Laboratory Processes & Values
Partial List of “Laboratory Processes & Values”
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Pressed for time? Just fill out the quick inquiry form at the right, and one of our enrollment coordinators will contact you directly. Cerebrospinal fluid is a clear, colorless fluid that fills spaces within and around the central nervous system. It occupies the lateral ventricles, third ventricle, aqueduct, fourth ventricle, and the slender canal of the spinal cord, bathing the exterior of the brain and cord, occupying the areas within the bony confines. The internal and external circulations communicate through three small foramina (plural of foramen) in the wall of the fourth ventricle. If these become obstructed, hydrocephalus results – hydro=water and cephal- = head.
About 500 ml is formed in a day, with the total volume in the CNS (central nervous system) being 150 ml, there must be a rapid turnover. Absorption occurs through the arachnoid villi (air-rack-noyd vill-eye) into the venous sinuses.
Specimens for study of this fluid are obtained by lumbar puncture (LP), or, when necessary, by cisternal puncture.
Urinalyses are performed for detection of unusual color or odor, determining specific gravity, always expressed as 1.032 (note decimal placement), chemical screening, checking for bacteria, and examining the sediment microscopically. The typical test includes pH, protein or albumin, glucose or reducing substances, ketone bodies, occult blood, bilirubin, urobilinogen, and nitrate.
A gram stain smear may be obtained from urine to check for bacteria. Sometimes urine samples are centrifuged (spun) to look for cells, casts, and crystals. The sediment is observed on a microscopic slide (stained or unstained). The cells encountered are erythrocytes, leukocytes (not leucocytes), and renal tubular epithelial, transitional epithelial, or squamous epithelial cells. Casts and crystals are counted in a low-power or high-power microscopic field. Hyaline casts, red blood cells, tubular epithelial cells, granular, fatty, and waxy casts signify renal disease. Crystals found may include urate, oxalate, cystine, tyrosine, and crystals of certain drugs. This is the one used for employment or screening drug testing.
Specimens are obtained at various times, depending on what the doctor may be looking for. Random samples, first morning (most concentrated), clean-catch, postprandial (after eating) and an afternoon specimen. For different assays (quantitative) 24-hour specimens are obtained. The specimens may be obtained by catheter too.
Common urinary bacteria are caused by these pathogens: Escherichia coli (E.coli), (essur-eechia or doctors will say E. coli), Klebsiella, (kleb-see-ella), Proteus, Enterobacter, and Pseudomonas (sue-do-moan-us). These colonies are cultured (grown) and counted by microscpic means (high-power field or hpf).
Bacterium are organisms which working on the body in both complementary and destructive ways. The plural of the word is “bacteria.” You will hear mostly about two types relative to the way they use oxygen, “aerobic” and “anaerobic” (with and without oxygen). When samples are collected, you will hear about acid-fast types distinguished by their resistance to dye colorization, “gram-positive” and “negative,” and their “rod” shapes. Cultures (growing the bacteria colonies in Petri dishes in the lab) are done after swabbing the area, or collecting in other ways from infection site(s).
You will find a family of bacteria listed alphabetically in most dictionaries, and also a listing of all bacteria. The most commonly heard are listed below (they are traditionally capitalized). The plural form, (not often heard or typed) ends with –aceae. For instance, Enterobacter would be spelled Enterobacteriaceae, (en-tir-oh-back-ter-eesh-ee-uh) but you will type it as “Enterobacter.” Examples of such spellings are below with an “*” so you will be familiar with the concept (but hardly ever use it).
Peusodomonas (sue-doe-moan-us)
Campylobacter (cam-pill-oh-back-ter)
Legionella
Enterobacter (*enterobacteriaceae)
Escherichia (often heard with coli and abbreviated as E. coli) (ess-sir-eech-ee-uh)
Salmonella
Shigella
Klebsiella
Serratia (sir-ash-ee-uh)
Proteus
Hemophilus (heem-off-ill-us)
Actinobacillus (ack-tin-oh-back-sill-us)
Streptobacillus
Bacteriodes (*bacteriodaceae)(back-tir-ee-oyd-ees)
Leptotrichia (lep-toe-trike-ee-uh)
Neisseria (*neisseriaceae) (nye-seer-ee-uh)
Micrococcus (*micrococcaceae – micro-cock-say-she-uh)
Staphylococcus
Streptococcus
Bacillus
Clostridium (claw-strid-ee-um)
Lactobacillus
Listeria
Actinomyces (ack-tin-oh-mice-ees)
Mycobacterium
Streptomyces
Rickettsiia (rick-ett-see-uh)
Coxiella (cock-see-ella)
Chlamydia (kluh-mid-ee-uh)
Mycoplasma
BLOOD COUNT
Component Range
Red cell count 3.8 to 5.8 million (to the third power)
White cell count 4,500-11,000 million (to the third power)
Platelet count 150,000-450,000 mm (to the third power)
Hemoglobin Female: 34.9-46.9, Male: 39.8-52.0 ml
Red cell indices
Mean corpuscular hemoglobin
Concentration
Mean corpuscular volume
26.4-34.0 pg
31.5-35.8%
80.5-100.0 µm (to the third power)
MORE LAB – BLOOD COUNTS
Blood Cells
Red blood cells, also called erythrocytes, contain hemoglobin that gives red blood cells their color and carries oxygen from the lungs to the cells. If the number of erythrocytes is low, a patient may feel tired or short of breath.
The platelets or thrombocytes are tiny particles that help the blood to clot or stop bleeding when there is an injury. If the platelets are low, a patient may bleed or bruise easily.
