LB and LC Domains for SI and Conventional Units in FDA Clinical Study Data
FDA’s June 2026 guide distinguishes LB and custom LC laboratory representations for SI versus conventional units in clinical study submissions.
ReviewedEvidence1 sourceSectionWriting & Style
Quick answer
For clinical studies, FDA’s June 2026 guide calls for separate laboratory representations for SI and conventional units: LB carries SI results/units, while a custom LC domain structured like LB carries conventional-unit results when applicable.
Key details
Core IssueFDA’s June 2026 guide distinguishes LB and custom LC laboratory representations for SI versus conventional units in clinical study submissions.
Registerscholarly, professional, or research/report writing
Important caveats
Scope Boundary
This is current FDA technical-conformance guidance for electronic study-data submissions; recheck the current FDA guide, supported standards, Data Standards Catalog, and eCTD specifications before relying on version-sensitive requirements.
Further guidance
Content
For clinical laboratory data, use LB for SI-unit results and the identically structured custom LC domain for conventional-unit results as described by the guide, keeping corresponding observations aligned.
Purpose
Let reviewers work with both unit systems while preserving a predictable relationship between the standard LB data and the conventional-unit LC representation.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
FDA’s June 2026 conformance guide says a custom domain should be used only after confirming the data do not fit an existing domain, with implementation described in the clinical Study Data Reviewer’s Guide.
FDA’s June 2026 guide describes the DD (Death Details) domain for supplemental information collected when a death occurs and expects consistency with relevant AE-domain death variables.
FDA’s June 2026 conformance guide says screen failures, when provided, should be represented as a DM record with specified planned/actual arm fields left blank.
FDA’s June 2026 guide gives DS-domain handling for multiple disposition events, including use of EPOCH or DSSCAT and a specific final-record convention for death.
FDA’s June 2026 guide explicitly calls for the DV domain in submissions containing protocol-deviation data and identifies review-oriented variables beyond CDISC-required fields.
ICH E3 section 11.4.2.3 calls for interim analyses and data-monitoring activity relevant to the study results to be identified, including their timing, role, and implications for interpretation. Keep this CSR results/reporting scope separate from a general methods-only discussion of stopping rules or trial-governance policy.
