Testing Knowledge
Test Directory
Source-backed test guides: what each test is for, how it is performed, its limitations, and which reviewed products serve it. Personal health questions are answered with knowledge and preparation guidance — not supplier sales.
Opioid Testing
Opioid testing looks for opioids in a sample of your urine (pee), blood, saliva (spit), hair, or sweat.
Nitrites in Urine
A urinalysis test checks for different cells, chemicals, and other substances in a sample of your urine (pee). This includes checking for nitrites. Nitrites in your urine may be a sign of a urinary tract infection (UTI).
Natriuretic Peptide Tests (BNP, NT-proBNP)
Natriuretic peptides are proteins that your heart and blood vessels make. Natriuretic peptide tests measure the amount of these proteins in a sample of your blood. They are mainly used to help confirm or rule out heart failure in people who have symptoms.
Myasthenia Gravis Tests
Myasthenia gravis (MG) tests are used to diagnose MG, a chronic (long-lasting) autoimmune disease that causes weakness in muscles throughout your body. In autoimmune diseases, your immune system mistakenly attacks the healthy cells of your organs and tissues. If you have MG, your immune system makes antibodies that block or change the connection between your nerves and muscles.
MTHFR Gene Test
An MTHFR gene test checks a sample of your blood for two very common changes in a gene called MTHFR . Changes in your genes are also called gene variants or mutations.
MRSA Tests
A MRSA test looks for MRSA bacteria in a sample of fluid or tissue from your body. The sample is often taken from your nose or a wound. MRSA stands for methicillin-resistant Staphylococcus aureus . It is a type of staph bacteria.
MPV Blood Test
MPV stands for mean platelet volume. Platelets (also called thrombocytes) are small blood cells that stick together to make blood clots that stop or slow bleeding when you have a cut or injury. Platelets are made in your bone marrow.
Microalbumin Creatinine Ratio
A microalbumin creatinine ratio urine test checks the levels of the protein albumin in your urine (pee). Abnormal amounts of this protein may be an early sign of kidney disease .
Methylmalonic Acid (MMA) Test
This test measures the amount of methylmalonic acid (MMA) in your blood or urine. MMA is a substance made in small amounts when you digest protein. MMA is needed for metabolism, which is the process that your body uses to change food into energy.
Meningococcal Disease Tests
Meningococcal disease is the name for any infection caused by meningococcal bacteria (called Neisseria meningitidis ). Meningococcal disease tests look for these bacteria in your blood or cerebrospinal fluid (CSF), the fluid in spaces around your brain and spinal cord.
MCV (Mean Corpuscular Volume)
MCV stands for mean corpuscular volume. An MCV blood test measures the average size of your red blood cells.
Malaria Tests
Malaria tests look for signs of a malaria infection in a sample of your blood. These infections are caused by malaria parasites , which are tiny single-celled life forms. There are several types of these parasites.
Magnesium Blood Test
A magnesium blood test measures the amount of magnesium in a sample of your blood. Magnesium is a mineral that you get from many kinds of foods you eat. Some examples include nuts, seeds, beans, fortified breakfast cereals, green leafy vegetables, and milk.
Lyme Disease Tests
Lyme disease is an infection caused by bacteria you get from tick bites . Lyme disease tests look for signs of infection in a sample of your blood or cerebrospinal fluid (CSF). CSF is a clear liquid that flows in and around your brain and spinal cord. The test checks your sample for antibodies that your immune system makes to fight the bacteria that cause Lyme disease.
Luteinizing Hormone (LH) Levels Test
This test measures the level of luteinizing hormone (LH). A hormone is a chemical messenger in your bloodstream that controls the actions of certain cells or organs. LH is usually measured in a sample of your blood. But in certain cases, it may be measured in urine (pee).
Liver Function Tests
Liver function tests (also called a liver panel) use a sample of your blood to measure several substances made by your liver.
Lipoprotein (a) Blood Test
A lipoprotein (a) test measures the level of lipoprotein (a) in your blood. A high level of lipoprotein (a) may mean you have a high risk for heart disease and stroke .
Lipase Tests
A lipase test measures the level of lipase in your blood. Lipase helps your body digest fats . It's a type of digestive enzyme. An enzyme is a protein that speeds up certain chemical reactions in your body. Most of your lipase is made in your pancreas, an organ located behind the lower part of your stomach. Lipase is also made in your salivary (spit) glands and in your stomach.
Legionella Tests
Legionella is a type of bacteria . When it affects your lungs, it can cause a severe form of pneumonia known as Legionnaires' disease . Legionella tests look for these bacteria in urine, sputum, or in some cases in lung tissue. A blood test may be done to check if you have been exposed to the bacteria, but it cannot diagnose a Legionella infection.
Lactate Test
This test measures the level of lactate, also called lactic acid, in a sample of your blood. In certain cases, cerebrospinal fluid (CSF) may be used. Normally, you have low levels of lactate in your blood and CSF. High levels of lactate may be a sign of a wide variety of medical conditions.
Lactate Dehydrogenase (LDH) Test
A lactate dehydrogenase (LDH) test usually measures the level of lactate dehydrogenase (LDH) in a sample of your blood. In certain cases, LDH levels are measured in samples of other body fluids. This includes testing fluid from the spine ( cerebrospinal fluid ), the belly ( peritoneal fluid ), and the chest ( pleural fluid ).
Lactate Dehydrogenase (LDH) Isoenzymes Test
This test measures lactate dehydrogenase (LDH) isoenzymes in a sample of your blood. It's a general test that can help find out if you have tissue damage from disease or injury. It can also help show which organs and other tissues are likely to be damaged. But an LDH isoenzymes test alone cannot diagnose what's causing the damage.
Kidney Stone Analysis
Kidney stones are small, pebble-like pieces of material that form in one or both of your kidneys. Your kidneys are two bean-shaped organs just below your rib cage. They keep your body's balance of water, minerals, and salts by removing waste to make urine (pee). Kidney stones form when you have high levels of some minerals or salts in your urine (pee). Many things may increase your risk of kidney stones. These can include your diet, some health conditions, and some supplements or medicines.
Ketones in Urine
A ketones in urine test measures ketone levels in your urine. Normally, the cells in your body use blood glucose (also called blood sugar) for energy. It comes from the food you eat. Your body breaks down most of that food into glucose and releases it into your bloodstream. If your cells can't get enough glucose, your body breaks down fat for energy instead. This produces an acid called ketones, which can build up in your blood and urine.