Labs

Laboratory

TAPE 3B, Dictation 1

LABORATORY TESTS: THEIR FUNCTION AND IMPORTANCE

In the past decade there has been a dramatic increase in both the number of new diagnostic laboratory tests as well as in the complexity of the tests offered. This explosive growth in the field of laboratory medicine has been due to the demand by physicians for new and improved diagnostic procedures, combined with the ever-expanding capacity of modern technology to meet the demand with increasingly sophisticated laboratory methods and equipment.

On a daily basis medical transcriptionists come to contact with dictation which details the results of laboratory tests performed on patients. In order to accurately transcribe this material, it is important to be familiar with the names and abbreviations of many laboratory tests, the reasons they are offered, and the meaning of the results.

Laboratory tests can be performed in many different settings: clinics, physicians’ offices, health fairs, and sometimes even at home by the patient himself, but the greatest number of laboratory tests are performed within the hospital setting. Hospital laboratories are equipped with the most technologically advanced and automated equipment to handle hundreds of tests each day. The largest hospitals perform all standard laboratory tests, as well as many uncommon ones, which may be requested by smaller hospitals or clinics whose facilities are not equipped to handle unusual tests.

The laboratory of a hospital is divided into many smaller departments which perform specialized laboratory tests. This division of labor is also reflected to a great extent on the average laboratory slip which is used to report the results of laboratory tests. Various sections on the lap slip include hematology, blood bank, chemistry, coagulation, urinalysis, stool examination, microbiology, and cytology.

Hematology is concerned with the study of the formed components or cells of the blood. These cells include mature red blood cells, white blood cells, and platelets, as well as their immature forms. The function of the red blood cell is to carry oxygen from the lungs to the body tissues. The function of the white blood cell is to fight any foreign substances that enter the body, such as bacteria. Platelets function along with the coagulation factors in the blood to form a blood clot at the site of tissue injury. White blood cells are further differentiated into groups which have diagnostic value. These include lymphocytes, monocytes, neutrophils, eosinophils, basophils, and bands or immature neutrophils. In the jargon, lymphocytes are also called lymphs, monocytes are called monos, eosinophils are known as eos, and basophils as basos. Neutrophils have several different names, all derived from the fact that their cell nuclei are lobulated into segments. Neutrophils are known as segmented neutrophils or simply as segs. The more formal name for the neutrophil is the polymorphonucleated leukocyte. Polymorphonucleated means many-shaped nucleus, and leukocyte means white blood cell. This long term is frequently abbreviated as PMN or also as poly. So the terms neutrophil, seg, PMN, or poly all refer to the same type of white blood cell. In addition, the laboratory slip identifies many other abnormal blood cells which can be identified under the microscope. These are usually indicative of disease conditions. Unusual red blood cells include sickle cells, target cells, anisocytes, and poikilocytes. Unusual white blood cells include myelocytes and myeloblasts, which are noted in leukemia. A complete count, abbreviated CBC, includes tests which measures red blood cell and white blood cell levels. A CBC with differential also measures the levels of all of the different types of white blood cells as mentioned above. Other common tests are the hemoglobin and hematocrit, often dictated as H&H, which are indicative of the oxygen-carrying capacity of the blood as well as the percentage of red blood cells per blood sample. Normally, the hematocrit is about three times greater than the hemoglobin level for the same patient, so that if the patient=s hemoglobin level was reported as 15, you could expect that the hematocrit would be approximately 45.

The blood bank tests blood samples to determine a patient=s blood group and Rh type. Classification of blood groups is determined by the presence or absence of markers known as antigens on the surface of a person=s red blood cells. These are genetically determined so that a person=s blood group never changes. The most important classification is the ABO blood group system, which was discovered in the 1920s. An individual=s blood group is reported as type A, type B, type AB, or type O. Another important classification is that of the Rh group, which was discovered in 1940. When an Rh antigen is present on the surface of the patient=s red blood cells, that person is said to be Rh positive. A patient without this antigen is called Rh negative. The blood bank identifies each patient=s blood type and, if the physician orders it, matches it to compatible blood stored in the blood bank in case blood is needed for transfusion. The entire procedure is known as typing and crossmatching.

