All Medical Procedures

Allergy shots are injections you receive at regular intervals over a period of approximately three to five years to stop or reduce allergy attacks. Allergy shots are a form of treatment called immunotherapy. Each allergy shot contains a tiny amount of the specific substance or substances that trigger your allergic reactions. These are called allergens. Allergy shots contain just enough allergens to stimulate your immune system — but not enough to cause a full-blown allergic reaction.

Over time, your doctor increases the dose of allergens in each of your allergy shots. This helps get your body used to the allergens (desensitization). Your immune system builds up a tolerance to the allergens, causing your allergy symptoms to diminish over time.

During allergy skin tests, your skin is exposed to suspected allergy-causing substances (allergens) and is then observed for signs of an allergic reaction.

Along with your medical history, allergy tests may be able to confirm whether or not a particular substance you touch, breathe or eat is causing symptoms.

A blood pressure test measures the pressure in your arteries as your heart pumps. You might have a blood pressure test as a part of routine doctor's appointment or as a screening for high blood pressure (hypertension). Many people, such as those with high blood pressure, do their own blood pressure tests at home so that they can better track their health.

You may have frequent blood pressure tests if you've been diagnosed with prehypertension, high blood pressure (hypertension) or low blood pressure (hypotension).

The level of C-reactive protein (CRP), which can be measured in your blood, increases when there's inflammation in your body. Your doctor may check your C-reactive protein level treatment for infections or for other medical conditions.

A high-sensitivity C-reactive protein (hs-CRP) test, which is more sensitive than a standard test, also can be used to evaluate your risk of developing coronary artery disease, a condition in which the arteries of your heart are narrowed. Coronary artery disease can eventually lead to a heart attack.

A simple blood test measures C-reactive protein. Some researchers think that treating people with high C-reactive protein levels will lessen their risk of heart attack or stroke.

However, according to the American Heart Association, this test isn't recommended for general screening for heart disease. And it might not be helpful in determining your heart attack risk, depending on your health and lifestyle choices.

Your doctor may use cytochrome P450 tests (CYP450 tests) to help determine how your body processes (metabolizes) a drug. Our bodies contain numerous P450 enzymes to process medications. Because of inherited (genetic) traits which cause variations in these enzymes, medications affect each person differently.

The P450 enzyme with the most variation in different people is the 2D6, which processes many antidepressants and antipsychotic medications. By checking your DNA for certain gene variations, cytochrome P450 tests can offer clues about how your body may respond to a particular antidepressant. Other cytochrome P450 tests are available for other enzymes.

Cytochrome P450 and other genetic tests (genotyping tests) are becoming more common as doctors try to understand why antidepressants help some people and not others. While their use might be increasing, there are limitations.

Hematocrit (he-MAT-uh-krit) is the proportion of your total blood volume that is composed of red blood cells. A hematocrit (Hct) test indicates whether you have too few or too many red blood cells — conditions that can occur as the result of certain diseases. Red blood cells, or erythrocytes (uh-RITH-roe-sites), transport oxygen throughout your body.

A hematocrit test is done using a sample of your blood. A lab technician puts the sample in a device called a centrifuge that spins the blood very quickly in a test tube. This motion separates your blood into three parts: the fluid component (plasma), red blood cells and other blood cells. When the blood is separated, the technician can determine what proportion of the cells are red blood cells. Hematocrit is also called packed-cell volume (PCV).

A hemoglobin test measures the amount of hemoglobin in your blood.

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). Anemia can have many different causes, including vitamin deficiencies, bleeding and chronic diseases.

If a hemoglobin test shows a higher than normal level, there are several potential causes — the blood disorder polycythemia vera, living at a high altitude, smoking, dehydration, burns and excessive vomiting.