{"id":2001,"date":"2020-11-27T17:28:04","date_gmt":"2020-11-27T10:28:04","guid":{"rendered":"https:\/\/drsoaraweeurology.com\/?p=2001"},"modified":"2026-08-15T00:21:24","modified_gmt":"2026-08-14T17:21:24","slug":"syphilis-verwechslungstests","status":"publish","type":"post","link":"https:\/\/drsoaraweeurology.com\/de\/2020\/11\/27\/syphilis-confusion-tests\/","title":{"rendered":"Syphilis Blood Tests Explained: Why There Are Two Kinds"},"content":{"rendered":"\n<div class=\"wp-block-columns coblocks-author-columns has-background is-layout-flex wp-container-core-columns-is-layout-52275889 wp-block-columns-is-layout-flex\" style=\"background-color:#8C8C971A;padding-top:2.5rem;padding-right:2.5rem;padding-bottom:2.5rem;padding-left:2.5rem\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:25%\">\n<figure class=\"wp-block-image size-full is-style-rounded\"><img data-recalc-dims=\"1\" fetchpriority=\"high\" decoding=\"async\" width=\"800\" height=\"800\" data-attachment-id=\"7037\" data-permalink=\"https:\/\/drsoaraweeurology.com\/de\/new-photo-2024\/\" data-orig-file=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2023\/12\/New-Photo-2024.png?fit=800%2C800&amp;ssl=1\" data-orig-size=\"800,800\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"Dr. Soarawee Weerasopone \u2014 Board-Certified Urologist in Bangkok, Thailand\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Dr. Soarawee Weerasopone \u2014 Board-Certified Urologist in Bangkok, Thailand&lt;\/p&gt;\n\" 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2.578-2.016 5.025-5.325 5.025h-3.919V7.416zm1.444 1.303v7.444h2.297c3.272 0 4.022-2.484 4.022-3.722 0-2.016-1.284-3.722-4.097-3.722h-2.222z\"\/>\n    <\/svg>\n  <\/a>\n  \n  <a href=\"https:\/\/scholar.google.com\/citations?user=lTgsRMUAAAAJ&#038;hl=en\" \n     target=\"_blank\" \n     rel=\"noopener\"\n     title=\"Google Scholar\"\n     aria-label=\"View Google Scholar Profile\"\n     style=\"text-decoration: none; color: #4285F4; transition: transform 0.2s; display: inline-block;\"\n     onmouseover=\"this.style.transform='scale(1.15)'\"\n     onmouseout=\"this.style.transform='scale(1)'\">\n    <svg width=\"28\" height=\"28\" viewBox=\"0 0 24 24\" fill=\"currentColor\">\n      <path d=\"M5.242 13.769L0.5 9.5 12 1l11.5 8.5-4.742 4.269C17.548 11.249 14.978 9.5 12 9.5c-2.977 0-5.548 1.748-6.758 4.269zM12 10a7 7 0 1 0 0 14 7 7 0 0 0 0-14z\"\/>\n    <\/svg>\n  <\/a>\n  \n<\/div>\n\n\n\n<p class=\"has-drop-cap wp-block-paragraph\">Syphilis is one of the sexually transmitted infections I see regularly. How it presents depends on the stage \u2014 a painless genital ulcer early on, a rash on the palms and soles later. A blood test is the only way to confirm the diagnosis, and that is where the confusion starts, because <a href=\"https:\/\/pubmed.ncbi.nlm.nih.gov\/27606153\/\">there are two different families of blood test<\/a> and each has its own strengths and limits.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This matters more than a technical detail. Patients who receive a positive result without a full explanation often leave badly frightened, and end up going from clinic to clinic looking for a second opinion that says something different. Understanding what each test actually measures usually removes the fear entirely.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img data-recalc-dims=\"1\" decoding=\"async\" width=\"800\" height=\"532\" data-attachment-id=\"2012\" data-permalink=\"https:\/\/drsoaraweeurology.com\/de\/2020\/11\/27\/syphilis-confusion-tests\/close-up-of-doctor-hand-holding-blood-sample-copy-space\/\" data-orig-file=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?fit=1200%2C798&amp;ssl=1\" data-orig-size=\"1200,798\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;4&quot;,&quot;credit&quot;:&quot;NATHAPHAT&quot;,&quot;camera&quot;:&quot;NIKON Z 6&quot;,&quot;caption&quot;:&quot;Close up of doctor hand holding blood sample. Copy space.&quot;,&quot;created_timestamp&quot;:&quot;1572076848&quot;,&quot;copyright&quot;:&quot;NAMPIX&quot;,&quot;focal_length&quot;:&quot;105&quot;,&quot;iso&quot;:&quot;100&quot;,&quot;shutter_speed&quot;:&quot;0.1&quot;,&quot;title&quot;:&quot;Close up of doctor hand holding blood sample. Copy space.