What Can You Learn from a Biochemical Blood Test?

In the world of medicine, biochemical blood tests are a common practice. They’re typically ordered before hospitalization or when a diagnosis needs further clarification. In this article, we’ll explore 10 crucial biochemical markers that doctors often request and break down what valuable insights they can provide.

Understanding Biochemical Blood Tests

Biochemical blood tests encompass a range of 8 to 14 laboratory assessments designed to measure specific chemicals in your blood. These tests enable doctors to gain insights into how your body processes food and energy and to identify potential issues with your internal organs.

It’s worth noting that the exact set of tests within a biochemical study can vary from one laboratory to another. Therefore, when your doctor prescribes a biochemical test, be sure to confirm which specific indicators are included in your assessment.

When Are Biochemical Blood Tests Necessary?

Biochemical blood tests serve three primary purposes:

1. Screening: Screening tests are employed to detect diseases before they manifest noticeable symptoms. This approach is valuable because it allows for early intervention when diseases are more manageable. There are two key biochemical tests suitable for screening purposes:
   • Blood Glucose Analysis: This test helps identify disorders in carbohydrate metabolism, which could potentially lead to type 2 diabetes.
   • Total Cholesterol Analysis: This test aids in determining the risk of cardiovascular diseases.
2. Diagnostic Confirmation: When a doctor requires additional information to confirm or rule out a specific diagnosis, they may prescribe biochemical tests tailored to the situation. These tests are chosen with precision to provide the necessary insights.
3. Treatment Monitoring: Biochemical tests can also help gauge the effectiveness of a treatment regimen. Typically, blood samples are taken at various points during treatment to assess how it impacts the functioning of specific organs. This process helps doctors make informed decisions about ongoing treatment adjustments.

It’s important to emphasize that while biochemical tests can alert doctors to potential issues with substance metabolism or specific organs, they alone cannot pinpoint the exact nature of a problem. Many different medical conditions can lead to deviations from normal laboratory indicators. Therefore, for anything beyond routine check-ups, your doctor will carefully select and interpret the appropriate biochemical tests to ensure accurate diagnosis and treatment evaluation.

How to Prepare for a Blood Biochemistry Test

What type of blood is suitable for conducting biochemical studies?

Biochemistry tests typically require blood samples obtained either from a vein or a finger. However, in most Western auditory laboratories, venous blood is the preferred choice due to its higher accuracy in yielding results. It’s important to note that the actual study doesn’t involve the entire blood sample but focuses solely on its liquid component, which can be either plasma or serum.

Plasma, the liquid portion of blood, is devoid of blood cells such as erythrocytes and leukocytes. On the other hand, serum is quite similar to plasma but lacks fibrinogen, a protein responsible for blood clotting. It’s worth mentioning that the concentration of specific chemical substances can vary between plasma and serum, underscoring the importance of ensuring the appropriate biomaterial is selected when undergoing laboratory analysis—especially when considering the potential need for repeat tests.

How to prepare for a blood analysis?

Glucose and iron levels in your blood are influenced by the food you consume. Right after eating, these levels will be higher than they would be a few hours later. To ensure accurate test results, laboratories worldwide have standardized the practice of measuring glucose and iron levels on an empty stomach. This means that you should refrain from eating for 8 to 12 hours before the analysis. You can still drink, but stick to plain, non-carbonated water.

For tests that are not as affected by food, like those not measuring glucose or serum iron, you can have breakfast before heading to the laboratory. However, avoid sugary treats, fatty foods, tea, and coffee. Opt for a meal like oatmeal with water, an egg, and a slice of rye bread, but skip the bacon and sweet pastries.

Moreover, physical activity can impact the concentration of various chemicals in your blood. Intense exercise can damage muscle cells, releasing creatinine into your bloodstream, which can interfere with the assessment of your kidney health. To ensure accurate test results, avoid strenuous physical activity for at least 24 hours before your analysis and abstain from alcohol for at least 12 hours beforehand.

The concentration of certain substances in your blood can also fluctuate throughout the day. So, if you need to repeat a biochemical analysis multiple times, remember the time of day of the initial test and replicate the conditions. If your first test was in the morning while you were fasting, it would be incorrect to redo the same analysis after a hearty lunch. Instead, come back in the morning on an empty stomach.