The chemistry section of the laboratory performs tests on many different electrolytes, fats, and other substances found in the serum, or clear fluid which separates from a clotted blood sample. Blood chemistries include tests for the electrolytes: sodium, potassium, calcium, and chloride. Fats include cholesterol, triglycerides, and low-density lipoproteins called LDL. Other substances tested include bilirubin, SGOT, SGPT, and LDH, which are used to evaluate liver function. Blood urea nitrogen, abbreviated BUN, and creatinine are useful indicators of kidney function. Uric acid levels are tested to diagnose the medical condition of gout. Often the physician orders a combination of tests under one name. For example, by checking a box next to the entry Aserum lipid profile@ on the laboratory slip, the physician can order the tests for cholesterol, triglycerides, total lipids, and lipoproteins. An elevated serum acid phosphatase is useful in detecting prostatic cancer. Blood glucose is frequently measured, particularly in diabetic patients. In the hospital this may be done with automated equipment, or it may be tested directly by the physician, nurse, or even by the patient by using a Dextrostix, a plastic stick with a chemically treated paper tip which changes color to correspond to various blood glucose levels. Only a drop of blood from a fingerstick is necessary to perform this test.

Laboratory tests which measure coagulation determine how quickly a patient=s blood clots when compared to normal values. The two common coagulation tests are the prothrombin time, abbreviated PT, and the partial thromboplastin time, abbreviated PTT.

Blood tests can also be done to verify pregnancy, detect the presence of mononucleosis, syphilis, or hepatitis, and to determine the status of the thyroid gland and hormones produced in other organs.

Urinalysis is performed to measure levels of glucose, ketones, protein, or blood, and to microscopically identify white blood cells, red blood cells, and casts in the urine. Ketones are the by-products of incomplete fat metabolism which occurs in diabetes when insulin levels are insufficient to metabolize glucose. When present in the urine, they indicate that a patient=s diabetes is not under control. Protein in the urine, also known as proteinuria, indicates damage to the nephron as a result of chronic inflammation or scarring or acute injury. Blood in the urine, also called hematuria, is a result of infection, trauma, or cancer. White blood cells in the urine, particularly neutrophils, are indicative of an acute infection in the bladder or kidneys. The concentration of the urine compared to distilled water is expressed as a numerical value referred to as specific gravity. Overall kidney function can be assessed by collecting a 24-hour urine specimen and measuring levels of creatinine. Urine can also contain mineralized material in the form of crystals. Crystals are most often formed from calcium and can grow into kidney stones, also known as renal calculi, which may lodge in the kidney or the ureter, causing extreme pain and obstruction of urine flow.

Stool samples are examined for occult or hidden blood as well as for parasitic worms or their eggs, ameba, bacteria, and fat content.

The microbiology department of the laboratory identifies infectious organisms through the use of microscopes and culture and sensitivity testing. Specimens for testing are obtained from urine, stool, blood, sputum, wound drainage, or other body fluids. A sample of the specimen is smeared onto a culture medium and incubated at 37EC for sufficient time to allow bacterial growth to occur. Antibiotic discs placed on the media of the culture plates permit evaluation of the sensitivity of the bacteria cultured to specific antibiotics. Antibiotic discs to which bacteria are sensitive are surrounded by a ring or zone of inhibition of bacterial growth. Bacteria that are resistant to an antibiotic will show no inhibition of growth around the disc. A rapid method to tentatively identify a pathogenic bacterium is a smear a sample on a slide and then stain the slide with the Gram=s stain. The stain differentiates between organisms that are gram-positive and gram-negative. The shape of the bacterium can provide further clues to the identity of the organism. The acid-fast stain is a specialized stain which is used to specifically identify Mycobacteria.

