Blood Test Lingo and Abbreviations Quiz

Answer: Biochemistry

In the US, a Basic Metabolic Panel is a panel of seven or eight biochemistry tests used as a general screen. It is the most commonly ordered biochemistry test. The seven tests are glucose, four electrolytes (sodium, potassium, chloride, and carbon dioxide or bicarbonate), and two kidney markers (blood urea nitrogen and creatinine). In some labs, calcium is added. Sometimes in the US you will see these tests written "Chem7" or "Chem8".

In short, this panel is a screening panel for blood sugar, fluid balance, and kidney function. If calcium is tested, it is a mineral that is necessary for bone strength, proper blood clotting, and muscle, nerve, and heart function.

In the UK, Australia, and New Zealand, the term used is Urea and Electrolytes, but the tests are not just the five specified in the abbreviation, but the seven included on the American BMP, including glucose and creatinine. Calcium may be included.

In Canada, electrolytes, urea, and creatinine tend to be ordered as three distinct individual tests.

Answer: Biochemistry

Liver function tests (LFTs), as a group, include measurements of four enzymes, two proteins, and a waste product:

ALT (Alanine Aminotransferase) is an enzyme found almost exclusively in the liver that spills into the bloodstream when liver cells are damaged.

AST (Aspartate Aminotransferase) is similar to ALT, but the enzyme is found in the liver, heart, and muscles. It helps detect cell injury in these tissues.

ALP (Alkaline Phosphatase) is an enzyme found in the liver and bones that rises with bile duct blockages or bone issues.

GGT (Gamma-Glutamyl Transferase) is an enzyme that differentiates if high ALP levels are due to liver or bile duct disease rather than bone disease.

Lactate dehydrogenase (LDH) is sometimes added as a fifth enzyme tested. While it is found in the liver, it is also found in the heart, kidneys, muscles, and erythrocytes. It is a non-specific marker: It demonstrates tissue damage has occurred but not whereabouts in the body.

The two proteins measured by LFTs are albumin and 'total protein':

Over half the amount of total protein in the bloodstream is albumin. It has a long half-life of 20 days; therefore, low serum albumin signifies long-standing, chronic liver dysfunction. Total protein (TP) in the blood is the sum of albumin plus globulins (proteins that help with immunity and fight infection). Comparing albumin with globulins (TP minus albumin) differentiates between liver disease, renal disease, and immune system pathology.

Bilirubin is the waste product generated by the liver when it breaks down erythrocytes (red blood cells). High levels cause jaundice and signify either hepatic blockages or liver processing issues.

A complete metabolic panel (CMP) in the US is a BMP plus liver function tests. Because these biochemistry tests are ordered in very high numbers, high-throughput analysers have been developed to handle them. Often, it is easier and quicker to test for a CMP rather than a BMP +/- LFTs as ordered.

Answer: Haematology

A Complete Blood Count (CBC) and a Full Blood Count (FBC) are the same test. In Canada and the US, it is a CBC; in the UK, Ireland, Australia, and New Zealand, it is called a FBC. However, the parameters measured are the same.

This is a screening test for the cells in the bloodstream (the CMP is a screening test for the constituents in the serum (liquid) component of the blood). The three types of cells measured are erythrocytes (red blood cells that carry oxygen), leucocytes (white blood cells that fight infection), and platelets (which help clot your blood when you bleed). This is one of the two most requested lab tests, and huge high-throughput analysers have been designed and implemented to cope with the demand. The parameters they measure include:

1. Number of red blood cells (RCC). These are highly efficient cells shaped to carry the most oxygen molecules they can, from when they pick up oxygen from the alveoli in the lungs to when they deposit it in each cell so energy transfer can be facilitated. A low red cell count (RCC) is associated with anaemia (various causes), and a high RCC is associated with dehydration, low oxygen levels, bone marrow disease (erythrocytes are made in the bone marrow), or performance-enhancing drug ingestion.

2. Haemoglobin (Hb): This is the protein within erythrocytes that carries oxygen to the cells. A good analogy is the cargo each truck carries. You can have the correct number of RBCs, but can still be anaemic if each cell is not carrying enough haemoglobin.

