What does this LOINC code represent?

This LOINC code identifies a lab observation, measurement, question, or clinical concept in a standardized format.

Is this enough to understand my test result?

No. The code identifies the test or observation, but the interpretation depends on the actual result, reference range, and clinical context.

LOINC

LOINC Code 64634-9: How old were you when your menstrual periods began [PhenX]

Name: LOINC Code 64634-9: How old were you when your menstrual periods began [PhenX]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:44.549Z

64634-9 is a LOINC code used to identify How old were you when your menstrual periods began [PhenX] 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 How old were you when your menstrual periods began. It is commonly used with the system or sample type ^Patient.

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 How old were you when your menstrual periods began. It is commonly used with the system or sample type ^Patient.

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: TRIAL
Method: PhenX

What it does not mean

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

Key facts

How old were you when your menstrual periods began [PhenX]
How old were you when your menstrual periods began
Menstrual period began first age; Point in time; QNT; Quan; Quant; Quantitative; Random

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

How old were you when your menstrual periods began [PhenX]Menstrual period began first age PhenXHow old were you when your menstrual periods beganPHENXTimePt^Patient

Frequently asked questions

Code details

Code64634-9

SystemLOINC

Display nameHow old were you when your menstrual periods began [PhenX]

DescriptionHow old were you when your menstrual periods began

Short nameMenstrual period began first age PhenX

ComponentHow old were you when your menstrual periods began

PropertyTime

TimingPt

System (specimen)^Patient

ScaleQn

MethodPhenX

ClassPHENX

Example unitsyears

StatusTRIAL

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.36

Last changed2.65

Part names

How old were you when your menstrual periods beganTimePt^PatientQnPhenXTime (e.g. seconds)Point in time (spot)

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.