LABORATORY TESTS

• The purposes of Diagnosis and Laboratory Tests are

  • Screening 
  • Diagnosis 
  • Monitoring 
  • Prognosis
  • Patient Management
• Screening consists of studying patients who do not yet present any signs or symptoms of a specific illness in order to find out if it has begun to quietly develop 
• Screening is to identify risk factors for disease and to detect occult disease in asymptomatic persons 
• Examples of Tests used to screen patient disease status would be cancer screening and newborn screening
• Cancer screening - Mammogram, Pap and HPV testing, Prostate-specific antigen tests
• newborn screening

  • Congenital Hypothyroidism 
  • Congenital Adrenal Hyperplasia 
  • Galactosemia
  • Phenylketonuria 
  • G6PD deficiency
• Diagnosis is the process of finding out if a patient has a specific disease
• Diagnosis is to help establish or exclude the presence of disease in symptomatic persons 
• Good examples of Diagnosis: angiogram
• Tests to diagnose asthma: spirometer and checking LEV1 or Forced Vital Capacity
• Some tests assist for diagnosis in:

  • early diagnosis after onset of symptoms and signs 
  • developing a differential diagnosis 

  determine the stage or activity of disease
• Patient monitoring includes monitoring and prognosis
• • Diagnostic and laboratory tests can help…

  1. evaluate the severity of disease 
  2. estimate prognosis 
  3. monitor the course of disease (progression, stability, or resolution) (how well they are doing sa disease nila)
  4. detect disease recurrence 
  5. select drugs and adjust therapy (response to treatment)
• DM test is Glycosylated hemoglobin (HBA1c)
• Heparin Anticoagulation test is PTT (Partial Thromboplastin Time)
• CKD Test is Creatinine levels 
• Hyperlipidemia tests: Lipid profile
• IDA test: Reticulocyte count and hemoglobin
• Normal range is result falls within a predetermined range of values, reference values or cut-off points 
• Reference range: based on results culled from a select normal populations
• Normal variations in Reference Intervals:

  • Newborns
  • Children
  • Pregnant women
  • Geriatric population
  • Adult men/women
• Reference ranges vary from lab to lab and it may be institution-specific 
• Laboratory test result May vary as a result of 

  • Inter-individual factor 
  • Clinical lab methods 
  • Reagents 
  • Analytical procedure 
  • Equipment 
  • Changes in analytical method
• Positive test result: means that the substance or condition being tested for was found.
• • Positive test results also can mean that the amount of a substance being tested for is higher or lower than normal
• Negative Test results means that the substance or condition being tested for was not found.
• • Negative results can also mean that the substance being tested for was present in a normal amount
• Inconclusive test results: are those that are not clearly positive. 
• False-positive test results: is one that shows a disease or condition is present when it is not present.
• • A false-positive test result may suggest that a person has the disease or condition when he or she does not have it
• False negative test results: is one that does not detect what is being tested for even though it is present
• A false-negative test result may suggest that a person does not have a disease or condition being tested for when he or she does have it
• Complete blood count (CBC), which includes:

  • White blood cell count (WBC) 
  • Red blood cell count (RBC) 
  • Platelet count 
  • Hematocrit red blood cell volume (HCT)
  • Hemoglobin concentration (HB). This is the oxygen-carrying protein in red blood cells. 
  • Differential white blood count 
  • Red blood cell indices (measurements)
• Uses of CBC:  To aid in diagnosing anemia, certain cancers of the blood, inflammatory diseases, and to monitor blood loss and infection
• Platelet count (usually done as part of the CBC) is to diagnose and/or to monitor certain types of bleeding and clotting disorders
• Prothrombin time (PT) Partial Thromboplastin Time (PTT) International Normalized Ratio (INR) is to evaluate bleeding and clotting disorders and to monitor anticoagulation (anticlotting) therapies
• RBC reference range: 4-6 million/uL
• Hb:

   Male: 14-18 g/dL

   Female: 12-16 g/dL

   Hct

   Male: 42-54%

   Female: 38-46%
• Hb and Hct:

   Low values

  • Anemia
  • Massive blood loss 

   High Values 

  • Polycythemia (blood disorder where nasosobrahan ng pagproduce yung body ng RBC)

  Dehydration/ severe blood loss (severe= may dehydration na)
• Reference range:  MVC: 84-99fL

   MCH: 26-32 pg

   MCHC: 30-36 g/dL