3. Leucocytes (WBCs) are infection-fighting cells. They seek and destroy harmful bacteria and other harmful invaders. They increase in number in response to inflammation and are lowered in immunocompromised situations. There are five types of leucocytes, and a rise or fall in each type can indicate different types of inflammation and infection. Contemporary analysers enumerate these five types as part of the CBC/FBC, but if a doctor wants an independent differential count, they will add "+ diff" or "+ smear". The latter is a stained blood film of a patient's blood. This allows not only the count of each type of leucocyte but also a qualitative assessment of those cells.

4. Haematocrit measures the percentage of blood that comprises the red cells. A normal haematocrit is about 40% depending on sex, so the plasma, the liquid part of blood, is around 60%. A low haematocrit indicates anaemia.

5. There are four RBC parameters that collectively help classify anaemias when the RCC and Hb are low. These are Mean Corpuscular Volume (MCV); Mean Corpuscular Haemoglobin (MCH); Mean Corpuscular Haemoglobin Concentration (MCHC); and Red Cell Distribution Width
(RDW)

6. Platelets clot blood. They are tiny fragments of cells that clump together when someone bleeds through injury. A low platelet count (thrombocytopenia) means bruising or bleeding occurs more easily. A high count (thrombocytosis) can increase the risk of blood clotting without bleeding

7. Mean Platelet Volume (MPV) measures the average size of platelets. Young platelets are large, so a high MPV can mean a patient is producing new platelets quickly, whereas a low MPV indicates a bone marrow production issue.

Answer: Microbiology

An MCS or M/C/S, stands for microscopy, culture, and sensitivities. It is the basic test in microbiology, specifically for bacteria that cause disease.

While there are many types of microscopy in the microbiology lab, there are two main types: Unstained and Gram stain.

In the simplest method used for urine samples when a urinary tract infection is suspected, a sample of urine is placed on a slide and viewed with a special microscope called a phase contrast microscope. This allows red and white cells and bacteria to be visualised and counted, all of which are absent in normal urine. The second is called the Gram stain. Invented in 1884, it is still the mainstay of microscopy in bacteriology. It is simple and quick to perform and divides bacteria into four groups: Gram-positive (purple) and Gram-negative (pink/red) types, and cocci (round-shaped) from bacilli (rod-shaped). A "No organisms seen" report is also helpful. This initial information gives physicians a guide to the correct therapy at an early stage.

Culture is the plating out of the specimen on solid and liquid media to see what specific bacterium, if any, is causing an infection. Because some infection sites have their own 'normal' bacteria, selective and differential media are used to try to differentiate between normal bacteria and pathogenic bacteria from the specimen provided. A minimum of sixteen hours of incubation is needed to determine this status, and plates are kept for a minimum of 48 hours. Once a 'pathogen' has been identified, it can be identified by various methods. Identification is quick once pathogenic bacteria have grown on solid media. Identification can be automated.

Sensitivities are tests to determine which antibiotics will kill the identified pathogen(s). In its simplest form, the pathogen is added to normal saline, then smeared over an entire culture plate, with subsequent addition of small round paper discs impregnated with different antibiotics. If the pathogen is sensitive to any antibiotic, it will have a zone of inhibition around it where it will not grow. If the pathogen is resistant to that antibiotic, then the pathogen will grow right up to the disc. This method can be automated so results are available in a few hours.

Answer: Microbiology

Blood cultures are taken from patients with suspected septicaemia which is also known as blood poisoning. Blood is sterile, so if a patient is septic, they are very ill and immediate treatment is necessary.

To determine if a patient is septic, samples of their blood are collected and injected into bottles containing broth. This broth is very nutritious for most bacteria, and, if present, the bacteria will grow rapidly until they are visible. Until 1990, this was done manually, with bottles being examined daily. Automation was first used in the late 1980s. Bottles were placed in incubators that agitated the bottles to encourage growth. Additionally, the bottles have a pH indicator in their base. If bacteria are present, they blow off carbon dioxide and change the pH of the medium. This change in pH is detected by the instrument, and the bottle is flagged as positive, indicating an urgent workup. Bottles are usually kept for five days before being declared negative and being discarded by the instrument.

Positive bottles are then processed using M/C/S methodology as described in the previous question.

Answer: Haematology

Most large hospitals have a blood bank or an immunohaematology department, where blood for transfusion is prepared and stored. In smaller hospital labs, this service is provided by the haematology lab.

