# Paired sFlt-1 and PlGF immunoassays Technology · id `maternal:sflt1-plgf-immunoassay` · Maternal & Newborn Atlas · release `15708f235d73cd42` (public) > General information from published sources, not medical advice, and not reviewed by clinicians. Check the cited source before relying on anything here. The atlas's own text and curation may be reused under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0, https://creativecommons.org/licenses/by-nc/4.0/): credit the atlas, and do not use it commercially. See the atlas About page. Text quoted from a source stays under that source's own terms, given as the source's reuse\_basis. The atlas's reuse terms do not cover it. The downloads list each quotation with its source in third\_party\_quotations. Browse, life stage: Pregnancy ## In plain language Two blood tests run on the same sample in a laboratory machine, one for sFlt-1 and one for placental growth factor (PlGF), with the result reported as the ratio of the two. Different companies build the pair in different ways. This page describes the method, not any one company's product, and not whether any use of the result is recommended. ## Technical summary Quantitative immunoassays for sFlt-1 and PlGF, reported as the sFlt-1/PlGF ratio, in human serum (Elecsys) or in serum or K2-EDTA plasma (KRYPTOR). Two detection methods appear in the sources read. The Roche Elecsys pair uses electrochemiluminescence (ECLIA) on cobas e analyzers. The B·R·A·H·M·S KRYPTOR pair uses Time-Resolved Amplified Cryptate Emission (TRACE) technology. In the US, tests of this kind that are indicated as a prognostic aid are classified under 21 CFR 862.1602 as a prognostic test for development or progression of pre-eclampsia, Class II with special controls, and the regulation says such a device is "not intended for diagnosis of any disease". De Novo request DEN220027, for the KRYPTOR system, was granted under the same regulation number and product code (QWH). NICE HTG630 reports that the company labelling presents the Elecsys ratio test as an aid to diagnosing pre-eclampsia. Both statements are shown here and this record does not resolve them. NICE assessed named products under its own indications in HTG630. ## Claims, with the population each applies to ## Context: Hospitalized for a hypertensive disorder of pregnancy, singleton pregnancy, 23 weeks 0 days to 34 weeks 6 days (US labelling of K241453) Recipient: Maternal; Population: Pregnant women with a singleton pregnancy, hospitalized for a hypertensive disorder of pregnancy (pre-eclampsia, chronic hypertension with or without superimposed pre-eclampsia, or gestational hypertension), at 23 weeks 0 days to 34 weeks 6 days.; Care setting: Hospital. The indication is for women hospitalized for the disorder.; Geography: United States (FDA labelling); Life stage: Pregnancy, 23 weeks 0 days to 34 weeks 6 days; Gestational age: 23 weeks 0 days (161 days) to 34 weeks 6 days (244 days); Postnatal age: Not reported; Follow-up: Two weeks from testing, the window in the indication for developing pre-eclampsia with severe features ### FDA granted De Novo request DEN220027 for the B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System, from Brahms GmbH, part of Thermo Fisher Scientific, on 2023-05-18. The FDA record carries product code QWH and 21 CFR 862.1602, the regulation for a prognostic test for development or progression of pre-eclampsia, which is Class II with special controls. FDA's later 510(k) summary for the Elecsys test names this KRYPTOR system as its predicate device. - Category: Regulatory - Evidence stage: Evidence stage not applicable - Certainty: Certainty not assessed - Applies to: Recipient: Maternal; Population: Pregnant women with a singleton pregnancy, hospitalized for a hypertensive disorder of pregnancy (pre-eclampsia, chronic hypertension with or without superimposed pre-eclampsia, or gestational hypertension), at 23 weeks 0 days to 34 weeks 6 days.; Care setting: Hospital. The indication is for women hospitalized for the disorder.; Geography: United States (FDA labelling); Life stage: Pregnancy, 23 weeks 0 days to 34 weeks 6 days; Gestational age: 23 weeks 0 days (161 days) to 34 weeks 6 days (244 days); Postnatal age: Not reported; Follow-up: Two weeks from testing, the window in the indication for developing pre-eclampsia with severe features - Limitations: A De Novo grant