Cytology is the study of cells. Cells obtained from sputum samples, smears of the cervix, samples of cerebrospinal fluid, and from tissue biopsies are examined under a microscope for evidence of various abnormalities, but most specifically for signs suggestive of cancer. Cells may be obtained by aspirating a lesion or by washing or brushing or scraping the mucous membranes of a structure, such as the cervix or the bronchus.

Physicians order laboratory tests to be performed on patients for several different reasons which we will discuss below.

1. Laboratory tests are performed to diagnose disease in a patient who is ill. Along with the history and physical examination, laboratory tests form the basis for a sound medical diagnosis. In a patient with a sore throat, a throat culture would be ordered to determine whether or not the patient had a bacterial infection of the throat, and, if such an infection were present, to determine which antibiotics would be effective in treatment.

2. Laboratory tests are performed on apparently healthy patients to screen for hidden diseases. Well-known examples include use of the Papanicolaou smear to identify cervical cancer, and the self-administered test for occult or hidden blood in the stool as an indicator of colon cancer.

3. Laboratory tests are used to assess the extent of damage from disease processes. When a patient is suspected of having a heart attack, also called myocardial infarction, the physician will order a special test which measures the levels of specific substances which are released from damaged heart cells. These substances are collectively known as cardiac isoenzymes, which include lactic dehydrogenase and creatine phosphokinase, also called CPK.

4. Laboratory tests are used to monitor the effectiveness of treatment prescribed by the physician. For the diabetic patient receiving injections of insulin, glucose levels are monitored to insure that a normal balance is maintained between insulin levels and blood sugar, or glucose, in the blood.

5. Laboratory tests are used to monitor blood levels of certain medications. With some drugs it is of vital importance to know that the level of the drug in the bloodstream is within a therapeutic range. For example, a patient taking Dilantin may experience an epileptic seizure if the level of the drug falls below the therapeutic range. On the other hand, a patient in congestive heart failure being treated with digoxin can easily develop blood levels of the drug that are above the therapeutic range and, as a result, develop severe symptoms of toxicity. Periodic monitoring of blood samples can insure the drug levels in the blood remain within the therapeutic range.

6. Laboratory tests can be used to monitor the course of a disease. The flare-ups and remissions of rheumatoid arthritis can be followed by monitoring the rise and fall of the erythrocyte sedimentation rate, abbreviated as ESR. The erythrocyte sedimentation rate measures the time required for erythrocytes, or red blood cells, to settle to the bottom of a test tube of standard diameter.

Laboratory test results are measured and reported most often using the metric system. Common units of measure include centimeters, millmeters, cubic centimeters, milliliters, grams, milligrams, micrograms, milliequivalents, and percentages.

Laboratory test values are reported as numerical values. If the value falls within the range observed in normal individuals, it is considered normal. If it falls outside of this range, it is considered abnormal. The age and sex of a patient cause variation in the normal range of laboratory values. The accepted normal range for a particular laboratory test varies from one laboratory to another due to differences in equipment and methodology used in testing. Therefore, laboratory slips usually give the accepted normal range for that particular laboratory facility. The normal value is printed next to the blank space for the reported value for the individual patient. When transcribing, it is not unusual for the medical transcriptionist to hear the physician say, ANormal for our laboratory is . . . ,@ after dictating a patient=s test results.

The transcription of laboratory test terminology presents certain challenges. There are many facets with which the medical transcriptionist must become familiar. Correctly transcribing the name of a laboratory test or its abbreviation is just the first step. Numerical results must be transcribed with absolute accuracy. Care must be taken to accurately place decimal points and to correctly transcribe units of measure. It is also necessary to understand why a test was ordered and what the results indicate. Some dictations contain considerable detail concerning the test process, the use of special stains or dyes, as well as the significance of the results. As a student, you will want to diligently study this critical area of medical transcription. As a practicing medical transcriptionist, you will always be increasing your knowledge of laboratory tests and procedures as the technology of medicine increases daily.

The following dictations are brief examples of dictated laboratory tests results as found in the medical record.

