Urea is produced as a waste product of protein metabolism and is readily found within the blood. The kidneys are responsible for filtering this urea out of the blood into the urine. Consequently, a urea test is commonly performed to determine how well the kidneys are functioning, with elevated levels of urea in the blood suggesting impaired kidney function. However, consuming large amounts of protein or the presence of dehydration may also result in elevated levels of urea. In comparison, low amounts of urea may indicate liver failure, malnutrition, excessive hydration or the consumption of a low protein diet.

Creatinine is a breakdown product of creatine phosphate that is found in muscle. Serum creatinine is an important indicator of renal health because it is an easily measured by-product of muscle metabolism that is excreted unchanged by the kidneys. Causes of elevated serum creatinine can be attributed to by a variety of lifestyle factors including, consuming creatine supplements, high amounts of animal protein, or performing high intensity exercise. Whilst other causes include impaired kidney function. On the other hand, low serum creatinine can be an indication of the kidneys functioning efficiently. In addition, a low protein diet or reduced muscle mass may also result in a low reading.

The estimated glomerular filtration rate is one of the best tests used to assess how well your kidneys are functioning. The kidneys are composed of thousands of glomeruli which act as tiny filters that are capable of filtering waste from the blood. The eGFR is an estimation of how much blood passes through these glomeruli with each passing minute and can be calculated based on blood creatinine levels, gender, age and weight. A high eGFR indicates optimal functioning of the kidneys. In contrast, a low value for eGFR means your kidneys may not be working to their full potential and can be a sign of kidney disease. eGFR can also be a useful tool in determining the stage of kidney disease which is important in identifying the best treatment for you. Early detection of kidney disease means there could be a better chance of slowing or stopping the progression of the disease. A low eGFR may also be observed in individuals from certain ethnic backgrounds or those with increased muscle mass, in which case impaired kidney function may not be the case.

The level of alkaline phosphatase in the blood is checked through the ALP test, which is often part of routine blood tests. Alkaline phosphatase (ALP) is an enzyme found mainly in the liver and bones. The levels of this enzyme in the blood is dependent on several factors such as age, sex and blood type. Elevated levels of ALP in the blood could indicate issues relating to the liver, gall bladder or bones. As ALP is non specific, ALP is normally checked in addition to other liver function tests to determine whether the damage has occurred to the liver or the bones. Blood levels of ALP also increase two to four times during pregnancy and in growing teenagers.

Alanine transferase (ALT) is an enzyme that is produced by the liver. Elevated ALT can be indicative of inflammation of the liver characteristic of liver damage which may be caused by drugs, alcohol or viruses (hepatitis). High intensity exercise can also result in elevated levels of ALT.

AST is an enzyme your liver makes. Other organs, like your heart, kidneys, brain, and muscles, also make smaller amounts. AST is also called SGOT (serum glutamic-oxaloacetic transaminase).

Normally, AST levels in your blood are low. When your liver is damaged, it puts more AST into your blood, and your levels rise.

A high AST level is a sign of liver damage, but it can also mean you have damage to another organ that makes it, like your heart or kidneys.

Gamma GT is an enzyme found within the liver and is typically raised following diseases affecting this tissue or the bile ducts. Elevated ALP on its own cannot distinguish between liver or bone damage, however, when this value is combined with an elevated levels of gamma GT it is indicative of liver disease. Gamma GT can also be used to diagnose alcohol abuse as it is typically raised in the majority of long term drinkers.

Bilirubin is a yellow compound that is produced during the break down of haemoglobin. This is a necessary process in the body's clearance of waste products that arise from the destruction of aged or abnormal red blood cells. Bilirubin is removed from the body via the liver and excreted in bile and urine. The accumulation of bilirubin can result in jaundice which involves the yellowing discoloration of the whites of the eyes in addition to the skin. Elevated levels may indicate the livers inability to remove it from the blood and therefore can be a sign of liver damage. Certain diseases such as Gilberts syndrome or a blocked bile duct can also result in elevated levels of bilirubin.

