biology

Venereal Disease Research Laboratory test

Venereal Disease Research Laboratory test is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Venereal Disease Research Laboratory test rather than just read about it. In short: The Venereal Disease Research Laboratory test (VDRL) is a blood test for syphilis and related non-venereal treponematoses that was developed by the eponymous US laboratory. The VDRL test is used to screen for syphilis (it has high sensitivity), whereas other, more specific tests are used to diagnose the disease.

Key takeaways

Venereal Disease Research Laboratory test belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Venereal Disease Research Laboratory test to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Venereal Disease Research Laboratory test from memory before moving on to harder problems.

Reference excerpt

The Venereal Disease Research Laboratory test (VDRL) is a blood test for syphilis and related non-venereal treponematoses that was developed by the eponymous US laboratory. The VDRL test is used to screen for syphilis (it has high sensitivity), whereas other, more specific tests are used to diagnose the disease.

History The VDRL type test was invented before World War I, with its first iteration being that developed by August Paul von Wasserman with the aid of Albert Neisser in 1906. The VDRL test, as it is largely still done today, was developed in 1946 by Harris, Rosenberg, and Riedel. The lab was renamed to the Treponemal Pathogenesis and Immunology Branch of the United States Public Health Service.

Mechanism The VDRL is a nontreponemal serological screening for syphilis that is also used to assess response to therapy, to detect central nervous system involvement, and as an aid in the diagnosis of congenital syphilis. The basis of the test is that an antibody produced by a patient with syphilis reacts with an extract of ox heart (diphosphatidyl glycerol). It therefore detects anti-cardiolipin antibodies (IgG, IgM or IgA), visualized through foaming of the test tube fluid, or "flocculation". The rapid plasma reagin (RPR) test uses the same antigen as the VDRL, but in that test, it has been bound to several other molecules, including a carbon particle to allow visualization of the flocculation reaction without the need of a microscope. Many other medical conditions can produce false positive results, including some viruses (mononucleosis, hepatitis), drugs, pregnancy, rheumatic fever, rheumatoid arthritis, lupus, and leprosy. The syphilis anti-cardiolipin antibodies are beta-2 glycoprotein independent, whereas those that occur in antiphospholipid syndrome (associated to lupus for example) are beta-2 glycoprotein dependent, and this can be used to tell them apart in an ELISA assay. This test is very useful as the trend of titres are correlated to disease activity (i.e. falling titres indicate successful treatment). It has a very good sensitivity for syphilis, except in late tertiary form.

Other tests

There are a number of treponemal-specific tests such as the fluorescent treponemal antibody-absorption (FTA-ABS) test, T. pallidum hemagglutination assays (TPHA), and the microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after another method tests positive for the syphilis bacteria. The MHA-TP test detects antibodies to the bacteria that cause syphilis and can be used to detect syphilis in all stages, except during the first 3 to 4 weeks. This test is not done on spinal fluid. The MHA-TP test is rarely used any more. Treponema pallidum particle agglutination assay (TP-PA) and the Toluidine red unheated serum test (TRUST), which may be used to confirm a positive VDRL result, are more specific for syphilis than non-treponemal tests and in the presence of a positive test, more likely indicate active infection. Unfortunately, other treponemal infections such as yaws, bejel, and pinta and possibly nonpathogenic commensal treponemes can result in a positive. Not all these disease are venereal; it has been recommended that a careful explanation of this fact be included with test results.

References

Illustrations

Worked examples

Example 1 — a first encounter with Venereal Disease Research Laboratory test

Start with the simplest possible case. Write down what Venereal Disease Research Laboratory test claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Venereal Disease Research Laboratory test before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Venereal Disease Research Laboratory test ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Venereal Disease Research Laboratory test

In research: Venereal Disease Research Laboratory test appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Venereal Disease Research Laboratory test in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Venereal Disease Research Laboratory test is common in secondary-school and first-year university syllabi. It links to neighbouring topics Infectious disease blood tests, Syphilis, so understanding it makes those chapters shorter.
In everyday life: Look for Venereal Disease Research Laboratory test outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Venereal Disease Research Laboratory test in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Venereal Disease Research Laboratory test means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Venereal Disease Research Laboratory test in simple terms?

Why does Venereal Disease Research Laboratory test matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Venereal Disease Research Laboratory test?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Venereal Disease Research Laboratory test.