The white blood cells, or leukocytes, are an important part of the body’s immune system. There are several types of white blood cells that help to prevent and fight infections.
The Complete Blood Count (CBC)
A complete blood count, or CBC, is a blood test done to determine if the bone marrow is working normally. A CBC describes the number, type and form of each blood cell. The count itself is usually done by a machine called a “Coulter counter” that performs several tests automatically on the blood sample. The CBC includes all of the following tests.
Three tests (the Red Blood Cell Count, Total Hemoglobin Concentration and Hematocrit) measure the amount of red blood cells. In general, they supply similar information. When low, these tests may indicate anemia or excess body fluid. When high, they may indicate polycythemia (an excessive number of red blood cells in the blood) or dehydration.
Red Blood Cell Count (RBC)
This test counts the number of red blood cells in a single drop (a microliter) of blood. “Normal” ranges vary according to age and sex. Normal values are:
# Men: 4.5 to 6.2 million
# Women: 4.2 to 5.4 million
Total Hemoglobin Concentration
This test measures the grams of hemoglobin in a deciliter (100 milliliters) of blood, which can help doctors determine the severity of anemia or polycythemia. Normal values are:
# Men: 13.2 to 17.7 g/dl
# Women: 11.9 to 15.5 g/dl
Any time that the hemoglobin level drops below 10 g/dl, a patient is considered to be anemic.
Hematocrit
Hematocrit measures the percentage of red blood cells in the sample. Normal values can vary – the normal ranges are:
# Men: 40% to 52%
# Women: 35% to 47%
Erythrocyte (RBC) Tests
Three tests measure the size of the red blood cells and the amount of hemoglobin contained in each cell.
# Mean Corpuscular Volume (MCV) measures the volume of red blood cells. Normal is 82 to 99 femtoliters.
# Mean Corpuscular Hemoglobin (MCH) measures the amount of hemoglobin in an average cell. Normal is 25 to 35 picograms.
# Mean Corpuscular Hemoglobin Concentration (MCHC) measures the concentration of hemoglobin in red blood cells. Normal is 32% to 36%.
White Blood Cell Count (WBC)
This test measures the number of white blood cells in a drop (microliter) of blood. Normal values range from 3,700 to 10,500, but can be altered greatly by factors such as exercise, stress, and disease. A low WBC may be due to chemotherapy, a viral infection, a toxic reaction, or another process in the bone marrow that is limiting production of normal WBCs. A high WBC count may indicate infection or leukemia. An increased risk of infection occurs once the WBC drops below 1,000 microliters.
WBC Differential
This test determines the percentage of each type of white blood cell in the sample. Multiplying the percentage by the total count of white blood cells indicates the actual number of each type of white blood cells in the sample. Normal values are:
Type Percentage Number
Neutrophil 50 – 60% 2,188 – 7,800
Eosinophils 1 – 4% 40 – 390
Basophils 0.5 – 2% 10 – 136
Lymphocytes 20 – 40% 875 – 3,300
Monocytes 2 – 9% 130 – 860
A serious infection can develop once the total neutrophil count drops below 500 microliters. Another word that is sometimes used for neutrophils is segmented neutrophils or “segs.”
Platelet Count
This test measures the number of platelets in a drop (microliter) of blood. Platelet counts increase during strenuous activity and in certain conditions called myeloproliferative disorders, infections, inflammation, cancers, and when the spleen has been removed. Platelet counts decrease just before menstruation. Normal values range from 150,000 to 400,000 per microliter. A count below 50,000 can result in spontaneous bleeding; below 5,000, patients are at risk of severe life-threatening bleeding.
What Do Abnormal Blood Counts Mean?
Red Blood Cells
Red blood cells carry oxygen to the tissues in your body. When your red blood cell count is low, your body tissues do not get enough oxygen to do their work. This results in a condition called anemia. In anemia, the hemoglobin and hematocrit are usually low.
Platelets
Platelets help your blood to clot, so that excessive bleeding is prevented when you hurt yourself. If there are not enough platelets in your blood, you may bleed or bruise more easily than usual.
The blood test that measures the platelets in your body is called a platelet count.
How to recognize low platelets
If there are not enough platelets in your blood, you may notice signs of bleeding such as:
# nosebleeds
# easy bruising
# prolonged bleeding from a cut
# black or bloody stools
# brown or red urine
# tiny pinpoint sized red or purple spots on your skin or on your gums
ENZYMES
An enzyme is a protein that acts as a catalyst. Enzyme assays are performed to determine how organs are functioning. They are used in clinical diagnostic efforts because the activity of some enzymes is markedly altered in the course of different disease processes. A related word is isoenzyme or isozyme (iso means equal, alike).
Here’s a list of enzymes analyzed for hepatitis, infectious mononucleosis, cirrhosis, myocardial (heart muscle) infarction, muscular dystrophy, etc. Try pronouncing them aloud. You will also find some listings in the laboratory section of the course.
Acid phosphatase (foss-fuh-taze)
Alanine aminotransferase (transfer-aze)
Alkaline phosphatase
Aspartate aminotransferase
Cholinesterase (coal-in-ester-aze)
Creatine kinase (kyne-aze)
Fructose bisphosphate aldolase
Glucosephosphate isomerase
Glutamyl transferase
Hydroxybutyrate dehydrogenase
Iditol dehydrogenase
Isocitrate dehydrogenase
Lactate dehydrogenase
Leucine aminopeptidase
Lipase
Nucleotidase
Ornithine carbamoyl transferase