LOINCActiveObservation

LOINC Code 51631-0: Platelet distribution width (Bld) [Ratio]

51631-0 is a LOINC code used to identify Platelet distribution width (Bld) [Ratio] in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Platelet distribution width. It is commonly used with the system or sample type Bld.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Platelet distribution width. It is commonly used with the system or sample type Bld.

When is it used?

  • Used in lab systems, EHRs, and clinical data exchange.
  • May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
  • Status: ACTIVE
  • Order vs observation: Observation

What it does not mean

  • The code identifies the observation or test, not the actual result.

Key facts

  • Platelet distribution width [Ratio] in Blood
  • Platelet distribution width
  • Blood; HEMATOLOGY/CELL COUNTS; PDW; Pl; Platelets; Platelt; Plt; Point in time; QNT; Quan; Quant; Quantitative; Random; Ratios; Rto; Thrombocyte; Thrombocytes; WB; Whole blood

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Platelet distribution width (Bld) [Ratio]Platelet distribution width [Ratio] in BloodPDW Bld-RtoPlatelet distribution widthHEM/BCPlatelet distribution width, BloodRatio

Frequently asked questions

Code details

Code51631-0
SystemLOINC
Display namePlatelet distribution width (Bld) [Ratio]
DescriptionPlatelet distribution width
Short namePDW Bld-Rto
ComponentPlatelet distribution width
PropertyRatio
TimingPt
System (specimen)Bld
ScaleQn
ClassHEM/BC
Example units%
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.24
Last changed2.70

Consumer names

Platelet distribution width, Blood

Part names

Platelet distribution widthRatioPtBldQnPoint in time (spot)Blood

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

LOINC Code 51631-0 | HealthAssure