Lastly, be aware that nicotine and chewing gum, even if sugar-free, can influence the results of a biochemical analysis. Therefore, avoid chewing gum and refrain from smoking for at least half an hour to an hour before your blood is drawn.

Blood Collection Process for Biochemical Analysis

Collecting blood for a biochemical analysis typically involves drawing it from a vein. When a patient arrives at the healthcare facility, a nurse will request their full name, determine the necessary blood tests, and inquire about any past episodes of fainting during blood collection. If there’s a history of such incidents, the nurse will ensure the patient is seated securely to prevent falls.

Next, the nurse will ask the patient to roll up their sleeve and take a seat. They will then instruct the patient to make a fist while applying a tourniquet just above the elbow. After cleaning the injection site with alcohol, the nurse will gently insert a needle into a vein, attach a vial to the needle, and instruct the patient to relax their arm.

Once the vial is filled, the nurse will release the tourniquet, detach the vial, withdraw the needle, sanitize the puncture site with an alcohol swab, and dress the arm with a bandage. Typically, patients are advised not to strain the arm for about half an hour to minimize the risk of bruising at the puncture site. After this period, the bandage can be removed.

Regarding the turnaround time for test results, it can vary among different laboratories. However, as a general guideline, biochemical analyses usually take between 1 to 3 days to provide results.

How to Interpret Laboratory Test Results

Many individuals believe that if the results of their laboratory tests fall within the specified range of numbers, known as the reference interval, their readings are considered normal. However, it’s important to recognize that “laboratory normal” and “normal results” are not synonymous.

Reference intervals are determined based on data from a large group of healthy individuals. Nevertheless, what is considered typical for a healthy person in the United States may differ significantly from what is typical in places like Nicaragua or Russia. This diversity leads to the absence of universal reference intervals for biochemical analyses.

Different laboratories employ distinct reference intervals: some laboratories calculate them independently, while others rely on scientific literature or reagent instructions. Consequently, the same individual’s biochemical analysis result might fall within the reference interval in one laboratory but exceed it in another.

Furthermore, there are situations where a healthy person’s results surpass the reference interval, while an individual with health issues falls within it. Such variations do not necessarily indicate an error on the part of the laboratory; they may reflect unique characteristics of specific individuals.

To arrive at an accurate diagnosis, a single “abnormal” laboratory test result is insufficient. Doctors must ensure that the result aligns with diagnostic criteria, evaluate other test outcomes, consider the patient’s complaints, and take into account the results of a physical examination. In some cases, they may even request the patient to repeat the analysis to rule out any laboratory errors. Overall, clinical diagnosis is a complex task that requires specialized training.

For this reason, we won’t delve into the specific meanings of individual biochemical test results or provide guidance on what to do if they fall outside the normal range—this responsibility falls squarely on the shoulders of healthcare professionals. Instead, this article will focus on explaining the purpose of the 10 most popular biochemical tests and the information they offer.

Let’s look into each indicator:

• Albumin
• Alanine transaminase and Aspartate transaminase
• Glucose
• Creatinine
• Urea
• Total Protein
• Bilirubin
• Calcium
• Cholesterol

Albumin

What is this? Albumins are a type of protein found in our blood, and they play a crucial role in transporting fatty acids, hormones, and vitamins, as well as maintaining the right pressure in our blood vessels to prevent fluid from leaking into our body tissues.

Typically, doctors measure the concentration of albumin in the blood to assess how well our liver and kidneys are working.

What do the results mean? An elevated blood albumin concentration is quite rare and is usually a sign of dehydration.

A decrease in albumin concentration can be caused by various factors, including:

1. Kidney or heart problems: In conditions like nephrotic syndrome, albumin is lost through urine. With chronic kidney or heart issues, excess fluid can build up in the blood vessels, making it seem like there’s less albumin even if the actual level hasn’t changed.
2. Liver diseases: Conditions like cirrhosis and severe hepatitis can hinder the liver’s ability to produce enough albumin.
3. Inflammation: During inflammation, the body’s immune cells release substances called cytokines, which speed up the breakdown of albumin and make blood vessel walls more permeable. This can cause albumin to leave the blood and enter nearby tissues.

Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST)

Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) are enzymes primarily located within cells, with only trace amounts typically present in the bloodstream. However, when cells are damaged, the concentration of these enzymes in the blood rises. ALT is predominantly found in liver cells, while AST is present in liver, heart, and muscle cells. Physicians often conduct these tests simultaneously to aid in diagnosis.

Interpreting the Results: In healthy individuals, the levels of ALT and AST in the blood are usually quite low. Elevated levels of one or both enzymes suggest cellular damage.

By comparing the levels of ALT and AST, one can discern which organ’s cells have been affected. If ALT remains low while AST is elevated, it is less likely that the liver is the issue; instead, another organ, such as the heart, may be affected. In such cases, additional tests and examinations are usually required to pinpoint the problem.

However, when both AST and ALT levels are elevated, the physician examines their ratio, which provides valuable information.

For instance, if the AST to ALT ratio is less than one, it may indicate non-alcoholic fatty liver disease. Conversely, if the ratio is greater than two, alcoholic liver disease is more likely.

Glucose

Glucose serves as the primary energy source for our bodies, derived from the food we eat and essential for every cell’s function.

By monitoring the concentration of glucose in your bloodstream, you can gain insights into how your body handles glucose intake and whether it has enough energy to function optimally.

Understanding the Results

When blood glucose levels fall too low, it results in a condition known as hypoglycemia. In such cases, the body lacks the energy required for normal daily activities. While some individuals may experience hypoglycemia without noticeable symptoms, most people typically feel unwell as their blood glucose levels drop. Common symptoms include a strong desire to eat, dizziness, weakness, paleness, trembling, and sweating.

If glucose levels plummet to a critical point, the brain doesn’t receive sufficient energy, leading to symptoms like slurred speech and blurred vision. Without prompt restoration of normal glucose levels, unconsciousness or even a coma can occur.

Hypoglycemia usually arises from clear causes like hunger or an overdose of diabetes medication in type 1 or 2 diabetes. However, in certain situations, it may also signal other underlying illnesses, such as heart failure or sepsis, which is a severe blood infection.

Conversely, when there’s an excess of glucose in the blood, and it remains there for an extended period, it leads to hyperglycemia. People often can’t perceive mild but persistent increases in blood glucose levels, which is why many are unaware of the gradual development of type 2 diabetes.

A Closer Look at Glucose Intolerance

Elevated fasting glucose levels may raise suspicion of glucose intolerance. In individuals with this condition, their cells don’t respond effectively to insulin, the hormone responsible for moving glucose from the blood into cells. Despite the absence of noticeable symptoms, those with glucose intolerance face a higher risk of developing type 2 diabetes and cardiovascular diseases compared to those with normal blood glucose levels.

The Good News: Prevention is Possible

Prompt measures, such as dietary adjustments, regular exercise, smoking cessation, and limiting alcohol consumption, can help prevent the development of cardiovascular diseases and type 2 diabetes, even in individuals with glucose intolerance.”

Creatinine

Muscles have their own energy reserve – a chemical compound known as creatine phosphate, which provides a rapid surge of energy during physical activity. When depleted, creatine phosphate transforms into creatinine, a harmless substance that the kidneys eliminate from the body.

Analogous to a urine analysis, a study of creatinine levels evaluates the functionality of the excretory system, primarily focusing on the kidneys.

What do the results signify? Much like urea, creatinine is non-toxic and doesn’t serve any crucial functions in the body, so fluctuations in its concentration in the bloodstream typically go unnoticed by individuals.

Decreases in creatine levels are infrequent, usually occurring during prolonged periods of fasting, which can lead to a reduction in muscle mass.

On the other hand, increases in creatinine concentration are more common. This can occur when an individual frequently consumes meat products. However, it is far more common when kidney function is compromised, preventing the efficient removal of creatinine from the blood.