is not a recommendation to use the test. NICE HTG630 recommendation 1.6 does not recommend the BRAHMS KRYPTOR ratio test for routine NHS use, so a US grant and an English statement of non-recommendation can both hold. No product record for the KRYPTOR system exists, so no regulatory decision record is written for it. The decision summary PDF was fetched, but its scanned text has character errors in trade names, so the facts here come from the openFDA record, the denovo.cfm page and the eCFR text. The FDA context of the Elecsys clearance is reused only because this claim concerns the same device type, although the KRYPTOR indication differs from the Elecsys one. Roche's K241453 510(k) Summary prints the KRYPTOR indication in Table 1, predicate column. It reads "within 2 weeks of presentation" where the Elecsys indication reads "within two weeks from testing", it refers to "as defined by American College of Obstetricians and Gynecologists guidelines" for severe features, and it accepts "human serum and plasma (K2 EDTA)" where the Elecsys indication names human serum. The De Novo decision summary was not used for this indication. - Last checked: 2026-10-12 - Sources: 1. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: results\[0\].k\_number. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: bf1f58d99ebe7cfcfd2785421eb073851fab2fc8b5bb4dacf2d0e89edb5be37e. How it applies: The De Novo number as openFDA records it. 2. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: results\[0\].decision\_date. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: bf1f58d99ebe7cfcfd2785421eb073851fab2fc8b5bb4dacf2d0e89edb5be37e. How it applies: The decision date. 3. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: results\[0\].decision\_code. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: bf1f58d99ebe7cfcfd2785421eb073851fab2fc8b5bb4dacf2d0e89edb5be37e. How it applies: The decision code DENG. 4. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: results\[0\].device\_name. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: bf1f58d99ebe7cfcfd2785421eb073851fab2fc8b5bb4dacf2d0e89edb5be37e. How it applies: The device name as FDA records it. 5. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: results\[0\].product\_code. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: bf1f58d99ebe7cfcfd2785421eb073851fab2fc8b5bb4dacf2d0e89edb5be37e. How it applies: The product code. 6. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: Decision field. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: 57eea5005cef94c47b8914a4b55b54d12d81c152b8b4be04944b3a04add929cd. How it applies: The accessdata page states the decision as granted. 7. Supports: FDA De Novo request DEN220027, B·R·A·H·M·S sFlt-1/ PlGF KRYPTOR Test System (Brahms GmbH, part of Thermo Fisher Scientific) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) endpoint returns the De Novo record too (meta.last\_updated 2026-09-28), with the decision date and the decision code DENG and a decision description of Unknown. The accessdata denovo.cfm page says granted. The decision summary PDF was fetched (fetch-log label mc-fda-denovo-summary-den220027.pdf) and has no snapshot record, because its text layer is scanned and has character errors in trade names.) Locator: Classification fields. Retrieved 2026-10-11T19:11:37Z. Source state: Current. Snapshot hash: 57eea5005cef94c47b8914a4b55b54d12d81c152b8b4be04944b3a04add929cd. How it applies: The product code on the De Novo page. 8. Supports: 21 CFR 862.1602, Prognostic test for development or progression of preeclampsia (eCFR) (Regulator, edition eCFR versioner API text for the version dated 2026-10-01, as fetched on 2026-10-11. The first request (mc-ecfr-862-1602-nocompression.xml) returned HTTP 406 because it did not accept compression, and a request for the version dated 2026-10-09 (mc-ecfr-862-1602-retry.xml) returned HTTP 404.) Locator: Section heading. Retrieved 2026-10-11T19:14:47Z. Source state: Current. Snapshot hash: 40d9dddc624d5ae8c365a5a4d95a64b105d43a43041133af9144573c4af440e1. How it applies: The regulation number and its name. 9. Supports: 21 CFR 862.1602, Prognostic test for development or progression of preeclampsia (eCFR) (Regulator, edition eCFR versioner API text for the version dated 2026-10-01, as fetched on 2026-10-11. The first request (mc-ecfr-862-1602-nocompression.xml) returned HTTP 406 because it did not accept compression, and a request for the version dated 2026-10-09 (mc-ecfr-862-1602-retry.xml) returned HTTP 404.) Locator: (b) Classification, sentence 1. Retrieved 2026-10-11T19:14:47Z. Source state: Current. Snapshot hash: 40d9dddc624d5ae8c365a5a4d95a64b105d43a43041133af9144573c4af440e1. How it applies: Class II with special controls. 