What is a Complete Blood Count (CBC)?

What are LDL, HDL, and Triglycerides?

What is a Comprehensive Metabolic Panel?

What is a Hemoglobin A1C assay? (or how do we screen for diabetes?)

What about my Vitamin-D Level?

What do These Hepatitis Tests Mean?

Herpes Blood Testing

Why Don’t you Check my Blood Type?

 

What is a Complete Blood Count (CBC)?

The CBC is used as a broad screening test to check for such disorders as anemia, infection, and many other diseases. It is actually a panel of tests that examines different parts of the blood and includes the following:
• White blood cell (WBC) count is a count of the actual number of white blood cells per volume of blood. Both increases and decreases can be significant.
• White blood cell differential looks at the types of white blood cells present. There are five different types of white blood cells, each with its own function in protecting us from infection. The differential classifies a person’s white blood cells into each type: neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
• Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood. Both increases and decreases can point to abnormal conditions.
• Hemoglobin measures the amount of oxygen-carrying protein in the blood.
• Hematocrit measures the percentage of red blood cells in a given volume of whole blood.
• The platelet count is the number of platelets in a given volume of blood. Both increases and decreases can point to abnormal conditions of excess bleeding or clotting. Mean platelet volume (MPV) is a machine-calculated measurement of the average size of your platelets. New platelets are larger, and an increased MPV occurs when increased numbers of platelets are being produced. MPV gives your doctor information about platelet production in your bone marrow.
• Mean corpuscular volume (MCV) is a measurement of the average size of your RBCs. The MCV is elevated when your RBCs are larger than normal (macrocytic), for example in anemia caused by vitamin B-12 deficiency. When the MCV is decreased, your RBCs are smaller than normal (microcytic) as is seen in iron deficiency anemia or thalassemias.
• Mean corpuscular hemoglobin (MCH) is a calculation of the average amount of oxygen-carrying hemoglobin inside a red blood cell. Macrocytic RBCs are large so tend to have a higher MCH, while microcytic red cells would have a lower value.
• Mean corpuscular hemoglobin concentration (MCHC) is a calculation of the average concentration of hemoglobin inside a red cell. Decreased MCHC values (hypochromia) are seen in conditions where the hemoglobin is abnormally diluted inside the red cells, such as in iron deficiency anemia and in thalassemia. Increased MCHC values (hyperchromia) are seen in conditions where the hemoglobin is abnormally concentrated inside the red cells, such as in burn patients and hereditary spherocytosis, a relatively rare congenital disorder.
• Red cell distribution width (RDW) is a calculation of the variation in the size of your RBCs. In some anemias, such as pernicious anemia, the amount of variation (anisocytosis) in RBC size (along with variation in shape – poikilocytosis) causes an increase in the RDW.

 

What are LDL, HDL, and Triglycerides?

 

LDL cholesterol

LDL cholesterol can build up on the walls of your arteries and increase your chances of getting heart disease.
That is why LDL cholesterol is referred to as “bad” cholesterol. The lower your LDL cholesterol number, the
better it is for your health. The table below explains what the numbers mean.

LDL Cholesterol LDL

Cholesterol Category

Less than 100 Optimal
100 – 129 Near optimal/above optimal
130 – 159 Borderline high
160 – 189 High
190 and above Very high

If you have heart disease or blood vessel disease, some experts recommend that you should try to get your LDL cholesterol below 70. For people with diabetes or other multiple risk factors for heart disease, the treatment goal is to reach an LDL of less than 100.

 

HDL Cholesterol

When it comes to HDL cholesterol — “good” cholesterol – the higher the number, the better it is for your health.
This is because HDL cholesterol protects against heart disease by taking the “bad” cholesterol out of your blood and keeping it from building up in your arteries. The table below explains what the numbers mean.

HDL Cholesterol

HDL-Cholesterol Category

60 and above High; Optimal; helps to lower risk of heart disease
Less than 40 in men and less than 50 in women Low; considered a risk factor for heart disease

 

Triglycerides

Triglycerides are the chemical form in which most fat exists in food and the body. A high triglyceride level has been linked to the occurrence of coronary artery disease in some people. Here’s the breakdown.