This can be linked to various factors:

1. Sudden kidney injury or poisoning, in which kidney function deteriorates rapidly. In such cases, blood creatine levels increase swiftly, often within a few days.
2. Chronic kidney diseases, where kidney function gradually declines, as seen in conditions like type 2 diabetes or heart failure. Here, blood creatine levels rise gradually, over weeks or even years.
3. Kidney infections, such as bacterial pyelonephritis. In these instances, creatinine concentration reflects the extent of kidney damage – the higher it is, the more severe the damage.
4. Sometimes, creatinine accumulates if an obstruction, like a urinary bladder stone or a prostate adenoma, hinders the flow of urine.

The only common situation where blood creatinine levels rise unrelated to urinary system issues is associated with hyperthyroidism. In this condition, the thyroid gland produces excessive hormones that accelerate metabolism. Consequently, creatine phosphate in muscles depletes rapidly, causing an elevated blood creatinine concentration.

Other less common reasons for increased creatinine levels, such as pituitary tumors, are not as prevalent.

Urea

When your body breaks down the protein from the food you eat, it creates a harmful substance called ammonia. To rid the body of this ammonia, the liver transforms it into a harmless compound called urea, which is then excreted through urine.

Blood urea analysis helps assess the functioning of your kidneys and liver.

What do the results indicate? Urea itself is not toxic and doesn’t have a significant role in the body, so its presence in the blood doesn’t directly impact your well-being.

If the blood urea level is too low, it typically suggests either a state of malnutrition or liver disorders that impede urea formation. These liver issues might include conditions like hepatitis, cirrhosis, or exposure to toxins.

On the other hand, elevated creatinine levels usually point to kidney problems that hinder the timely excretion of creatinine. This can be related to kidney infections like pyelonephritis or conditions like tuberculosis.

Moreover, disruptions in the flow of urine can also lead to high creatinine levels in the blood. This can occur due to various factors, such as kidney stones or, in men, an enlarged prostate known as prostate adenoma, which can block the urethra.

Furthermore, the concentration of creatinine in the blood can rise for various other reasons, ranging from the use of specific medications to concealed bleeding in the digestive tract, like that which may occur with a stomach ulcer.

Total Protein and Albumin-Globulin (A/G) Ratio

In the realm of medical laboratories, the term “total protein” encompasses all the proteins found in the bloodstream. These primarily include transport proteins like albumin and protective proteins known as immunoglobulins. Albumin is manufactured by the liver, while immune cells are responsible for producing most of the immunoglobulins.

What do the results signify? Alterations in the concentration of total protein don’t always imply underlying health issues. For instance, in individuals who have consumed a significant amount of water or have perspired heavily, the protein levels in the blood remain constant. Nevertheless, the concentration may fluctuate temporarily due to shifts in blood fluid volume. A similar scenario arises after a substantial meal, where the volume of fluid in the blood remains unchanged, but there’s a temporary increase in protein content.

However, on occasion, changes in total protein concentration in the bloodstream can serve as an early indicator of a serious medical condition.

A decrease in the concentration of total protein in the blood can occur when:

1. The body is losing more protein than it produces, as seen in cases of hidden bleeding, prolonged diarrhea, or severe kidney diseases. For instance, in nephrotic syndrome, the kidneys fail to filter and return protein to the bloodstream, causing its loss in urine.
2. The body is unable to generate sufficient protein to meet its requirements, a common occurrence in liver diseases, which is the primary organ responsible for protein synthesis.
3. The concentration of total protein falls within the normal range, but the blood becomes too diluted. In conditions like heart failure, where the heart struggles to pump blood to the kidneys, and chronic kidney diseases, it becomes challenging for the body to eliminate excess fluid. In cases of kidney failure, the kidneys lose their ability to convert excess fluid into urine, resulting in fluid accumulation in the body.

An increase in the concentration of total protein in the blood can occur when:

1. The immune system produces a substantial amount of protective immunoglobulin proteins as a response to a viral or bacterial invasion. In this scenario, an elevated concentration of total protein indicates an acute or chronic infection.
2. The body generates an abundance of abnormal proteins, as observed in relatively rare diseases such as myeloma and lymphoma. In these cases, immune cells produce excessive abnormal protein, known as paraprotein, instead of normal immunoglobulins.
3. The concentration of total protein remains within normal limits, but the body loses a significant amount of fluid. This issue can arise due to excessive vomiting, leading to dehydration.