Total Protein describes the total sum of globulin and albumin combined. Levels outside of the normal range can be indicative of kidney or liver disorders. Other causes of abnormal levels include malnutrition.

Albumin is primarily produced by the liver and is an important protein in preventing blood from leaking out of blood vessels. Other functions of albumin range from transporting substances such as medications through the blood to playing a role in the growth and repair of tissues. Elevated levels of albumin are typically caused by dehydration. In contrast, low levels may be indicative of liver disease, inflammation or malnutrition. Levels may also be raised in conditions such as diabetes.

Globulin may be produced by the immune system or the liver and consist of several different proteins with varying roles. For instance, some globulins are capable of binding to haemoglobin while others may be involved in the transport of substances like iron and in fighting infection.

Creatine kinase (CK) is an enzyme that exists in various cell types and tissues but found in especially high amounts in the muscle. High levels of CK in the blood can indicate damage to the muscles as CK leaks out of the tissue. Following damage and trauma to the muscles, CK levels will drastically rise, with levels subsiding to normal once the damage is repaired. Individuals with greater muscle mass typically have higher levels of CK.

Transferrin is produced by the liver and is a major protein that regulates the absorption and transportation of iron into and throughout the blood and body respectively. High levels of transferrin saturation are indicative of iron overload whilst low levels may coincide with iron deficiency.

A total iron-binding capacity (TIBC) test measures the blood's ability to attach itself to iron and transport it around the body. Individuals with iron deficiency will have low levels of iron but a raised TIBC. In comparison, those that have possess too much iron, for instance, in patients with iron overload syndrome, iron will be elevated but TIBC will be reduced or normal.

Measuring the amount of iron present in the blood is important in the diagnosis of conditions such as iron deficiency anaemia caused by a lack of iron to haemochromatosis which is caused by an overload of iron. Common symptoms of both elevated and reduced levels of iron include; muscle weakness, difficulty concentrating and fatigue. Other causes of reduced iron besides anaemia can be due to general blood loss. In contrast, a raised result can be indicative of an iron overload syndrome which may be the result of an inherited condition that results in the body storing too much iron, or the excessive consumption of iron supplements.

Ferritin is a protein that stores iron and releases it in a controlled fashion. In humans, it acts as a buffer against iron deficiency and iron overload. Plasma ferritin is also an indirect marker of the total amount of iron stored in the body, hence serum ferritin is used as a diagnostic test for iron-deficiency anaemia. Low levels are indicative of anaemia and may be caused by events such as excessive bleeding or lack of iron within the diet. In contrast, elevated ferritin levels could indicate iron overload syndrome or liver damage.

Triglycerides are a type of fat (lipid) that is found within the blood. After a meal, the body converts any calories it doesn't need to use right away into triglycerides. These are then transported to cells where they are stored as fat. Later, the production of hormones can stimulate the release of triglycerides which can be used for energy between meals. The regular overconsumption of greater than those burned may result in hypertriglyceridemia, a condition in which the level of triglycerides are elevated. This can be a risk factor for microvascular disease which affects the tiny blood vessels around the heart. 

Cholesterol is an essential body fat (lipid) that is predominantly derived from the foods we consume, though, is also produced by the liver. Cholesterol is an important component of cell membranes and is also a precursor molecule to a variety of essential hormones. Individuals with high levels of cholesterol in the body are at a significantly increased risk for developing heart disease. However, total cholesterol is a sum of both good (HDL) and bad (LDL) cholesterol therefore, it is necessary to investigate whether the rise in total cholesterol is caused by a high proportion of HDL or LDL as HDL can in fact exhibit protective effects against heart disease.

HDL (high density lipoprotein) cholesterol is often referred to as the "good" cholesterol due to its ability to pick up other forms of excess cholesterol present in the blood and transport this back to the liver where it is broken down and removed from the body. Individuals with increased levels of HDL cholesterol have been found to be associated with a lower risk of developing heart disease.

