How to Understand Urinalysis, Diagnostic Blood Tests

Do you know as much as you should about urine tests and diagnostic blood tests? If you don't, you will be unable to spot any errors that could lead to a misdiagnosis and inappropriate treatments.

OK, let's look at laboratory tests

The complete blood count known as CBC measures the number of cells in your blood. This is an important number as many abnormalities and diseases can cause an abnormal blood count such as some cancers, blood disorders and infections.

A urinalysisevaluates the chemistry and appearance of your urine. Abnormalities here can indicate some types of cancer, diabetes, kidney disease, or urinary tract infections.

You may well be aware of the above but what you may not know is that some people are what pathologists call 'outliers'. Basically, you may be healthy but one or other of the tests is either higher or lower in value and further testing should be done.

Complete Blood Count

A CBC may be ordered prior to a surgery or to evaluate an infection, heart disease, fatigue, fever, anemia or cancer.

The test will analyze the white blood cells (WBCs), red blood cells (RBC's) and platelets. All of which are produced in the bone marrow.

The white blood cells battle bacteria, viruses and other infectious agents and are measured in thousands per cubic millimeter of blood.

The normal range for a white blood cell count is 4.0 to 11.0

The white blood cell differential measures the relative percentage of five types of WBCs:

Neutrophils - these fight bacterial infection

Basophils and eosonophils - these play a role in allergic responses

Lymphocytes and monocytes - these develop in an immune response to many infections.

Ask your physician for your normal ranges.

An absolute neutrophil count or ANC uses a formula that involves mature neutrophils (polys) and young neutrophils (bands). A decreased ANC can indicate bone marrow failure whilst a high ANC can be seen with infections and some leukemias.

The normal range for an ANC is 38% to 78% of all WBCs.

An abnormal white blood count could indicate a slight infection, a disorder of the bone marrow or just an allergy.

Red blood cells remove carbon dioxide from and carry oxygen to the tissues and are measured in millions per cubic millimeter of blood.

The normal range for a man is 4.5 to 6 and for a woman it's 4.2 to 5.4.

The hemoglobin or HGB value is measured in grams per deciliter of blood. Hemoglobin is the protein that carries oxygen.

The normal range for a man is 13.5 to 17.5 and for a woman it is 12 to 16.

The hematocrit or HCT value is the percentage of your blood that consists of red blood cells. A decrease in HCT is an indicator of anemia and can result in not enough oxygen being delivered to the tissues.

Normal range for a man is 40% to 52% and for a woman 37%to 47%.

Any problems with the red blood cells could indicate anemia, bleeding, some cancers, bone marrow disease or a side effect from a drug such as chemotherapy.

Platelets form clots and stop bleeding. These are measured in thousands per cubic millimeter of blood.

The normal range is 150 to 400

If there is a problem with the platelets it could be an indication of leukemia, thrombocytopenia, rare congenital disorders or a drug side effect.

Interpreting Urinalysis

A urinalysis will normally be ordered if you complain of low back pain, frequent or painful urination or if you have dark or bloody urine.

Protein - Under usual circumstances the kidneys do not allow protein to leak into the urine. A high level of protein (above 10mg/100ml) may suggest an abnormality such as kidney disease in which case other kidney function tests such as creatinine should be ordered.

Glucose and ketones - High levels of these indicate diabetes and you should then have a blood glucose test and other diabetes screening such as hemoglobinA1C.

Nitrite - high levels of nitrites are an indicator of a urinary tract infection.

Leukocyte esterase - These are produced by white blood cells and when this enzyme is present in the urine it may mean that there is an infection present.

Casts - These are cellular deposits that are formed in the kidney. The presence of these in the urine and their specific type can suggest many problems including diabetes and kidney disease.

Crystals - if these are present in small numbers most crystals are not significant but those crystals of the amino acid leucine can indicate severe liver disease.

RBCs - high levels of red blood cells in the urine can indicate trauma to the urinary tract or kidney, urinary tract infections or cancer.

How can you prevent errors?

At this point I would like to point out that the automated instruments that analyze blood are precise and most complete blood counts are accurate. The same applies to urinalysis but errors can occur.

So, be sure that your physician or hospital uses an accredited lab. If a lab is accredited by organizations such as the College of American pathologists then they will have a yearly inspection. Ask your doctor or hospital administrator if the lab they are using is accredited.

Do not assume that your tube has been labeled correctly. Mix-ups can and do happen. Ask the lab technician how they labeled the tube or better still ask to see it to make sure that it has your name on it.

Check your tube for clots. If it takes longer than two minutes to fill the tube your blood will likely start to clot rendering the sample useless for a CBC. Just ask the technician if there are any clots in the tube or better still ask to see the tube and tilt it gently. Should there be a large clot you will see it.