Total Bilirubin

Bilirubin is a yellow-orange substance that forms when the body breaks down hemoglobin, found in our blood. Once created, it enters the liver where it combines with glucuronic acid, transforming into a less harmful, soluble form.

This soluble bilirubin then travels to the gallbladder, where it mixes with bile – a substance vital for digesting food in the intestine. Within the small intestine, bilirubin undergoes further breakdown by intestinal bacteria. Some of it becomes the harmless urobilin, giving urine its characteristic yellow color, while the rest transforms into stercobilin, contributing to the brown color of feces.

Total Bilirubin is a laboratory test that measures the combined concentration of soluble and insoluble bilirubin in the blood. This test is crucial for assessing the health of the liver and bile ducts.

Interpreting the results: There’s typically a small amount of bilirubin in the blood, which poses no harm when its levels remain low. However, an increase in bilirubin concentration can lead to fatigue and exhaustion. Individuals may also experience digestive issues such as a bitter taste in the mouth, heartburn, nausea, frequent constipation, or diarrhea. When bilirubin concentration rises further, the eyes and skin can take on a yellowish tint, a condition known as jaundice.

Elevated levels of bilirubin in the blood usually signal digestive problems. To pinpoint the specific issue, further analysis of soluble (direct) bilirubin is required. This helps in determining the concentration of insoluble (indirect) bilirubin, achieved by subtracting direct bilirubin results from total bilirubin results.

If total bilirubin levels rise due to increased direct bilirubin, it suggests a bile duct obstruction. When the gallbladder is full, direct bilirubin cannot flow from the blood, causing it to accumulate. This blockage can be caused by factors like gallstones blocking the bile duct.

Conversely, if total bilirubin levels rise due to increased indirect bilirubin, it indicates liver cell damage. In this case, the liver struggles to process bilirubin, possibly due to conditions like cirrhosis, viral or alcoholic hepatitis, or Gilbert’s syndrome. In Gilbert’s syndrome, a hereditary condition, the liver cannot efficiently convert insoluble bilirubin into its soluble form, leading to its accumulation in the bloodstream.

Total Calcium

Calcium is a vital element for your body’s proper functioning. In its solid state, calcium forms the foundation of your bones and teeth. When dissolved in your blood, it serves essential roles, such as muscle contraction, hormone release, and transmission of nerve impulses, among other crucial processes.

Interpreting the Results

Deviations from the normal concentration of calcium in your blood can signal health issues, even if they are slight. More severe deviations can even be life-threatening.

If the level of total calcium in your blood drops, it’s referred to as hypocalcemia. This condition disrupts nerve and muscle function, leading to symptoms like tingling, goosebumps, and muscle spasms. In severe cases, it can result in heart failure.

Hypoparathyroidism is a common cause of low blood calcium levels. This condition arises when the parathyroid glands, which regulate kidney function and control blood calcium levels, don’t produce enough parathyroid hormone.

Another reason for low calcium levels is pseudohypoparathyroidism, where the body produces sufficient parathyroid hormone, but the kidneys become insensitive to it.

A significant deficiency of Vitamin D is the third cause. Vitamin D aids in calcium absorption from food, and its shortage often stems from issues with vitamin absorption, rather than lack of sun exposure or a diet low in fatty fish. Poor dietary habits and limited physical activity can worsen these existing problems.

Kidney disease is the fourth culprit. Healthy kidneys not only maintain calcium levels in the blood but also convert vitamin D into its active form. When this conversion falters, the total calcium level in the blood drops.

Conversely, when calcium levels in the blood rise, it leads to hypercalcemia. Small increases often go unnoticed, but as the concentration climbs, the kidneys and digestive system go into overdrive. This can result in excessive thirst, frequent urination, nausea, vomiting, and, in some cases, constipation due to dehydration. If the blood calcium level exceeds 3.0 mmol/L, it can lead to psychosis, stupor, and even coma.

Hyperparathyroidism, characterized by an overproduction of parathyroid hormone, is the primary cause of elevated blood calcium levels. Vitamin D toxicity, often seen in children given excessive vitamin D doses, is another reason for this condition.

Additionally, high blood calcium levels can be associated with bedridden patients, endocrine gland tumors, hereditary disorders, and various other medical conditions.

