Biochemical tests, often called blood chemistry tests, measure specific substances—such as metabolites, enzymes, and electrolytes—in blood or urine. The results provide a functional snapshot of the body’s internal processes, indicating how well organs are operating and whether metabolic systems are balanced. Analyzing these components helps healthcare providers gain insight into a person’s overall health and detect potential imbalances.
Markers of Energy and Cardiovascular Health
One of the most frequently ordered biochemical tests focuses on glucose, which is the body’s main source of energy derived from food. Measuring blood sugar levels helps determine the body’s ability to regulate this fuel source, which is directly related to the risk of developing diabetes or pre-diabetes. For a longer-term view, the Hemoglobin A1C test provides an average of blood sugar control over the preceding two to three months. This test works by measuring the percentage of hemoglobin proteins in red blood cells that have glucose attached to them.
An assessment of cardiovascular health commonly involves a lipid panel, which measures four main components of fat metabolism. Total Cholesterol gives an overall measure of the fatty substances in the blood, but the individual fractions offer more specific information. Low-density lipoprotein (LDL) cholesterol is often associated with the buildup of fatty deposits in artery walls, a process called atherosclerosis.
Conversely, high-density lipoprotein (HDL) cholesterol helps remove excess cholesterol from the bloodstream and transport it back to the liver for processing. The fourth component is triglycerides, which represent fat stored for energy; high levels are linked to an increased risk of heart disease.
Indicators of Liver and Kidney Function
The body’s detoxification and waste management systems are routinely assessed by measuring specific substances related to the liver and kidneys. Kidney function is commonly evaluated using two primary waste products: creatinine and Blood Urea Nitrogen (BUN). Creatinine is a natural byproduct of muscle metabolism, and healthy kidneys filter it efficiently out of the blood. Elevated levels suggest the kidneys are not clearing waste effectively, indicating a reduced filtration efficiency.
BUN is the waste product of protein breakdown, and its measurement provides information on the kidney’s ability to excrete waste. When both creatinine and BUN are high, it often signals that the kidneys are struggling to keep up with their filtration duties. These measurements help determine the estimated glomerular filtration rate, which is a calculation of how much blood the kidneys filter per minute.
Liver health is often checked by measuring the levels of specific enzymes, most notably Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST). These enzymes normally reside inside liver cells but are released into the bloodstream when the cells are damaged or injured. High levels of ALT and AST therefore serve as indicators of cellular damage within the liver.
Another important marker is bilirubin, a yellow pigment that is a byproduct of red blood cell breakdown. The liver is responsible for processing and excreting bilirubin, and an increase in its level in the blood suggests the liver is impaired in this processing ability. Significant increases in bilirubin can lead to jaundice, a yellowing of the skin and eyes.
Assessing Fluid and Electrolyte Balance
A group of tests focuses on electrolytes, which are electrically charged minerals dissolved in the body’s fluids. Sodium, potassium, and chloride are the most commonly measured electrolytes, maintaining fluid balance, hydration, transmitting nerve signals, and regulating muscle contractions, including the heart’s rhythmic beating.
Imbalances in electrolytes (levels too high or too low) can be related to changes in hydration status, dietary habits, or underlying issues with regulatory organs. The measurement of bicarbonate, sometimes reported as total carbon dioxide (CO2), is also included in this panel. Bicarbonate acts as a buffer in the blood, playing a major role in keeping the body’s acid-base balance (pH) within a healthy range.
Understanding Specialized Diagnostic Tests
Some biochemical tests are ordered when symptoms point toward a specific hormonal imbalance or systemic disease, rather than being part of a routine general check-up. Thyroid-Stimulating Hormone (TSH) is one such test, which checks the function of the thyroid gland, often called the body’s metabolic thermostat. TSH is released by the pituitary gland to signal the thyroid gland to produce its hormones, and abnormal levels can indicate an overactive or underactive thyroid.
Another diagnostic marker is uric acid, which is a byproduct formed when the body breaks down purines, substances found in many foods. Elevated levels of uric acid are strongly associated with the condition known as gout, a painful form of inflammatory arthritis. High uric acid can also contribute to the formation of kidney stones.
C-Reactive Protein (CRP) is used as a non-specific indicator of inflammation. This protein is produced by the liver, and its concentration increases rapidly in response to generalized inflammation, infection, or tissue injury. While it does not pinpoint the cause, an elevated CRP level signals that a significant inflammatory process is occurring.