LDL cholesterol (low density lipoprotein) also known as the "bad" cholesterol is responsible for transporting triglycerides, other fats and other cholesterol to a variety of tissues located throughout the body. Excessive amounts of LDL in the body as a result of the overconsumption of certain foods, can result in fatty deposits accumulating on the walls of the artery. This can subsequently result in the development of atherosclerosis and is associated with an increased risk of heart disease. 

Measurements of Non-HDL cholesterol are important in establishing the total amount of cholesterol present in the blood that serve a non-protective role for the body and are potentially harmful. The value is calculated by subtracting an individuals HDL cholesterol result from the value of total cholesterol. As the value includes a total of all the forms of potentially damaging cholesterol and not just LDL alone, it is considered to be a greater biomarker for cardiovascular risk.

HDL (high density lipoprotein) cholesterol is often referred to as the "good" cholesterol due to its ability to pick up other forms of excess cholesterol present in the blood and transport this back to the liver where it is broken down and removed from the body. Individuals with increased levels of HDL cholesterol have been found to be associated with a lower risk of developing heart disease.

Uric acid is a waste product that is produced from the metabolism and breakdown of protein. Increased protein digestion may result in significant amounts of uric acid being deposited as crystals in the tissues of the body. When this process occurs in the joints, it can result in a condition known as gout which can lead to severe pain.

SHBG is a protein that is produced by your liver and is able to bind tightly with three main sex hormones (dihydrotestosterone (DHT), testosterone and Estrogen). These hormones can be found in your blood in an unbound, free form in both women and men. However, when SHBG binds to them they become bound and unavailable to the cells of your body, therefore, SHBG can influence the amount of these free hormones that is available to your tissues. A high value for SHBG can indicate a lack of testosterone or oestrogen available to your tissues whilst a low SHBG value can indicate an excess amount of these hormones available. Causes for changes in the level of SHBG other than sex and age include hyperthyroidism and liver disease.

Luteinizing hormone (LH) is produced in the anterior pituitary gland and plays an important role in regulating the function of the reproductive tissues which include the ovaries in females and testes in males.

In women, during the first half of a typical menstrual cycle (roughly weeks one to two), LH is required to stimulate the ovarian follicles that are located in the ovaries to produce the female sex hormone oestradiol. LH naturally rises at around day 14 of a women's cycle and this surge is vital in stimulating the ovaries to release an egg during ovulation. Given fertilization occurs, LH also stimulates the corpus luteum, which secretes progesterone that is essential for sustaining pregnancy.

For men, LH plays a key role in stimulating the production of the main male sex hormone (testosterone) from Leydig cells present in the testes. Further to this, testosterone is then able to stimulate the production of sperm as well as contribute to the development of a set of characteristic traits which range from increased muscle and bone mass to the degree of bodily hair present.

LH also stimulates the production of testosterone in females. Consistently raised LH in women is often associated with polycystic ovary syndrome in which excessive amounts of testosterone are produced as a result of elevated LH. In contrast, low levels of LH may result in the halt of ovulation.

Low levels of LH may be a cause of infertility in both men and women due to levels being insufficient in stimulating sperm production or the ovulation process.

Oestradiol is an important steroid hormone that can be found in both men and women. In women, oestradiol is mainly produced by the ovaries and plays a key role in the maturation and maintenance of the female reproductive system.

In comparison, men produce considerably lower amounts of oestradiol. This is mainly produced by the testes where some testosterone is converted into oestradiol which is a vital component for the production of sperm. Oestradiol may also be produced to lesser extent by fat tissue in both men and women. Elevated levels of oestradiol may lead to a host of conditions ranging from depression to acne. A raised result has also been found to be associated with an increased risk of breast and uterine cancer. In contrast, low levels may affect the menstrual cycle, fertility, mental health or even lead to osteoporosis. In men, increased oestradiol can lead to infertility, loss of libido or the development of breast tissue. Levels may rise due to the accumulation of excessive fat tissue that secretes oestradiol.

