Clinical analysis: how to read the results
The performance of clinical analyses provides important information about our health or disease, which helps the physician to make a diagnosis and, if necessary, to choose the best treatment option.
They are also fundamental for prognosis, monitoring, follow-up and prevention.
There are a series of reference values that help us to get an idea of the results of the analyses. However, many factors can interfere with the interpretation of the final values, so only the physician is qualified to draw conclusions.
Some examples that are considered in the final interpretation of results include:
- Medical condition
- Medical and family history
- Smoking habits
- Profile of a “normal” person
The analyses can be further divided into six main groups:
- Urine analysis
- Stool analysis
Most frequent clinical analyses
The CBC assesses all cellular components present in the blood. In other words:
Red blood cells
Measures the number of red blood cells, the blood cells that carry hemoglobin, a protein that transports oxygen. When this number is too low, we can suffer from anemia, which causes fatigue and weakness.
If the values are too high, the blood can become excessively thick, which can cause certain symptoms, such as headaches, dizziness, or even increase cardiovascular risk.
4.2 to 5.9 x 1012 cells/L (generally varies between women and men)
A protein that gives blood its red color and is located inside erythrocytes. It is responsible for oxygen transport. It is used, for example, to assess the presence of anemia.
Reference values for women: 12 to 16 g/dL
Reference values for men: 15 to 17 g/dL
Leukocytes (white blood cells)
The body’s defense cells. They are responsible for fighting infections and are part of the immune system. There are five main types:
- Neutrophils (nullify bacteria and fungi);
- Lymphocytes (participate in the defense against viral infections, detect and destroy certain cancer cells, and produce antibodies) ;
- Monocytes (ingest dead cells and defend the body against infectious organisms);
- Eosinophils (kill parasites, destroy cancer cells, and are involved in allergic reactions);
- Basophils (also involved in allergic reactions).
Reference values: 3.9 to 10.7 cells/L
Platelets are cell-like particles, smaller than red or white blood cells. They are involved in the coagulation process, fighting hemorrhage.
When the amount is too low, the risk of hematoma and abnormal bleeding is higher. If it is too high (thrombocytopenia), the blood can clot, which is also a risk factor for vascular complications, and a transient ischemic attack can occur (thrombocytosis).
Reference values: 150 to 350 x 109 cells/L
The main biochemical tests are as follows:
An increase in the concentration of uric acid in the blood is called hyperuricemia. It can be caused, for example, by metabolic or kidney diseases, excessive consumption of proteins or alcohol. In cases of gout or kidney stones.
Reference values: 2.5 to 8 mg/dL
It is a protein produced by the liver and also the most abundant in the blood. Its deficiency may indicate an inadequate diet, or the presence of liver disease.
Reference values: 3.5 to 5.5 g/dL
This “famous” molecule called cholesterol can be good (HDL) or bad (LDL). In the analyses, the total cholesterol is also evaluated. Excessive LDL values are a risk factor for cardiovascular problems.
Cholesterol is a steroid molecule found in all cells of the body and is essential for the formation of cell membranes, the synthesis of hormones, the digestion of fats, the production of bile, the metabolism of vitamins A, D, E and K, among other functions.
The most frequently measured cholesterol in clinical analyses is LDL (Low Density Lipoprotein), HDL (High Density Lipoprotein) and total cholesterol. HDL is thought to have a protective role – it is commonly referred to as the “good” cholesterol.
On the other hand, high levels of LDL (bad) cholesterol can contribute to the formation and development of atherosclerotic plaques on the walls of the arteries – atherosclerosis – which can lead to total blockage and consequent ischemia of the affected organs.
Total cholesterol – 150 to 199 mg/dL
HDL for men – over 35 mg/dL
HDL for women – over 45 mg/dL
LDL – less than 130 mg/dL
It is continuously produced by the muscles and eliminated by the kidneys. Its assessment therefore provides important information about renal function.
Reference values: 0.7 to 1.3 md/dL
These are minerals that circulate in the body. For example, salt (sodium), potassium, calcium and magnesium are electrolytes.
They help with many functions in the body, including controlling nerve and muscle function, balancing the amount of water in the body and balancing acid levels.
The kidneys are responsible for maintaining the proper balance of electrolytes in the blood.
Electrolyte assessment is very important for monitoring diseases such as hypertension, heart failure, and liver or kidney disease.
Magnesium – 1.1 to 2 mEq/L
Sodium – 135 to 145 mmol/L
Potassium – 3.6 to 5.1 mmol/L
Chloride – 99 to 109 mmol/L
Glucose is a carbohydrate that is fundamental for energy production. However, when it is present in excess in our body, it can be suggestive of a diagnosis of diabetes.
Reference values: 70 to 105 mg/dL
Urinalysis can be performed to detect or measure several substances present, namely protein, glucose (sugar), ketones (chemicals produced by the body due to a lack of insulin), bilirubin, urobilinogen (may be associated with certain anemias, liver disease, or in cases of fever and dehydration), leukocytes (may indicate infection or inflammation in the urinary tract), and blood.
This study can detect problems such as proteinuria (abnormal amount of protein), diabetes mellitus, liver problems, and urinary tract infection or inflammation. Urine density reflects the ability of the kidney to concentrate or dilute and the level of hydration.
Reference values: pH between 5 and 9
Stool analysis can detect the presence of parasites or blood, which helps detect, for example, digestive disorders and cancer.
0 to 10 (negative)
10 to 19 (weak positive)
20 to 100 (positive)
100 and more (strongly positive)
It consists of a few tests that assess the presence of all factors involved in blood clotting.
The main tests are as follows:
- Bleeding time (BT);
- Prothrombin time (PT);
- Activated partial thromboplastin time (APT);
- Thrombin time (TT);
- Platelet count.