The following are four original dictations of excerpts from laboratory procedures.

Dictation #1: LABORATORY DATA: The laboratory data revealed the sugar to be 179, but IVs were going. Cholesterol was 370 and triglycerides 589. Her HDL was only 33, and her LDL was 174. Her LDL/HDL ratio was 5.3. Her thyroid parameters were normal. Her hemoglobin was 12.6 and her white count 7,200.

Dictation #2: LABORATORY FINDINGS: Chemistry panel revealed an elevated BUN of 24.7, her cholesterol was 240, her SGOT was 49. Urine culture revealed no growth; however, urinalysis showed 6 to 10 white cells and 8 to 12 red cells per high-power field. There was 2+ bacteriuria noted. CBC showed a white count of 7,500, a hemoglobin of 12.4 g, and a normal differential.

Dictation #3: SIGNIFICANT LABORATORY DATA: Electrolytes on admission were normal, with a slightly elevated sodium at 148. BUN 125, creatinine 3.8, with the BUN and creatinine falling to 82 and 2.8, respectively. CBC on admission showed a white count of 12,500, hemoglobin 16.9, and hematocrit 51.0 due to hemoconcentration, all of those falling with simple rehydration to a white count of 7.9, hemoglobin, 12.9, and hematocrit 37.7. Skin scrapings of a rash which developed showed typical mites and multiple ova of Acarus scabiei.

Dictation #4: LABORATORY DATA: Electrolytes: Sodium is 133, potassium 4.8, chloride 100. CO2 is 31. Prothrombin time was 11.9. PTT was 27 seconds. Urine was clear. CBC showed a white count of 8.3 thousand with no shift. Hemoglobin and hematocrit were 14 and 40, respectively.

James L. Bennington, M.D.

Editor, Saunders Dictionary & Encylopedia of Laboratory Medicine and Technology

(W. B. Saunders Co., Philadelphia)

Chariman, Department of Pathology and Clinical Laboratories

Children=s Hospital, San Francisco, Ca.

FOOTNOTE:

Line 34. Cell nucleus is was changed to cell nuclei are for proper plural agreement.

Lines 36-38. Words under discussion may be either italicized or enclosed in quotation marks.

Line 3. Although a physician may dictate the slang term H&H, the transcriptionist should translate it when it appears in a medical report.

Line 32. Alternative: finger stick.

Line 14. Alternative: amoeba.

Lines 20-23. Alternative: disk, disks.

Line 25. The terms gram-negative and gram-positive are permanently hyphenated compound adjectives. Although it is traditional to eliminiate the hyphen in a compound adjective when it occurs after the noun, entries that appear as permanently hyphenated compound adjectives should retain their hyphens, no matter where they appear in a sentence.

Line 12. Creatinine was changed to creatine to correct the dictation error.

Lines 37-38. Causes was changed to cause for plural agreement (age and sex . . . cause).

Line 20. The heading Laboratory Data was added.

Line 20. Alternative: I.V=s.

Line 22. The hemoglobin value of twelve six is written 12.6.

Line 26. Alternative: 8-12 red cells/hpf.

Line 32. Alternative: 7,900.

Line 34. Acarus scabiei (italics or underscore).

Line 1. The heading Laboratory Data was added.

Lines 2-3. The white count value eight point three thousand can be written 8.3 or 8,300.

Line 3. Translate the slang H&H as hemoglobin and hematocrit, and change the singular verb was to were for plural agreement.

