1. Specialty Laboratory Tests
Chapter 44
Specialty Laboratory Tests

2. Pregnancy Tests When used
When pregnancy is suspected
To rule out pregnancy
Before prescribing birth control pills, x-ray studies, certain antibiotics, or other drugs
For females who are to undergo surgery
Based on detection of human chorionic gonadotropin (hCG)

3. Pregnancy Tests Commercial/home pregnancy tests Variety available
Easy to perform and interpret
Give rapid results
OTC products
Should be confirmed by laboratory test using appropriate controls

4. Pregnancy Tests Testing methods
Used in conjunction with physical examination
Positive reaction to test does not necessarily indicate normal pregnancy

5. Pregnancy Tests Testing methods Quality control
Kits must be stored and used at temperature directed by manufacturer
Built-in control
Expiration date

6. Pregnancy Tests Slide test or agglutination inhibition test
Based on inhibition of agglutination of hCG-coated latex beads
Antiserum added to urine on microscope slide
Negative agglutination indicates positive pregnancy
Positive agglutination of latex beads indicates negative pregnancy

7. Pregnancy Tests Enzyme immunoassay (EIA) test
Can be designed in various ways
Always involves an antigen, antibody specific for antigen, and second antibody
May be designed to detect particular antibody in patient’s serum or antigen in patient specimen
Membrane EIAs incorporate reagents into absorbent membrane

8. Pregnancy Tests Enzyme immunoassay (EIA) test Examples of
OTC pregnancy test kits
Tests for Group A streptococcus
Common features of EIA tests for hCG
Performing EIA test for pregnancy

9. Infectious Mononucleosis
A contagious disease
May have vague clinical symptoms
Can mimic other diseases
Commonly called “mono” or “kissing disease”

10. Infectious Mononucleosis
Result of common infection of lymphocytes by Epstein-Barr virus (EBV)
After primary infection, virus establishes lifelong latency
EBV implicated in other diseases

11. Infectious Mononucleosis
Transmission of EBV
By saliva
Sharing of drinking glasses
Blood transfusion
In closed social groups
Importance of hand washing

12. Infectious Mononucleosis
Symptoms of mononucleosis
Seen most often in children and young adults
Incubation of 7–14 days average
Younger children usually asymptomatic or manifest minor symptoms

13. Infectious Mononucleosis
Symptoms of mononucleosis
Classic symptoms occur when primary infection delayed until second decade of life
Fever, swollen glands, headache, malaise, chest pain, cough, tonsillitis, rash, swollen lymph nodes, swollen spleen
Symptoms last average of 2–4 weeks

14. Infectious Mononucleosis
Treatment of mononucleosis
Primarily supportive
Vaccine not yet available
Diagnosis of infectious mononucleosis
Rapid test kits

15. Infectious Mononucleosis
Watch the video

16. Infectious Mononucleosis
Diagnosis of infectious mononucleosis
Blood test for infectious mononucleosis
Includes WBC count
Evaluation of patient’s lymphocytes
Serological test for infectious mononucleosis
Detection of heterophile antibodies
Combined with tests and clinical findings/patient symptoms
Positive after first week of illness

17. Infectious Mononucleosis
Slide test for infectious mononucleosis
Most common serological test used for IM
Several commercial kits available
Performing the slide agglutination test for IM
Adding reagents
Mixing reagents using wooden applicator

18. Blood Typing
Based on presence or absence of antigens on surface of RBC
Hemagglutination reactions

19. Types of Blood Typing ABO blood typing
Determined by presence or absence of antigens A and B
Determined by slide or tube method

20. Types of Blood Typing Rh blood typing
Routinely performed along with ABO typing
Named for rhesus monkey
Rh factor found on surface of RBC
Rh positive and Rh negative
About 85 percent of North Americans are Rh positive

21. Types of Blood Typing Rh blood typing Can develop antibodies
Importance of knowing Rh blood type
For transfusions
For childbirth

22. Semen Analysis When performed To determine sperm cell count
As part of complete fertility workup
To evaluate effectiveness of vasectomy
To determine paternity
To substantiate rape cases

23. Semen Analysis Reference values Semen composition
Composite solution produced by testes
Spermatozoa suspended in seminal plasma
Variation in composition between different portions of fluid as ejaculated

24. Semen Analysis Altering factors in semen analysis
Several drugs/chemicals
Orchitis
Testicular atrophy
Testicular failure
Obstruction of vas deferens