&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"The only way for making syphilis diagnosis is blood test\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;The only way for making syphilis diagnosis is blood test &lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?fit=800%2C532&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?resize=800%2C532&#038;ssl=1\" alt=\"A blood sample being taken for syphilis serology testing\" class=\"wp-image-2012\" srcset=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?w=1200&amp;ssl=1 1200w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?resize=300%2C200&amp;ssl=1 300w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?resize=1024%2C681&amp;ssl=1 1024w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?resize=768%2C511&amp;ssl=1 768w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Blood-test.jpg?resize=16%2C12&amp;ssl=1 16w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption class=\"wp-element-caption\">A blood test is the only way to confirm a diagnosis of syphilis.<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">1. Nontreponemal tests \u2014 the screening tests<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">These are used first, when syphilis is suspected. Their strength is that they reflect <strong>active<\/strong> infection, which also makes them the tests used to check whether treatment is working.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>VDRL (Venereal Disease Research Laboratory)<\/li>\n\n\n\n<li>RPR (Rapid Plasma Reagin)<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">Their weakness is that they can turn positive when there is no syphilis at all \u2014 a <a href=\"https:\/\/drsoaraweeurology.com\/2021\/10\/22\/vdrl-false-positive-test-causes\/\">biological false positive<\/a>, which several other conditions can cause. That is precisely why a positive screening test is never the end of the story. They can also read falsely negative very early in infection, before antibodies have developed, so a recent exposure with a negative result may need repeating.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">2. Treponemal tests \u2014 the confirmation tests<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">If a VDRL or RPR comes back positive, the diagnosis has to be confirmed with a treponemal test.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>TP-PA (Treponema Pallidum Particle Agglutination)<\/li>\n\n\n\n<li>FTA-ABS (Fluorescent Treponemal Antibody Absorbed)<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">These are highly accurate for syphilis. Their limitation is the one that causes the most distress: <strong>a treponemal test stays positive for the rest of your life, even after the infection has been completely cured.<\/strong> It tells you that you have encountered syphilis at some point \u2014 not that you have it now. This is why treatment can never be judged by a treponemal test alone.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Reading the two together<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The practical rule is simple once you have it: the <strong>confirmation test answers whether it was ever syphilis<\/strong>, and the <strong>screening test answers whether it is active now and whether the treatment is working<\/strong>. Treatment response is followed by watching the VDRL or RPR titre fall over the months after treatment. A permanently positive treponemal test alongside a falling titre is exactly what a successfully treated patient looks like.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img data-recalc-dims=\"1\" decoding=\"async\" width=\"800\" height=\"800\" data-attachment-id=\"2014\" data-permalink=\"https:\/\/drsoaraweeurology.com\/de\/2020\/11\/27\/syphilis-confusion-tests\/happy-doctor\/\" data-orig-file=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?fit=1200%2C1200&amp;ssl=1\" data-orig-size=\"1200,1200\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Good understanding about the tests bring the best outcome and strengthen Doctor-Patient relationship\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Good understanding about the tests bring the best outcome and strengthen Doctor-Patient relationship&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?fit=800%2C800&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=800%2C800&#038;ssl=1\" alt=\"A doctor explaining syphilis blood test results to a patient during consultation\" class=\"wp-image-2014\" srcset=\"https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?w=1200&amp;ssl=1 1200w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=300%2C300&amp;ssl=1 300w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=1024%2C1024&amp;ssl=1 1024w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=150%2C150&amp;ssl=1 150w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=768%2C768&amp;ssl=1 768w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=12%2C12&amp;ssl=1 12w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=800%2C800&amp;ssl=1 800w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=400%2C400&amp;ssl=1 400w, https:\/\/i0.wp.com\/drsoaraweeurology.com\/wp-content\/uploads\/2020\/11\/Happy-doctor.jpg?resize=200%2C200&amp;ssl=1 200w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><figcaption class=\"wp-element-caption\">Understanding the tests removes most of the fear that a positive result causes.