Total Cholesterol

Cholesterol is a fatty substance found in the membranes of all cells in your body and plays a vital role in hormone production. Most of the cholesterol your body needs is made by your liver, but you also get some from animal products like eggs and meat.

A cholesterol blood test can provide valuable insights into the health of your heart and blood vessels.

So, what do the results mean? It’s important to note that changes in blood cholesterol levels aren’t something you can feel, but they can impact your overall health, even when your levels are within the normal range.

In some cases, cholesterol levels can drop when people switch to a vegetarian or vegan diet. While some experts see this as harmless, others hold a different view.

Cholesterol is not just important for your heart; it also plays a role in the production of hormones and vitamin D. When cholesterol levels fall below 3.1 millimoles/liter, it may have potential negative effects on brain health, potentially increasing the risk of anxiety and depression. However, this connection is not yet definitively proven.

Low cholesterol levels in your blood could be indicative of chronic conditions affecting the organ responsible for cholesterol production, such as liver cirrhosis, or conditions that disrupt cholesterol absorption, like Crohn’s disease.

Furthermore, since cholesterol is essential for hormone production, its levels can decrease when your body overproduces certain hormones, as seen in hyperthyroidism where the thyroid gland produces excess triiodothyronine and thyroxine.

However, it’s worth noting that low cholesterol levels are relatively uncommon. Most medical professionals are more concerned about the more frequent scenario where cholesterol levels exceed the recommended range because elevated total cholesterol levels increase the risk of developing atherosclerosis.

If specific types of cholesterol increase in your blood, your risk of cardiovascular diseases linked to atherosclerosis also rises. In atherosclerosis, cholesterol plaques form in your arteries, narrowing them. If one of these plaques breaks off, it can lead to a heart attack or stroke.

But it’s crucial to remember that assessing risk solely based on total cholesterol concentration isn’t precise. Total cholesterol is a laboratory measure that encompasses all the cholesterol in your body, and not all of it is harmful. The impact of cholesterol depends largely on the type of carrier proteins produced by the liver.

Dietary fats are absorbed in the small intestine and enter the bloodstream as tiny droplets of fatty acids called chylomicrons. Most of these chylomicrons travel to the liver for processing.

The liver transforms low-density lipoproteins (LDLs) into cholesterol and binds it to a carrier protein, forming very low-density lipoproteins (VLDLs). These VLDLs transport cholesterol from the liver to cells, where it is crucial for building cell membranes.

Within blood vessels, an enzyme releases some cholesterol from certain VLDL complexes, turning them into low-density lipoproteins (LDLs), which also carry cholesterol to cells.

If there are excessive VLDLs and LDLs in the blood, cells can’t handle the cholesterol load, and excess cholesterol ends up deposited in blood vessel walls, a key factor in the development of cholesterol plaques. Due to their association with atherosclerosis risk, these complexes are often termed “bad” cholesterol.

However, the liver also manufactures carrier proteins that remove cholesterol from cells, including those in cholesterol plaques, and transport it back to the liver. These complexes are known as high-density lipoproteins (HDLs). Individuals with high levels of HDLs in their blood have a lower risk of atherosclerosis, earning HDL the label of “good” cholesterol.

In some cases, doctors may recommend a separate blood test to measure triglyceride levels. Triglycerides are fats found in the blood that provide energy to the body. Elevated triglyceride levels can also contribute to the risk of cardiovascular disease, although the exact mechanisms are not fully understood.

Collectively, these five biochemical tests for total cholesterol, HDL, LDL, VLDL, and triglycerides form a lipid profile, which provides a comprehensive assessment of your body’s fat metabolism. However, for individuals in their twenties to mid-thirties with normal cholesterol levels and no heart disease risk factors, a lipid profile is typically unnecessary for self-monitoring.

The U.S. Preventive Services Task Force (USPSTF) recommends lipid profile testing for men over 35, women over 45, and individuals starting from age 20 with specific heart disease risk factors, including high blood pressure, obesity, smoking, excessive alcohol consumption, a sedentary lifestyle, and a diet rich in sugar and fatty foods. The frequency of these tests should be determined by a healthcare professional based on your individual risk factors.