Follicle-stimulating hormone (FSH) is produced by pituitary gland and plays a key role in the reproductive system of both men and women. In women, FSH regulates the growth of ovarian follicles which secrete progesterone and Estrogen that are required for key events during the menstrual cycle. In men, FSH plays a key role in the development of the testes as well as the production of sperm.

Testosterone is a male sex hormone that is produced in the testicles of men and to a lesser extent in the ovaries of women. In men, testosterone plays an important role in the development of the male reproductive tissues including the prostate and testes. Testosterone is responsible for a variety of traits which can range from; increasing the mass of bone and muscle to influencing the growth of hair on the body. Therefore, men with lower levels of testosterone may encounter a reduction in these traits, whilst women with raised testosterone may encounter an increase in these traits. Raised testosterone is commonly observed in women with polycystic ovaries syndrome in which increased body hair, acne or a deepened voice may be characteristic. In men, abnormally high testosterone levels may be a result from anabolic steroid use. Other possible causes of high testosterone levels in males include tumors in the adrenal glands or testicles which is rare.

Prolactin is a hormone which is produced in the pituitary gland in both men and women. Prolactin can also influence the levels of other important hormones such as Estrogen and testosterone in both sexes. In women, prolactin stimulates the production of milk following the birth of a child. Consequently, levels are characteristically high in pregnant and breastfeeding women. However, elevated prolactin levels in both men and women that are not pregnant or breastfeeding is a condition known as hyperprolactinemia and may lead to loss of libido, bone density loss and potential infertility. In women in particular, elevated prolactin may also lead to other issues such as vaginal dryness or disruptions to the normal menstrual cycle subsequently leading to irregular periods. In comparison, symptoms specific to men in response to high levels of prolactin may include breast enlargement or erectile dysfunction

The Free Androgen Index (FAI) is a ratio used to determine the amount of free androgen hormones within the blood and whether this is within the normal range. Testosterone readily binds to proteins within the blood such as SHBG, though it can also be found in a free, unbound state. The FAI ratio is based on measurements of testosterone present in your blood in comparison to the total amount of testosterone plus SHBG in your body. In women, an elevated value for FAI could indicate polycystic ovary syndrome. In men, a low value could be indicative of a reduced availability of testosterone which may be associated to symptoms including loss of muscle mass, libido and erectile dysfunction.

Testosterone is a male sex hormone that is produced in the testicles of men and to a lesser extent in the ovaries of women. Testosterone can be found bound to protien where it is unable to be used or unbound free in the blood. This test measures the amounts of free testosterone in the blood which can be used in the body. In men, testosterone plays an important role in the development of the male reproductive tissues including the prostate and testes. Testosterone is responsible for a variety of traits which can range from; increasing the mass of bone and muscle to influencing the growth of hair on the body. Therefore, men with lower levels of testosterone may encounter a reduction in these traits, whilst women with raised testosterone may encounter an increase in these traits. Raised testosterone is commonly observed in women with polycystic ovaries syndrome in which increased body hair, acne or a deepened voice may be characteristic. In men, abnormally high testosterone levels may be a result from anabolic steroid use. Other possible causes of high testosterone levels in males include tumors in the adrenal glands or testicles which is rare.

The purpose of this test is to measure the amounts of free thyroxine (T4) that is present within the blood. T4 is a one of two hormones that is secreted by the thyroid gland. Therefore, a high result may be associated with an individual with an overactive thyroid as more T4 is produced then normal. In contrast, a lower than normal result may arise if an individual has an underactive thyroid.

The purpose of this test is to measure the amounts of free thyroxine (T3) that is present within the blood. T3 is a one of two hormones that is secreted by the thyroid gland (the other being T4). Therefore, a high result may be associated with an individual with an overactive thyroid (hyperthyroidism) as more T3 is produced then normal.

Thyroid Stimulating Hormone (TSH) is produced by the pituitary gland and acts to increase the functioning of the thyroid gland, This stimulation in turn encourages the production of triiodothyronine (T3) and thyroxine (T4) by the thyroid. Elevated TSH may be indicative of an underactive thyroid, In comparison, reduced TSH may be associated with an overactive thyroid.

