Tuesday, January 15, 2008

Lab results we might be interested in.

I started wondering today about what lab results might be of interest to the friendly neighborhood RT so I did some researching and tried to narrow down different tests that could come in handy for information in our area of work. One test that I will not include here is the Arterial Blood Gas (ABG) because if you are a RT this is a common test and you should know this one my now. I will be looking at test that normally nursing and doctors will look at more than us but maybe could give us some insight on the patient.

Lab Results of Interest to Respiratory Therapists

Alpha-1 Antitrypsin: Lungs
An alpha-1 antitrypsin concentration is ordered to help diagnose the cause of early onset emphysema, especially when a person does not have obvious risk factors such as smoking or exposure to lung irritants such as dust and fumes.

Alpha-1 antitrypsin (AAT) is a protein that is produced in the liver and released into the bloodstream. AAT helps to inactivate several enzymes but primarily works to protect the lungs from elastase. Elastase is an enzyme produced by neutrophils and it is part of the body’s normal response to injury and inflammation. Elastase breaks down proteins so that they can be removed and recycled by the body but, if its action is not regulated by AAT, elastase will also begin to break down and damage lung tissue.

Lower levels if AAT indicate onset of Emphysema

AFB Smear and Culture: Lungs
AFB smears and cultures are used to determine whether you have an active Mycobacterium tuberculosis infection, an infection due to another member of the Mycobacterium family, or TB like symptoms due to another cause. They are used to help determine whether the TB is confined to the lungs (pulmonary) or has spread to organs outside the lungs (extrapulmonary).

3 Sputum samples are collected. Positive AFB smears indicate a probable mycobacterial infection. Positive AFB cultures identify the particular mycobacterium causing your symptoms and give your doctor information about how resistant it may be to treatment.

BNP and NT-proBNP: Heart
Either BNP or NT-proBNP may be ordered to help diagnose heart failure and to grade the severity of that heart failure. Heart failure is still often confused with other conditions. BNP and NT-proBNP levels can help doctors differentiate between heart failure and other problems, such as lung disease.

Higher-than-normal results suggest that a person is in heart failure, and the level of BNP or NT-proBNP in the blood is related to the amount or severity of heart failure. Higher levels of BNP or NT-proBNP also may be associated with a worse outlook for the patient.

CK or CPK: Heart
Blood levels of CK rise when muscle or heart cells are injured. The doctor may test for CK if the patient is having chest pain or other signs and symptoms of a heart attack. In the first 4 to 6 hours after a heart attack, the concentration of CK in blood begins to rise. It reaches its highest level in 18 to 24 hours and returns to normal within 2 to 3 days. The amount of CK in blood also rises when skeletal muscles are damaged.

A high CK, or one that goes up from the first to the second or later samples, generally indicates that there has been some damage to the heart or other muscles. It can also indicate that your muscles have experienced heavy use.

CK-MB: heart
CK–MB levels, along with total CK, are tested in people who have chest pain to diagnose whether they have had a heart attack. Since a high total CK could indicate damage to either the heart or other muscles, CK–MB helps to distinguish between these two sources. If the doctor thinks that the patient may have had a heart attack and gives a “clot-dissolving” drug, CK–MB can help the doctor tell if the drug worked. When the clot dissolves, CK–MB tends to rise and fall faster. By measuring CK–MB in blood several times, the doctor can usually tell whether the drug has been effective.

If the value of CK-MB is elevated and the ratio of CK–MB to total CK (relative index) is more than 2.5–3, it is likely that the heart was damaged. A high CK with a relative index below this value suggests that skeletal muscles were damaged.

Sometimes persons who are having trouble breathing have to use their chest muscles. Chest muscles have more CK–MB than other muscles, which would raise the amount of CK–MB in the blood.

Electrolytes: fluid retention
Electrolytes are electrically charged minerals that are found in body tissues and blood in the form of dissolved salts. They help move nutrients into and wastes out of the body’s cells, maintain a healthy water balance, and help stabilize the body’s pH level. The electrolyte panel measures the main electrolytes in the body: sodium (Na+), potassium (K+), chloride (Cl-), and carbon dioxide (total CO2).

The doctor will look at the overall balance but is especially concerned with your sodium and potassium levels. People whose kidneys are not functioning properly, for example, may retain excess fluid in the body, diluting the sodium and chloride so that they fall below normal concentrations. Those who experience severe fluid loss may show an increase in potassium, sodium, and chloride. Some forms of heart disease, muscle and nerve problems, and diabetes may also have one or more abnormal electrolytes.

Hemoglobin: Lungs
This test measures the amount of hemoglobin, a protein that is found in red blood cells, and is a good indication of your blood’s ability to carry oxygen throughout your body. Hemoglobin carries oxygen to cells from the lungs.

Normal values in an adult are 12 to 18 grams per deciliter (100 milliliters) of blood. Above-normal hemoglobin levels may be the result of dehydration, excess production of red blood cells in the bone marrow, severe lung disease, or several other conditions.

Heavy smokers have higher hemoglobin levels than nonsmokers and living in high altitudes increases hemoglobin values due to an increase in the number of red blood cells. Your body produces more red blood cells in response to the decreased oxygen available at these heights.

Troponin: Heart
This test measures the concentration of cardiac-specific troponin in your blood. Troponin is a family of proteins found in skeletal and heart muscle fibers; it helps muscles contract. There are three forms of troponin: C, I, and T. Cardiac troponin I and T are different enough from the troponin I and T found in skeletal muscle that they can be specifically tested for. These types of troponin are normally present in very small quantities in the blood. When there is damage to heart muscle cells, cardiac troponin I and T are released into circulation. The more damage there is, the greater the concentration of troponin I and T.

When a patient has a heart attack, levels of troponin can become elevated in the blood within 3 or 4 hours after injury and may remain elevated for 10 to 14 days.

Normally, troponin levels are very low; even slight elevations can indicate some degree of damage to the heart. When the patient has significantly elevated troponin concentrations and other clinical signs, such as an abnormal ECG then it is likely the patient has had a heart attack. If CK and CK-MB, and myoglobin concentrations are normal but troponin levels are increased, then it is likely that either a lesser degree of heart injury is present or that the injury took place more than 24 hours in the past. If the first troponin performed is normal but subsequent (6 hour and 12 hour samples) troponin tests are increased, then the heart injury likely occurred within a couple of hours prior to the first test and had not had time to increase. When a CK test is elevated but a CK-MB (which is more heart-specific than CK) and troponin test are normal, then it is likely that whatever symptoms are present are due to another cause, such as skeletal muscle injury. When a patient with chest pain and/or known stable angina has normal troponin, CK, and CK-MB concentrations, then it is likely that their heart has not been injured.

Well there you have it some different lab test that could give you more insight on your patients condition. If anyone happens to know of any other tests that could be of help feel free to post a comment and I will at it in here.

Most information was found at Lab Tests Online, along with some information from other sites.

Take care and keep em breathing.


Freadom said...

Very good idea. About a year ago, before I discovered blogging, I created a sheet with all these and more on it for myself and my co-workers. I think it's very good to obtain an overall picture of your patient.

Djanvk said...

Could you post that list? Maybe in a printable form, that would be good reference

Freadom said...

I will. How do I do it in a printable form. That's something I'd love to know how to do. Any ideas?

Djanvk said...

You could either put it in a PDF file or a Word file to download possibly.

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