10. Supports: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: 510(k) Summary, submitter table, predicate devices row. Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: K241453 names the KRYPTOR system, DEN220027, as its predicate. 11. Background: PLGF-based testing to help diagnose suspected preterm pre-eclampsia (NICE HealthTech guidance HTG630, formerly diagnostics guidance DG49) (Guideline, edition Three pages as shown on 2026-10-11: the Overview, chapter 1 Recommendations and chapter 2 The diagnostic tests. The page header gives the reference number and the publication date. The Overview says diagnostics guidance 49 was migrated to HealthTech guidance 630 with its recommendations and content unchanged. The old DG49 address was fetched too (fetch-log label mc-nice-htg630-dg49.html) and says the guidance itself has not changed; it has no snapshot record.) Locator: 1.6, sentence 1. Retrieved 2026-10-11T19:10:54Z. Source state: Current. Snapshot hash: a398cf1b5677008d605646e1ca3792bb0a883ee77eec80f55a16e0f02251d7be. How it applies: NICE does not recommend the BRAHMS ratio test for routine NHS use. 12. Supports: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: 510(k) Summary, Table 1 (summary pp. 5 to 6, PDF pp. 9 to 10), predicate column, intended use cell. Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: The KRYPTOR system as printed in Roche's K241453 comparison table: automated TRACE immunofluorescent assays. 13. Supports: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: 510(k) Summary, Table 1 (summary pp. 5 to 6, PDF pp. 9 to 10), predicate column, intended use cell, hospitalized population (text order without -layout). Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: The KRYPTOR indication population: women hospitalized for hypertensive disorders of pregnancy. 14. Supports: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: 510(k) Summary, Table 1 (summary pp. 5 to 6, PDF pp. 9 to 10), predicate column, end of intended use cell (text order without -layout). Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: The KRYPTOR time window, "within 2 weeks of presentation", and its reference to the American College of Obstetricians and Gynecologists definition. 15. Supports: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: 510(k) Summary, Table 1 (summary pp. 5 to 6, PDF pp. 9 to 10), predicate column, intended use cell, PlGF assay sample matrix (text order without -layout). Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: The KRYPTOR PlGF assay accepts human serum and plasma (K2 EDTA). 16. Background: FDA 510(k) premarket notification K241453, Elecsys sFlt-1 and Elecsys PlGF (Roche Diagnostics) (Regulator, edition Two retrievals on 2026-10-11. The openFDA device 510(k) JSON record (meta.last\_updated 2026-09-28) gives the decision date, product code and decision. The 510(k) summary PDF (27 pages) holds FDA's clearance letter, the Indications for Use form and Roche's own 510(k) Summary. The accessdata pmn.cfm page was fetched too (fetch-log label mc-fda-pmn-k241453.html) and has no snapshot record. The openFDA classification record for product code QWH was fetched as well (mc-openfda-class-qwh.json) and is not used, because the eCFR text of 21 CFR 862.1602 is the primary source for the device type.) Locator: Indications for Use form, second sentence, third part. Retrieved 2026-10-11T19:11:38Z. Source state: Current. Snapshot hash: edc99e5f8d778ceb857c5c649899e2ef4469ca6b919ee6e47f4e9a07b9662f00. How it applies: The Elecsys wording for the outcome window, for comparison with the KRYPTOR wording. ## Connected pages - Reports the sFlt-1/PlGF ratio: sFlt-1/PlGF ratio (`maternal:sflt1-plgf-ratio`) - Related to: PlGF-based testing for suspected preterm pre-eclampsia (`maternal:plgf-based-testing`) - Used by: Elecsys sFlt-1 and Elecsys PlGF (Roche) (`maternal:elecsys-sflt1-plgf`) ## Provenance Content hash: 9e664e57af2c5389bcb1278ce1d94aec06053e2ce57de5918463aa31422810a2 Last substantive edit: 2026-10-13 Evidence last checked: 2026-10-12