MPV stands for mean platelet volume. Platelets are small blood cells that are essential for blood clotting, the process that helps you stop bleeding after an injury. An MPV blood test measures the average size of your platelets. The test can help diagnose bleeding disorders and diseases of the bone marrow.

A platelet count test measures the number of platelets in your blood. A lower than normal platelet count is called thrombocytopenia. This condition can cause you to bleed too much after a cut or other injury that causes bleeding. A higher than normal platelet count is called thrombocytosis.

A hematocrit (he-MAT-uh-krit) test measures the proportion of red blood cells in your blood. Red blood cells carry oxygen throughout your body. Having too few or too many red blood cells can be a sign of certain diseases. The hematocrit test, also known as a packed-cell volume (PCV) test, is a simple blood test.

Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs. If a hemoglobin test reveals that your hemoglobin level is lower than normal, it means you have a low red blood cell count (anemia).

MCH is short for "mean corpuscular hemoglobin." It's the average amount in each of your red blood cells of a protein called hemoglobin, which carries oxygen around your body. It's possible you'll learn about MCH when you get a blood test called a CBC (complete blood count).

MCHC is short for mean corpuscular hemoglobin concentration. Simply put, this is the average concentration of hemoglobin inside a group of red blood cells. MCHC refers to the average concentration of hemoglobin in a given volume of red blood cells. A normal MCHC level for an adult is 31-37 grams per deciliter (g/dL).

MCV stands for mean corpuscular volume. An MCV blood test measures the average size of your red blood cells. Red blood cells carry oxygen from your lungs to every cell in your body. Your cells need oxygen to grow, reproduce, and stay healthy.

The RDW blood test is often part of a complete blood count (CBC), a test that measures many different parts of your blood, including red cells. The RDW test is commonly used to help diagnose anemia, a condition in which your red blood cells can't carry enough oxygen to the rest of your body.

A red blood cell (RBC) count is almost always part of a complete blood count, a group of tests that measure many different parts and features of your blood. The RBC measurement is used to help diagnose red blood cell disorders, such as anemia, a condition in which your body does not make enough healthy red blood cells.

A white blood cell (WBC) count is a test that measures the number of white blood cells in your body. It may also be called a leukocyte test. This test is often included with a complete blood count (CBC), which is commonly used to screen for different conditions that may affect your overall health.

Basophils are white blood cells from the bone marrow that play a role in keeping the immune system functioning correctly. Doctors may order basophil level tests to help diagnose certain health problems. If basophil levels are low, this may be a sign of an allergic reaction or another condition.

An absolute eosinophil count is a blood test that measures the number of one type of white blood cells called eosinophils. Eosinophils become active when you have certain allergic diseases, infections, and other medical conditions. Blood is comprised of red blood cells, platelets, and various white blood cells.

Blood test that counts how many lymphocytes are in the blood as a B and T cell screen. This test measures the levels of the main types of white blood cells in the body. Lymphocyte count is one part of a complete blood count (CBC), which is a larger whole blood test.

Monocytes are measured with a blood test called a white blood count (WBC) differential. It's often part of a complete blood count (CBC). A CBC does tests on the red blood cells, white blood cells, and platelets in your blood. A CBC is a routine part of an annual physical exam.

An absolute neutrophil count identifies how many neutrophils are in a sample of your blood. The normal range of neutrophils in a healthy adult is between 2,500 and 7,000 neutrophils per microliter of blood. Any number above 7,000 or below 2,500 puts you at risk of a neutrophil condition.

Interestingly enough, vitamin D is in fact a hormone that is produced by the body and requires exposure to sunlight for activation. In addition. it can be found in certain foods such as egg yolks, fish and fortified dairy and grain products. Vitamin D is an essential component required for maintaining bone strength due to its role in aiding the intestines ability to absorb calcium. Low levels of vitamin D may be associated with secondary low bone mineral density and hyperparathyroidism. Consequently, these patients have a greater risk of suffering fractures and osteoporosis. Other conditions such as rickets and osteocalcin may also develop as a result of continued vitamin D deficiency over a long period of time.