HEMATOLOGY - Red Blood Cells

RBC (Male)

4.2 - 5.6 M/µL

RBC (Female)

3.8 - 5.1 M/µL

RBC (Child)

3.5 - 5.0 M/µL

HEMATOLOGY - White Blood Cells

WBC (Male)

3.8 - 11.0 K / mm3

WBC (Female)

3.8 - 11.0 K / mm3

WBC (Child)

5.0 - 10.0 K / mm3

HEMOGLOBIN

Hgb (Male)

14 - 18 g/dL

Hgb (Female)

11 - 16 g/dL

Hgb (Child)

10 - 14 g/dL

Hgb (Newborn)

15 - 25 g/dL

HEMATOCRIT

Hct (Male)

39 - 54%

Hct (Female)

34 - 47%

Hct (Child)

30 - 42%

MCV

78 - 98 fL

MCH

27 - 35 pg

MCHC

31 - 37%

neutrophils

50 - 81%

bands

1 - 5%

lymphocytes

14 - 44%

monocytes

2 - 6%

eosinophils

1 - 5%

basophils

0 - 1%

CARDIAC MARKERS

troponin I

0 - 0.1 ng/ml (onset: 4-6 hrs, peak:

12-24 hrs, return to normal: 4-7 days)

troponin T

0 - 0.2 ng/ml (onset: 3-4 hrs, peak:

10-24 hrs, return to normal: 10-14 days)

myoglobin (Male)

10 - 95 ng/ml (onset: 1-3 hrs, peak:

6-10 hrs, return to normal: 12-24 hrs)

myoglobin (Female)

10 - 65 ng/ml (onset: 1-3 hrs, peak:

6-10 hrs, return to normal: 12-24 hrs)

GENERAL CHEMISTRY

acetone

0.3 - 2.0 mg%

albumin

3.5 - 5.0 gm/dL

alkaline phosphatase

32 - 110 U/L

anion gap

5 - 16 mEq/L

ammonia

11 - 35 µmol/L

amylase

50 - 150 U/dL

AST,SGOT (Male)

7 - 21 U/L

AST,SGOT (Female)

6 - 18 U/L

bilirubin, direct

0.0 - 0.4 mg/dL

bilirubin, indirect

total minus direct

bilirubin, total

0.2 - 1.4 mg/dL

BUN

6 - 23 mg/dL

calcium (total)

8 - 11 mg/dL

carbon dioxide

21 - 34 mEq/L

carbon monoxide

symptoms at greater than or equal to 10% saturation

chloride

96 - 112 mEq/L

creatine (Male)

0.2 - 0.6 mg/dL

creatine (Female)

0.6 - 1.0 mg/dL

creatinine

0.6 - 1.5 mg/dL

ethanol

0 mg%; Coma:

greater than or equal to 400 - 500 mg%

folic acid

2.0 - 21 ng/mL

glucose

65 - 99 mg/dL

(diuresis greater than or equal to 180 mg/dL)

HDL (Male)

25 - 65 mg/dL

HDL (Female)

38 - 94 mg/dL

iron

52 - 169 µg/dL

iron binding capacity

246 - 455 µg/dL

lactic acid

0.4 - 2.3 mEq/L

lactate

0.3 - 2.3 mEq/L

lipase

10 - 140 U/L

magnesium

1.5 - 2.5 mg/dL

osmolarity

276 - 295 mOsm/kg

parathyroid hormone

12 - 68 pg/mL

phosphorus

2.2 - 4.8 mg/dL

potassium

3.5 - 5.5 mEq/L

SGPT

8 - 32 U/L

sodium

135 - 148 mEq/L

T3

0.8 - 1.1 µg/dL

thyroglobulin

less than 55 ng/mL

thyroxine (T4) (total)

5 - 13 µg/dL

total protein

5 - 9 gm/dL

TSH

Less than 9 µU/mL

urea nitrogen

8 - 25 mg/dL

uric acid (Male)

3.5 - 7.7 mg/dL

uric acid (Female)

2.5 - 6.6 mg/dL

LIPID PANEL (Adult)

cholesterol (total)

Less than 200 mg/dL desirable

cholesterol (HDL)

30 - 75 mg/dL

cholesterol (LDL)

Less than 130 mg/dL desirable

triglycerides (Male)

Greater than 40 - 170 mg/dL

triglycerides (Female)