25. Semen Analysis Altering factors in semen analysis
Cigarette smoking
Coffee drinking
Fever
Procedure for semen analysis

26. Phenylketonuria (PKU) Test
About PKU
Inherited condition
Amino acid phenylalanine is not metabolized
Causes urine to have mousy or musty odor

27. Phenylketonuria (PKU) Test
Routine screening of the newborn
Tests for excess phenylalanine in blood or urine

28. Phenylketonuria (PKU) Test
Blood testing for PKU
Guthrie screening test
Heel-stick capillary blood collected onto “filter paper” test card

29. Phenylketonuria (PKU) Test
Blood testing for PKU
Factors that may influence the Guthrie test
Feeding problems
Failure to ingest sufficient phenylalanine
Premature infants
Drugs taken by mother or infant

30. Phenylketonuria (PKU) Test
Urine testing for PKU
In infants at least 6 weeks old
Obtaining urine sample
Positive urine test should be followed up with blood test for PKU
Other tests performed with PKU, depending on state laws

31. Tuberculosis: Mycobacterium and TB Testing
Morbidity on the rise
Advisory Council for Elimination of Tuberculosis recommends screening high-risk groups
Cause of TB
Mycobacterium tuberculosis
Ziehl-Nielson method of identification

32. Tuberculosis: Mycobacterium and TB Testing
Resistance in mycobacteria
Tolerance for drying and many disinfectants
To most antibiotics
Overcoming bacterial resistance
Susceptible to heat
Killed in milk by pasteurization

33. Tuberculosis: Mycobacterium and TB Testing
Transmission of infectious TB
Highly contagious
Most new cases (75%) occur by inhalation of cough-produced airborne droplets from symptomatic or asymptomatic persons

34. Tuberculosis: Mycobacterium and TB Testing
Transmission of infectious TB
Conditions that contribute to transmission
Poverty
Crowded conditions, such as mental health hospitals and prisons
Poor health or weakened immune systems
Related to rise in AIDS

35. Tuberculosis: Mycobacterium and TB Testing
Diagnosis of TB
Isolation, identification, and diagnosis procedures
Patients with questionable purified protein derivative (PPD) should have chest x-ray
Presence of acid-fast rods in sputum
Vaccination with BCG

36. Tuberculosis: Mycobacterium and TB Testing
Screening for TB: skin testing
May be part of routine examination or prerequisite for school or employment
Mantoux test >>
Reading the test

37. Blood Glucose Fasting blood glucose
Used to screen for diabetes mellitus, Cushing’s syndrome, and acute stress response
Reference glucose values

38. Blood Glucose Two-hour postprandial blood glucose
Performed after eating
Used to screen for diabetes and to monitor insulin dosage
Glucola®
Blood sample taken

39. Blood Glucose Glucose tolerance test
Follows fasting urine and blood samples
Patient consumes glucose test solution
Blood and urine samples taken at timed intervals after ingestion
Symptoms

40. Blood Glucose Automated methods of glucose analysis
HemoCue® Blood-Glucose system
Handheld glucose meters
Glucose controls
Tips for patients selecting appropriate glucose meter
Reflectance photometry analyzers

41. Blood Glucose
Watch the video

42. Blood Glucose Testing profiles Glycosylated hemoglobin
A stable molecule formed when sugar and hemoglobin bind on the RBC
Elevated finding indicates poor glucose control

43. Cholesterol Chemistry of cholesterol
Reference values for total blood cholesterol
Consists of carbon, hydrogen, and oxygen
Saturated fatty acid

44. Cholesterol Functions of cholesterol
Cells use cholesterol to manufacture steroid hormones
Important component of bile and cellular membranes
May accumulate in body and reach dangerous levels
Take in cholesterol when eating meat, eggs, and dairy products

45. Cholesterol Lipoproteins and cholesterol transport Cholesterol testing
High-density lipoprotein (HDL)
Low-density lipoprotein (LDL)
Reference ranges for HDL and LDL cholesterol
Cholesterol testing

46. Triglycerides
Type of lipid found in blood that serve as source of energy
Liver converts fatty acids and glycerol from diet
Adipose tissue

47. Triglycerides Reference values
Factors that influence serum triglyceride levels

48. Blood Chemistry Tests Measure concentration of chemistries in blood
Blood chemistry reference values
Factors that influence serum chemistries
Significance of abnormal blood chemistry levels