When people have severe bleeding from surgery ot trauma, they need blood quickly. In the emergency department, where trauma cases are first seen, that need may be so acute that they cannot wait for testing of compatible blood donations, so they are pumped with O negative blood (the universal donor), as any reaction to the blood transfusion is secondary to the acute loss of blood.

In the not-so-urgent cases where a patient is losing blood 'slowly' or an operation is scheduled where there will be a possible large loss of blood, a crossmatch (XM or Xmatch) is performed. In nearly all cases, the recipient and the donor blood will be the same group (eg A+, B Negative). In a crossmatch, the red cells of donated blood are mixed with serum (plasma minus clotting factors) from the patient to determine if there is clumping or destruction of cells, which indicates an adverse antibody reaction and that particular blood donation is not compatible. When the number of required units has been determined to be compatible, the compatible blood donations are reserved for that particular time. Unused units are checked back into the blood bank for use by another patient.

Answer: Haematology

A PT/INR measures how many seconds it takes for a patient's blood to clot (PT). It then standardises that result so that interpretation is unambiguous and not method-dependent.

Normal prothrombin time (PT) is 11-13.5 seconds. The International Normalized Ratio (INR) is a global formula that adjusts the PT score so results from different labs are comparable. The reference range for people not on blood thinners is 0.8 to 1.1.

These results inform us about several patient scenarios:

1. It checks to see if patients taking warfarin (a blood thinner) is effective and safe. The INR for these patients should be between 2.0 and 3.0.
2. A high PT/INR means the blood clots too slowly, which increases the risk of bleeding and indicates liver disease, low Vitamin K, or a too-high warfarin dose.
3. A low PT/INR means the blood clots too fast. This raises the risk of systemic blood clots without bleeding occurring. This happens with high vitamin K ingestion or a low blood thinner dose.

The PT/INR is usually ordered in conjunction with an aPTT (activated partial thromboplastin time). This test measures how long it takes blood to clot via the intrinsic pathway, whereas the PT measures the extrinsic pathway. The aPTT detects specific bleeding disorders not detected by the PT, such as Haemophilia A (Factor VIII deficiency) and Haemophilia B (Factor IX deficiency). In these cases, the PT is normal, but the aPTT is prolonged. The aPTT is also used to monitor heparin therapy (a blood thinner with a different course of action to warfarin).

Answer: Biochemistry

HbA1c (glycosylated hemoglobin) is a marker for diabetes mellitus and, as such, is measured in the biochemistry lab (Methods used detect the glucose molecules on the Hb, not measure the glycosylated Hb per se). In every person, a small amount of haemoglobin (Hb) is glycosylated. This means some of the haemoglobin has a glucose molecule attached to it. In diabetics who have increased glucose circulating in the blood, they have higher levels of glycosylated haemoglobin (HbA1C) than non-diabetics. As the lifespan of an erythrocyte is 120 days, the amount of HbA1c in a diabetic patient's blood is a measure of the control they had over their glucose levels over the last 3-4 months. Non-diabetics have HbA1c levels less than 6.5%. This is the target for diabetics.

Diabetes mellitus (DM) was traditionally diagnosed by a glucose tolerance test (GTT). This is when a patient is given a drink with 75g of glucose, and then their glucose levels are measured at one and two hours post-drink. In diabetic patients, the glucose levels remain high where non-diabetics have normal glucose levels after two hours.

However, over time, an HbA1c level over 6.5% became diagnostic of DM in Type II patients (Type I patients need additional tests). The GTT had become almost obsolete. (It is still useful to diagnose gestational diabetes.) Patients who have not been diagnosed as diabetic and have a high HbA1c have a repeat test to confirm a diagnosis of Type II DM.

Answer: Microbiology

Hepatitis B Virus Nucleic Acid Amplification Test (HBV NAAT) is commonly referred to as an HBV DNA test or HBV viral load test, which measures the actual genetic material of the virus in a patient's blood. In nearly all laboratory testing, the nucleic acid amplification test will be measured using the polymerase chain reaction (PCR). It can be qualitative ("Detected" or "Not Detected") or quantitative, where it gives an exact number of viral particles in a blood sample. This is used to monitor progression of an active disease.

It is not a screening test (except in blood and tissue donor screening). In blood banks and transplantation centers, where NAAT screening [for HBV, Hepatitis C, and HIV] is mandatory). NAAT is used concurrently with serological testing. These tests detect acute infections in the incubation period before antibodies or antigens become detectable.)