Triglycerides

Triglycerides Category

Less than 150 Normal
150-199 Borderline high
200-499 High
500 or higher Very high

 

What is a Comprehensive Metabolic Panel?

The Comprehensive Metabolic Panel (CMP) is a frequently ordered panel of tests that gives your doctor important information about the current status of your kidneys, liver, and electrolyte and acid/base balance as well as of your blood sugar and blood proteins. Abnormal results, and especially combinations of abnormal results, can indicate a problem that needs to be addressed.
The CMP includes:
Glucose
Calcium
Both increased and decreased levels can be significant.

 

Proteins

Albumin
Total Protein
Albumin, a small protein produced in the liver, is the major protein in serum. Total protein measures albumin as well as all other proteins in serum. A decrease in albumin can signify malnutrition or the loss of protein through unhealthy kidneys. The other major protein type in the serum is immunoglobulin or antibodies, these are the proteins your immune system uses to fight infections. Decreases can point to immune deficiency. Increases in immunoglobulins can be a sign of infection or malignancy.

 

Electrolytes

Sodium
Potassium
CO2 (carbon dioxide, bicarbonate)
Chloride
The concentrations of sodium and potassium are tightly regulated by the body as is the balance between the four molecules. Electrolyte (and acid-base) imbalances can be present with a wide variety of acute and chronic illnesses. Chloride and CO2 tests are rarely ordered by themselves.

 

Kidney Tests

BUN (blood urea nitrogen)
Creatinine
BUN and creatinine are waste products filtered out of the blood by the kidneys. Increased concentrations in the blood may indicate a temporary or chronic decrease in kidney function. When not ordered as part of the CMP, they are still usually ordered together.

 

Liver Tests

ALP (alkaline phosphatase)
ALT (alanine amino transferase, also called SGPT)
AST (aspartate amino transferase, also called SGOT)
Bilirubin
ALP, ALT, and AST are enzymes found in the liver and other tissues. Bilirubin is a waste product produced by the liver as it breaks down and recycles aged red blood cells. All can be found in elevated concentrations in the blood with liver disease or dysfunction. An isolated increase in bilirubin can be a sign of congenital production of abnormal red blood cells that are broken down more rapidly or autoimmune destruction of normal red blood cells.

 

What is a Hemoglobin A1C assay? (or how do we screen for diabetes?)

The A1C test is a common blood test used to diagnose type 1 and type 2 diabetes and then to gauge how well you’re managing your diabetes. The A1C test goes by many other names, including glycated hemoglobin, glycosylated hemoglobin, hemoglobin A1C and HbA1c.

The A1C test result reflects your average blood sugar level for the past two to three months. Specifically, the A1C test measures what percentage of your hemoglobin — a protein in red blood cells that carries oxygen — is coated with sugar (glycated). A very high A1C level is diagnostic for diabetes and a moderately elevated A1C is predictive of increased risk of developing diabetes.

 

What about my Vitamin-D Level?

Vitamin D deficiency is a controversial topic, and it seems that conflicting information emerges nearly daily. My thoughts about vitamin D are:
✦ True, symptomatic vitamin D deficiency is likely fairly uncommon.
✦ Vitamin D levels 20 ng/ml are probably sufficient.
✦ Giving supplements to people with a Vitamin D level around 20 probably causes more harm than good.
✦ In people who have a vitamin D level lower than 20, a 500 unit vitamin D-3 supplement taken daily is probably not a bad idea.

Institute of Medicine Report about Vitamin D and Calcium Supplementation
New York Times Article about the IOM Report

 

What do These Hepatitis Tests Mean?

As part of the evaluation of new patients, I typically perform antibody testing for hepatitis A and B. Most young adults have antibodies to both because of vaccination. Having antibodies against hepatitis does not mean that one has hepatitis.