Greater than 35 - 135 mg/dL

URINE

color

Straw

specific gravity

1.003 - 1.040

pH

4.6 - 8.0

Na

10 - 40 mEq/L

K

Less than 8 mEq/L

C1

Less than 8 mEq/L

protein

1 - 15 mg/dL

osmolality

80 - 1300 mOsm/L

24 HOUR URINE

amylase

250 - 1100 IU / 24 hr

calcium

100 - 250 mg / 24 hr

chloride

110 - 250 mEq / 24 hr

creatinine

1 - 2 g / 24 hr

creatine clearance (Male)

100 - 140 mL / min

creatine clearance (Male)

16 - 26 mg / kg / 24 hr

creatine clearance (Female)

80 - 130 mL / min

creatine clearance (Female)

10 - 20 mg / kg / 24 hr

magnesium

6 - 9 mEq / 24 hr

osmolality

450 - 900 mOsm / kg

phosphorus

0.9 - 1.3 g / 24 hr

potassium

35 - 85 mEq / 24 hr

protein

0 - 150 mg / 24 hr

sodium

30 - 280 mEq / 24 hr

urea nitrogen

10 - 22 gm / 24 hr

uric acid

240 - 755 mg / 24 hr

COAGULATION

ACT

90 - 130 seconds

APTT

21 - 35 seconds

platelets

140,000 - 450,000 /ml

plasminogen

62 - 130%

PT

10 - 14 seconds

PTT

32 - 45 seconds

FSP

Less than 10 µg/dL

fibrinogen

160 - 450 mg/dL

bleeding time

3 - 7 minutes

thrombin time

11 - 15 seconds

CEREBRAL SPINAL FLUID

appearance

clear

glucose

40 - 85 mg/dL

osmolality

290 - 298 mOsm/L

pressure

70 - 180 mm/H2O

protein

15 - 45 mg/dL

total cell count

0 - 5 cells

WBCs

0 - 6 / µL

HEMODYNAMIC PARAMETERS

cardiac index

2.5 - 4.2 L / min / m2

cardiac output

4 - 8 LPM

left ventricular stroke work index

40 - 70 g / m2 / beat

right ventricular stroke work index

7 - 12 g / m2 / beat

mean arterial pressure

70 - 105 mm Hg

pulmonary vascular resistance

155 - 255 dynes / sec / cm to the negative 5

pulmonary vascular resistance index

255 - 285 dynes / sec / cm to the negative 5

stroke volume

60 - 100 mL / beat

stroke volume index

40 - 85 mL / m2 / beat

systemic vascular resistance

900 - 1600 dynes / sec / cm to the negative 5

systemic vascular resistance index

1970 - 2390 dynes / sec / cm to the negative 5

systolic arterial pressure

90 - 140 mm Hg

diastolic arterial pressure

60 - 90 mm Hg

central venous pressure

2 - 6 mm Hg; 2.5 - 12 cm H2O

ejection fraction

60 - 75%

left arterial pressure

4 - 12 mm Hg

right atrial pressure

4 - 6 mm Hg

pulmonary artery systolic

15 - 30 mm Hg

pulmonary artery diastolic

5 - 15 mm Hg

pulmonary artery pressure

10 - 20 mm Hg

pulmonary artery wedge pressure

4 - 12 mm Hg

pulmonary artery end diastolic pressure

8 - 10 mm Hg

right ventricular end diastolic pressure

0 - 8 mm Hg

NEUROLOGICAL VALUES

cerebral perfusion pressure

70 - 90 mm Hg

intracranial pressure

5 - 15 mm Hg or 5 - 10 cm H2O

ARTERIAL VALUES

pH

7.35 - 7.45

PaCO2

35 - 45 mm Hg

HCO3

22 - 26 mEq/L

O2 saturation

96 - 100%

PaO2

85 - 100 mm Hg

BE

-2 to +2 mmol/L

VENOUS VALUES

pH

7.31 - 7.41

PaCO2

41 - 51 mm Hg

HCO3

22 - 29 mEq/L

O2 saturation

60 - 85%

PaO2

30 - 40 mm Hg

BE

0 to +4 mmol/L