In general, serological testing is used for HBV testing. Most laboratories perform a triple panel. These three tests are:

HBsAg (Hepatitis B Surface Antigen), which detects an active or chronic infection by detecting a protein on the virus itself; Anti-HBs (Hepatitis B Surface Antibody), which determines if a person has immunity; and Total Anti-HBc (Hepatitis B Core Antibody), which identifies past exposure or current infection. Serological testing is not as sensitive as NAAT. In some cases, HBV NAAT is ordered when serological testing is inconclusive.

Answer: Haematology

A reticulocyte is an immature erythrocyte. When they are produced in the bone marrow, they lose their nucleus to maximise their haemoglobin-carrying capacity but briefly retain RNA remnants before becoming mature erythrocytes. A reticulocyte is an erythrocyte with some residual RNA. They typically are less than 2% of total erythrocytes in blood.

A reticulocyte count (Retic) that is higher or lower than normal usually indicates a blood disorder.

A low reticulocyte count is indicative of hypoproliferative anaemia. These types of anaemia happen when the bone marrow can't make enough erythrocytes. These include chronic disease, aplastic, and nutritional anaemias.

High reticulocyte counts occur when you lose mature erythrocytes faster than your bone marrow can produce them, resulting in reticulocytes being released into the bloodstream prematurely. This happens in haemolytic anaemias where red cells are destroyed before their normal 120-day lifespan. Blood loss, whether it is acute or chronic, has a similar effect.

Answer: Microbiology

A Respiratory Polymerase Chain Reaction (Resp PCR) panel is a rapid test that detects bacteria and viruses that cause common respiratory infections. From a single nose or throat swab, the test uses PCR technology to test for these pathogens simultaneously: COVID-19, Influenza A and B (flu), Respiratory Syncytial Virus (RSV), Adenovirus, Rhinovirus (common cold), and Parainfluenza (all viruses), and bacteria such as Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis (whooping cough). Note that these last three are bacteria that are very hard to grow or very slow to grow on solid media. The number of pathogens tested in a Resp PCR panel) can vary slightly between labs.

The panel can usually give results within an hour of receipt in the lab. There is usually concurrent testing on solid media (MCS) for common bacterial pathogens such as Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus.

Answer: Biochemistry

Thyroid function tests (TFTs) are frequently requested because thyroid hormones regulate the body's metabolism, and thyroid abnormalities can mimic many common conditions. Thyroid disorders can cause symptoms like fatigue, anxiety, weight changes, mood swings, and hair loss. These vague signs overlap with depression, stress, and aging. Because thyroid hormones are easily measured in a biochemistry lab, clinicians often order thyroid tests first to rule out thyroid disease.

When the thyroid gland malfunctions, it can produce less thyroid hormone (hypothyroidism) or too much (hyperthyroidism); this is common, especially in women and older adults. Patients with an underactive thyroid need replacement, which requires regular monitoring to optimise dosage. TFTs are used in routine hospital admissions or general medical evaluations as part of a broad panel to investigate fatigue, cardiovascular issues such as atrial fibrillation (irregular heart rate) or tachycardia (fast heart rate).

The thyroid gland makes two main hormones using iodine from dietary intake. Table salt has iodine added to ensure the general population consumes enough iodine. Thyroxine (T4) has four molecules of iodine and is a 'precursor' of Triiodothyronine (T3 - three molecules of iodine), which is the active form. T3 affects just about every cell in the body by controlling metabolic rate, heart rate, temperature, and growth and development. The brain regulates thyroid production with a feedback loop. This occurs in the pituitary gland in the brain, releasing thyroid-stimulating hormone (TSH) to make more or less T4 depending on the amount of T3 and T4 circulating in the blood. T4 and T3 are transported around the blood on a protein called thyroxine-binding globulin (TBG). Only a small fractions exists in 'free form' (FT4 and FT3). Some labs measure T4 and T3. Others measure FT3 and FT4.+

As such, measurement of TSH is the initial TFT to perform. If TSH is high, T4 and/or T3 are measured. If T4 is low, these two results indicate primary hypothyroidism. When TSH is low, T4 and T3 are measured. Low TSH with elevated T4 or T3 confirms hyperthyroidism. There are other, less common, combinations and additional tests, such as thyroid antibody tests, before a definitive diagnosis can be made.