglycemic coma; while a level above 25.0 millimoles per liter can cause hyperglycemic coma, osmotic polyuria accompanied by severe dehydration, and ketoacidosis. Thus, establishing critical values can alert patients that they are in a life-threatening risk state, and providing timely and effective treatment in such cases can save the patient's life, otherwise serious consequences may occur.

In summary, the reference range in the analysis report (biological reference interval) can be used to determine whether the results are within the normal range. If they are outside this range, there is no cause for alarm; technical issues should be addressed by professionals, as a small portion of the normal population may be outside the reference range. The diagnosis and treatment of diseases still require physicians to rely on medical decision levels and critical values for a more accurate judgment.

Content provided by: Guangdong Provincial Association for Science and Technology.

Content resources are provided by the project unit.