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Two practical points that follow from all this. A confirmed diagnosis means <strong>current sexual partners need testing and treatment as well<\/strong>, whatever your own result now shows. And because syphilis travels in company, testing for other sexually transmitted infections at the same time is standard rather than an extra.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Syphilis is a very treatable infection \u2014 <a href=\"https:\/\/drsoaraweeurology.com\/2021\/10\/08\/syphilis-correct-way-deal-with\/\">treatment is straightforward when it is done correctly<\/a>. What turns it into a frightening experience is usually not the disease but the test results arriving without an explanation. If you have a positive result and nobody has walked you through what it means, ask. Once you can read your own results, the panic tends to disappear.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If you have concerns about syphilis blood test results or need diagnosis and treatment for a sexually transmitted infection, Dr. Soarawee Weerasopone offers confidential specialist consultations at Bangkok Hospital Headquarters. <a href=\"https:\/\/www.bangkokhospital.com\/en\/bangkok\/doctor\/dr-soarawee-weerasopone-2\">Book a Consultation<\/a>. Appointments at Samitivej Sriracha Hospital can be arranged by calling the Urology department on <a href=\"tel:0880221445\">088-022-1445<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions about Syphilis Blood Tests<\/h2>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1\"><strong class=\"schema-faq-question\">What is the difference between nontreponemal and treponemal syphilis tests?<\/strong> <p class=\"schema-faq-answer\">Nontreponemal tests (VDRL, RPR) are used as screening tests to detect active syphilis infection and to monitor treatment response. Treponemal tests (TP-PA, FTA-ABS) are confirmation tests that are highly specific for syphilis but remain positive for life even after successful treatment, so they cannot be used alone to assess treatment outcome.<\/p><\/div> <div class=\"schema-faq-section\" id=\"faq-question-2\"><strong class=\"schema-faq-question\">If my VDRL or RPR is positive, does it mean I have syphilis?<\/strong> <p class=\"schema-faq-answer\">A positive VDRL or RPR is a strong indicator but not a definitive diagnosis. These screening tests can occasionally produce false positives due to other conditions such as autoimmune diseases or viral infections. A confirmatory treponemal test (TP-PA or FTA-ABS) is always required to make a definitive diagnosis of syphilis.<\/p><\/div> <div class=\"schema-faq-section\" id=\"faq-question-3\"><strong class=\"schema-faq-question\">Why does my treponemal test stay positive even after treatment?<\/strong> <p class=\"schema-faq-answer\">Treponemal tests detect specific antibodies against the syphilis bacterium that persist in the bloodstream for life once produced, even after the infection has been completely cured. This is a normal finding and does not mean the infection is still active. Treatment success is monitored using nontreponemal tests (VDRL or RPR), which should show a declining titer after effective treatment.<\/p><\/div> <div class=\"schema-faq-section\" id=\"faq-question-4\"><strong class=\"schema-faq-question\">How do doctors know if syphilis treatment is working?<\/strong> <p class=\"schema-faq-answer\">Treatment response is tracked by monitoring the VDRL or RPR titer over time. After successful treatment, the nontreponemal titer should decrease fourfold or more within 6&#8211;12 months. A stable or rising titer may indicate treatment failure or reinfection, requiring further evaluation by a specialist.<\/p><\/div> <div class=\"schema-faq-section\" id=\"faq-question-5\"><strong class=\"schema-faq-question\">Is syphilis curable?<\/strong> <p class=\"schema-faq-answer\">Yes, syphilis is highly curable, especially when diagnosed and treated early. The standard treatment is penicillin G injection, with the dose and duration depending on the stage of infection. Early diagnosis, correct treatment, and regular follow-up blood tests are essential to ensure complete cure and prevent complications or transmission to partners. Current sexual partners should be tested and treated as well.