22 Laboratory studies Flashcards by brian langford

What are the only Ag-specific for syphilis

FTA-ABS, MHA-TA

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What test is used to screen for syphilis

VDRL

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T/F: FTA-ABS become negative once pt has been adequately tx for syphilis

False

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What are some common labs in pts with sarcoidosis

Hypergammaglobulinemia, elevated LFTs, Ca, ESR, and ACE

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What is an abnl Schirmer test

Less than 5 mm wetting after 5 mins; less than 10 mm wetting after stimulation with 10% ammonia

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What tests used to dx Sjogren’s

Minor salivary gland bx showing mononuclear cell infiltration, SSA, SSB, ANA, RF

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What lab test is a/w lymphoproliferative malignancy in pts w/ Sjogrens

Decreased level of serum IgM

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Lab findings in pt with relapsing polychondritis

Elevated ESR, moderate leukocytosis, mild-to-mod anemia

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What lab test is most specific for Wegener’s

c-ANCA

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What is the significance of a rising c-ANCA titer in pt w/ Wegener’s

Usu indicates a relapse of active dz

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HLA-DW4 Ab are m/c seen in which autoimmune dz

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What auto-Ab is present in 75% of pts with RA

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What is the most specific test for the dx of autoimmune SNHL

Western blot assay for 68 kD inner ear antigen (Otoblot) (95% specific)

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The 68 kDa Ag is thought to represent what protein

Heat shock protein 70

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What percent of pts with immune-mediated Meniere’s dz will have a positive anti-68-kD western blot test

30-50%

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What is the most specific test for the dx of Cogan’s syndrome

Western blot assay for 55 kD inner ear antigen

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Pt w/ Cogan’s syndrome usu have elevated titers to what organism

Chlamydia

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What is the latency period for developing antibodies to hepatitis C

up to 4 months

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What is the latency period for seroconversion following exposure to HIV

6-12 months

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What adjunctive test should be performed in a female with suspected JNA

chromosome analysis

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What test is used to dx pertussis

Cx from NP using a Dacron or calcium alginate swab placed on a Regan-Lowe or Bordet-Gengou agar plate

What is the sensitivity of this test

80% (less if already on antibiotics)

What tests confirm the dx of infectious mono

Blood smear showing atypical mononuclear cells and a positive Paul-Bunnell test (elevated heterophile titer of EBV)

What is most useful study of non-TB mycobacterial adenitis of H&N region in kids

What test should be performed in a pt w/ suspected AFS who does not have classic findings on CT scan or + middle meatal cx

aspergillus skin test and precipitins

How is congenital CMV dx in newborn

ID of serum anti-CMV IgM, "owl-eye" bodies in urinary sediment, and intracerebral calcifications on radiographs

What is most accurate method of determining if otorrhea is CSF

B2 transferrin

What are the characteristics of CSF in presence of meningitis

Elevated protein, WBC, and pressure; dec GLC

What lab tests can be used to dx CSF leak

Measurement of GLC (nasal secretions are devoid of GLC), B2 transferrin

What is the single best measure of nutritional status

serum albumin level

What serum albumin level is a/w malnutrition

Less than 3 g/dL

Which serum proteins can be used to assess short-term nutritional status

Transferrin (1/2 life 8-9 days), prealbumin (1/2 life 2 days), retinal-binding globulin (1/2 life 12 hrs)

All pts w/ paraganglioma should be tested for mutations in which gene?

SDH (succinate dehydrogenase)

What are the m/c immunologic findings among pts with NP CA

Elevated IgA and IgG Ab against the viral capsid Ag of EBV

What is the role of EBV titers in pts with NP CA

“May be a valuable screening tool in high-risk populations and can help establish the diagnosis of NPC in the patient with an unknown primary. In patients with type I disease, EBV titers are not elevated and have no prognostic significance.

“What percent of patients with WHO types II and III tumors have abnormally increased titers to EBV VCA and NA?

80-90%

What test provides prognostic info in pts with NP CA

Antibody-dependent cellular cytotoxicity (ADCC) assay

How does this assay predict survival

low levels are a/w worse prog

How do you test for multiple myeloma in pt with extramedullary plasmacytoma

Measure serum M-protein and urine Bence Jones protein; bone survey; bone marrow bx

What test is used to distinguish a hypothalamic defect from a pituitary defect in a pt w/ hypothyroidism

The thyrotopin-releasing hormone (TRH) stimulation test

T/F: thyroglobulin levels should be obtained prior to performing FNA on a thyroid nodule

True: FNA will falsely elevate thyroglobulin levels

What is the purpose of obtaining a thyroglobulin level prior to thyroidectomy

It has been shown to correlate well with histologic tumor type and is useful as a marker for tumor recurrence

What test should be ordered in pt w/ elevated TSH

Antimicrosomal Ab (antithyroperoxidase level) to r/o Hashimoto's thyroiditis

What lab test should be obtained in pts with FMH of medullary thyroid carcinoma

Calcitonin

What lab w/u is needed in pts with MTC

Basal and pentagastrin stimulated calcitonin levels, serum CA, 24 hr urine catecholamines, VMA, and metanephrine, +/- CEA

What are the histochemical characteristics of MTC

Congo red dye positive, apple-green birefringence consistent with amyloid; immunohistochemistry positive for cytokeratins, CEA, and calcitonin.

What is the false negative rate of RET analysis

What is the most accurate test for dx of primary HPTH

Measurement of intact PTH

Why is measurement of C-terminal of PTH not accurate for dx of 2ndary HPTH

“C-terminal fragments are cleared by the kidney; elevation may indicate either renal insufficiency or hyperparathyroidism.”

“What is the difference in the Ca/Cr clearance ratio in someone with FHH and someone with primary hyperparathyroidism?

“Ca/Cr clearance <0.01 in FHH; >0.02 in primary hyperparathyroidism.