Vitamin B-12 is an important vitamin that is involved in several processes ranging from the production of red blood cells to aiding in the correct functioning of the nervous system. Consequently, prolonged vitamin B12 deficiency can result in anaemia or nerve damage respectively. In contrast, elevated levels of vitamin B12 can be an indication of a liver or blood disorder. The most common cause of raised vitamin B12 is due to over supplementation.

Folate is a type of B vitamin that is involved in several processes from the production of red blood cells to the production and repair of DNA. Individuals mainly receive folate from their diet therefore, a lack of folate within the diet can result in folate deficiency. Low levels may also be indicative of anaemia.

C-Reactive Protein (CRP) is a protein that increases in response to inflammation detected within the body - though it cannot be used to identify the exact location of where this inflammation is occurring. On the other hand, high Sensitivity CRP (hs-CRP) is used to detect low-level inflammation and can give more of an indication of the location of the inflammation as this type has been found to be associated with damaged blood vessels. Damage to blood vessels can increase an individuals likelihood of suffering a stroke or heart attack. Therefore, an elevated hs-CRP may be considered a risk factor for cardio-vascular disease.

When glucose attaches itself to the haemoglobin present in your red blood cells it produces glycosylated haemoglobin also known as HbA1c. HbA1c can be used to give an indication of the levels of glucose present in the blood over a three month period as red blood cells only live for around 12 weeks. Measuring HbA1c is one of the most important steps in the diagnosis of type 2 diabetes. In addition, it also provides a good indication of how well blood sugar levels are being controlled during this period in individuals that may have already been diagnosed with diabetes.

Thyroglobulin (TG) is a protein that is found within the thyroid gland where it is required for the production of the hormones triiodothyronine (T3) and thyroxine (T4). This test evaluates the levels of antibodies against TG that are present within the blood. As antibodies against TG (TGAb) typically only arise following inflammation or attack of the thyroid by the body's immune system, elevated levels may be indicative of an autoimmune disorder that may result in the impairment of normal thyroid functioning.

Thyroid peroxidase (TPO) is an enzyme that can be found within the thyroid gland where it is involved in the conversion of thyroxine (T4) to triiodothyronine (T3). This test evaluates the levels of antibodies against TPO that are present. A high value of antibodies against TPO (TPOAb) can indicate the body has mounted an immune response against the thyroid gland leading to its attack and potential damage. This may be indicative of an autoimmune disorder where the functioning of the thyroid may be impaired. Examples of such autoimmune disorders include Hashimoto's disease which is associated with an underactive thyroid and Graves disease which is associated with an overactive thyroid.

DHEA-S (dehydroepiandrosterone sulphate) is a male hormone that is produced in the adrenal glands and is readily converted into testosterone in the body. Testosterone is responsible for a variety of traits which can range from; increasing the mass of bone and muscle to influencing the growth of hair on the body. In women, DHEA-S may be raised in individuals with polycystic ovary syndrome. High levels of DHEA-S may also be a contributing factor to excessive bodily hair growth (hirsutism) in women due to increased amounts of DHEA-S being converted to testosterone. In both men and women, elevated DHEA-S may be caused by Cushing's Disease or an overactive adrenal gland that may be caused by an adrenal tumour. Whilst low levels of DHEA-S may also be caused by impaired functioning of the adrenal glands that can result in symptoms including loss of libido or issues with fertility.

Cortisol is a hormone that is produced by the adrenal glands. It is commonly referred to as a stress hormone due to its ability to trigger and fuel the "fight-or-flight" response. However, cortisol also plays key roles in several other processes within the body such as regulating blood pressure and your circadian rhythm. Reduced levels of cortisol (Addison's disease) may result in low blood pressure and fatigue. Whilst high levels of cortisol may be characteristic of Cushing's syndrome and can result in the growth of excessive hair on the body in women or erectile dysfunction in men. In both women and men it can result in a sudden increase in weight, especially focused on the midriff area.