 

Hepatitis Vaccination Recommendations

Hepatitis A is a virus that is spread by the fecal-oral route. Typically it is contracted by eating food prepared by hepatitis A infected individuals that have not practiced good handwashing techniques before preparing food, or drinking water that has been contaminated by sewerage. It can also be acquired through oral-anal sexual contact. While most hepatitis A cases occur outside of the United States, there are occasional outbreaks in the United States, typically originating from an infected food service worker. Acquiring hepatitis A in the United States is rare, but not unheard of. If one plans to travel to under-developed countries or engages in oral-anal sexual behaviors, getting vaccinated for hepatitis A is recommended. Those who don’t travel outside of the U.S. or travels only to more developed areas with good sanitation, are at low enough risk that hepatitis A vaccination is not as important, but certainly not unrealistic to do.

LINK TO CDC HEPATITIS A FACT SHEET
Hepatitis B is a blood-borne virus that is spread through exposure to the blood or body fluids of an infected individual – sexual contact, the sharing of contaminated needles, and from infected mother to child. In it’s mode of transmission it is much like HIV, but Hepatitis B is 100 times more infectious than HIV.

When one gets Hep B sometimes they have no symptoms, but sometimes they become extremely ill for several weeks. About 1-5 in 1000 patients with acute Hepatitis B infection will die. Most people with Hepatitis B recover with no lasting problems, but about 5% of adults infected with the virus will develop a chronic, lifelong infection that increases their risk of early death from cirrhosis, liver failure, and liver cancer.

 

Groups who should be vaccinated include:

•Sexually active individuals with multiple sex partners and men who have sex with men.
•Household contacts of patients with hepatitis B.
•Intravenous drug users.
•Healthcare workers.
•Patients on chronic hemodialysis (for kidney failure) and patients requiring repeated blood or blood product transfusion should also be vaccinated.
•Patients with chronic liver disease.
LINK TO CDC HEPATITIS B FACT SHEET

 

Herpes Blood Testing

I do not routinely order herpes blood tests. Many people have antibodies to herpes simplex one and/or two. Most of these people will never have an outbreak of herpes lesions. Testing for antibodies is not really useful, because asymptomatic people with antibodies to herpes probably don’t benefit from treatment, and there is little evidence that suggests that treating someone who has been exposed will make them less infectious to sexual partners. The United States Preventive Medicine Task Force advises against testing.

 

The USPSTF recommends against routine serological screening for HSV in asymptomatic adolescents and adults.
Rating: D Recommendation.

Rationale: The USPSTF found no evidence that screening asymptomatic adolescents and adults with serological tests for HSV antibody improves health outcomes or symptoms or reduces transmission of disease. There is good evidence that serological screening tests can accurately identify those persons who have been exposed to HSV. There is good evidence that antiviral therapy improves health outcomes in symptomatic persons (e.g., those with multiple recurrences); however, there is no evidence that the use of antiviral therapy improves health outcomes in those with asymptomatic infection. The potential harms of screening include false-positive test results, labeling, and anxiety, although there is limited evidence of any potential harms of either screening or treatment. The USPSTF determined the benefits of screening are minimal, at best, and the potential harms outweigh the potential benefits.
Click here for source of quotation.

 

Why Don’t you Check my Blood Type?

There are a few reasons why learning your blood type would be valuable:

1.If you need a blood transfusion
2.If you are pregnant
3.If you want to donate blood for someone with a specific blood type

There are several reasons why primary care doctors do not routinely check people’s blood type:

1.If you need a blood transfusion, the ER is not going to trust that you remember your blood type accurately, because getting improperly matched blood is nearly always fatal. They are going to not only verify your blood type but also they are going to check the blood that they are going to give you specifically against your blood, to see if you may have pre-formed antibodies against the many minor antigens on red blood cells. There are hundreds of other proteins on the surface of red blood cells beyond the ABO and Rh antigens.
2. If you are going to donate blood for a specific person, it really doesn’t matter what your blood type is. Your blood is unlikely going to be used for that person. Your donation of blood is valued and appreciated as a replenishment for the blood your loved one will get, but even when one is a blood type (ABO Rh) match, it doesn’t mean that your blood will be compatible.
3.In pregnancy, one’s blood type is routinely evaluated early in pre-natal care, previous results are really not looked at.