Diagnostic and Lab Findings Flashcards
What does the Oregon state public health lab screen
Dried blood samples collected at birth for 29 main diseases. SCID was added to this core list in 2014
What is a common characteristic of newborns with SCID
Have absent or extremely low production of naive T cells from the thymus
How are newborns screened for SCID
TREC test - stands for T-cell receptor excision circles.
How is the TREC test obtained
From a dried blood spot sample already collected for routine newborn screening
What is the normal TREC number for babies without SCID
10% of their total T-cell numbers
What are the TREC numbers for babies with SCID
The TREC will be very low or undetectable
Importance of early identification of SCID
- Est dx and start lifesaving tx immediately
- Avoid inefficient costly dangerous dx
- Provide families with genetic diagnosis/advice on reproductive risk
- Learn incidence and true spectrum of SCID
- Educate providers/public about SCID
- Allows multiple facility to collaborate on trials to determine optimal tx
Barriers to early dx without screening
- SCID is rare
- Infections are common in all infants, not just those with SCID
- > 80% of cases are sporadic, w/no fam hx
- SCID infants are protected by maternal IgG during first months of life
- Presentation is variable due to gene defect and environment factors
ELISA
HIV test. Enzyme linked immunosorbent assay. Do this test first, very accurate, but follow with western blot for an almost 100% diagnosis. Detects the presence of an antigen (in this case HIV). Antibody/antigen binding
Western blot
Confirmatory test after the ELISA. If positive, pt has almost a 100% of having HIV. Identifies specific amino acid sequences in proteins (aka in the virus)
CBC w/diff
Complete blood count. Will show different concentrations of lymphoctyes. Will show if there is a combine T and B defect
Lymphocyte subsets for CD cells
Tells you which type of lymphocyte is deficient. One or more lymphocyte (B, T, NK) may be deficient.
CD3, CD4, CD19,
If you have decrease in both CD4 and CD8 on a subset test what may that indicate
- Combined immunodeficiency syndrome
2. DiGeorge syndrome
If you have a decrease in just CD4 on a subset test what might that indicate
HIV
Lymphocyte stimulation with mitogens and antigens for asssessment of lymphocyte function
Studies that measure T cell proliferation in the blood in response to mitogens and antigens. If low, means that there is a very low immune system response
