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AFBAcid-fast bacillus
AIDSAcquired immunodeficiency syndrome
ALTAlanine aminotransferase
ANAAntinuclear antibody
ASTAspartate aminotransferase
CBCComplete blood cell count
CFComplement fixation
CHFCongestive heart failure
CKCreatine kinase
CNSCentral nervous system
CSFCerebrospinal fluid
CXRChest x-ray
CYPCytochrome P450
DiffDifferential cell count
EDTAEthylenediaminetetraacetic acid (edetate)
ELISAEnzyme-linked immunosorbent assay
GNRGram-negative rod
GNCBGram-negative coccobacillus
GPCGram-positive coccus
GVCBGram-variable coccobacillus
HLAHuman leukocyte antigen
INRInternational Normalized Ratio
MNMononuclear cell
MRIMagnetic resonance imaging
NPONothing by mouth (nil per os)
PCRPolymerase chain reaction
PMNPolymorphonuclear neutrophil (leukocyte)
POOrally (per os)
PTHParathyroid hormone
RBCRed blood cell
RPRRapid plasma reagin (syphilis test)
SIADHSyndrome of inappropriate antidiuretic hormone (secretion)
SLESystemic lupus erythematosus
T4Tetraiodothyronine (thyroxine)
TSHThyroid-stimulating hormone
VDRLVenereal Disease Research Laboratory (syphilis test)
WBCWhite blood cell
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The clinician's main task is to make reasoned decisions about patient care despite incomplete clinical information and uncertainty about clinical outcomes. Although data elicited from the history and physical examination are often sufficient for making a diagnosis or for guiding therapy, more information may be required. In these situations, clinicians often turn to diagnostic tests for help.


When used appropriately, diagnostic tests can be of great assistance to the clinician. Tests can be helpful for screening, ie, to identify risk factors for disease and to detect occult disease in asymptomatic persons. Identification of risk factors may allow early intervention to prevent disease occurrence, and early detection of occult disease may reduce disease morbidity and mortality through early treatment. Blood pressure measurement is recommended for preventive care of asymptomatic low risk adults. Screening for breast, cervix, and colon cancer is also recommended, whereas screening for prostate cancer and lung cancer remains controversial. Optimal screening tests should meet the criteria listed in Table 1–1.

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Table 1–1. Criteria for Use of Screening Procedures.

Tests can also be helpful for diagnosis, ie, to help establish or exclude the presence of disease in symptomatic persons. Some tests assist in early diagnosis after onset of symptoms and signs; others assist in developing a differential diagnosis; ...

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