<\/p><\/div><\/div>\n\n\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"MedicalWebPage\",\n      \"@id\": \"https:\/\/drsoaraweeurology.com\/2020\/11\/27\/syphilis-confusion-tests\/#webpage\",\n      \"url\": \"https:\/\/drsoaraweeurology.com\/2020\/11\/27\/syphilis-confusion-tests\/\",\n      \"name\": \"Syphilis Blood Tests Explained: Why There Are Two Kinds\",\n      \"description\": \"Why syphilis needs two different families of blood test: nontreponemal screening tests (VDRL, RPR) that reflect active infection and track treatment, and treponemal confirmation tests (TP-PA, FTA-ABS) that stay positive for life. How to read them together.\",\n      \"inLanguage\": \"en\",\n      \"lastReviewed\": \"2026-08-13\",\n      \"specialty\": \"https:\/\/schema.org\/Urologic\",\n      \"medicalAudience\": \"https:\/\/schema.org\/Patient\",\n      \"about\": {\n        \"@type\": \"MedicalCondition\",\n        \"name\": \"Syphilis\"\n      },\n      \"author\": {\n        \"@type\": \"Physician\",\n        \"name\": \"Dr. Soarawee Weerasopone\",\n        \"medicalSpecialty\": \"https:\/\/schema.org\/Urologic\",\n        \"url\": \"https:\/\/drsoaraweeurology.com\/\"\n      }\n    },\n    {\n      \"@type\": \"MedicalTest\",\n      \"@id\": \"https:\/\/drsoaraweeurology.com\/2020\/11\/27\/syphilis-confusion-tests\/#nontreponemal\",\n      \"name\": \"Nontreponemal syphilis tests (VDRL, RPR)\",\n      \"description\": \"Screening tests used first when syphilis is suspected. They reflect active infection, which is why they are also used to judge whether treatment is working: after effective treatment the titre should fall fourfold or more within 6 to 12 months, while a stable or rising titre suggests treatment failure or reinfection. They can produce a biological false positive in the absence of syphilis, which is why a positive result always requires confirmation, and they can read falsely negative very early in infection before antibodies have developed.\",\n      \"usedToDiagnose\": {\n        \"@type\": \"MedicalCondition\",\n        \"name\": \"Syphilis\"\n      }\n    },\n    {\n      \"@type\": \"MedicalTest\",\n      \"@id\": \"https:\/\/drsoaraweeurology.com\/2020\/11\/27\/syphilis-confusion-tests\/#treponemal\",\n      \"name\": \"Treponemal syphilis tests (TP-PA, FTA-ABS)\",\n      \"description\": \"Confirmation tests, highly specific for syphilis, performed after a positive screening test. Their key limitation is that they remain positive for life even after the infection has been completely cured, so a positive result means the person has encountered syphilis at some point rather than that they have it now. Treatment response can never be judged from a treponemal test alone. A permanently positive treponemal test alongside a falling nontreponemal titre is what a successfully treated patient looks like.\",\n      \"usedToDiagnose\": {\n        \"@type\": \"MedicalCondition\",\n        \"name\": \"Syphilis\"\n      }\n    },\n    {\n      \"@type\": \"MedicalCondition\",\n      \"@id\": \"https:\/\/drsoaraweeurology.com\/2020\/11\/27\/syphilis-confusion-tests\/#syphilis\",\n      \"name\": \"Syphilis\",\n      \"description\": \"A sexually transmitted bacterial infection whose presentation depends on the stage: a painless genital ulcer early on, a rash on the palms and soles later. It is highly curable, particularly when diagnosed early. 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It is intended for educational purposes only and does not constitute medical advice. Blood test results must be interpreted by a doctor who knows your history \u2014 do not draw conclusions about your own results from this article alone. No medical advice, diagnosis or prescription is provided through personal messaging channels. Always consult a qualified healthcare professional before starting any medical treatment.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A positive syphilis test does not always mean an active infection \u2014 and one of the two tests stays positive for the rest of your life even after you are cured. Dr. Soarawee Weerasopone, urologist at Bangkok Hospital, explains what each test measures and how to read them together.<\/p>","protected":false},"author":185281453,"featured_media":10101,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"Confused about syphilis blood tests? 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