Dimension table: lab items

Hospital level table


d_labitems contains definitions for all itemid associated with lab measurements in the MIMIC database. All data in LABEVENTS link to the d_labitems table. Each unique (fluid, category, label) tuple in the hospital database was assigned an itemid in this table, and the use of this itemid facilitates efficient storage and querying of the data.

Laboratory data contains information collected and recorded in the hospital laboratory database. This includes measurements made in wards within the hospital and clinics outside the hospital. Most concepts in this table have been mapped to LOINC codes, an openly available ontology which facilitates interoperability.

  • LABEVENTS on itemid

Important considerations

  • Many of the LOINC codes were assigned during a project to standardize the ontology of lab measurements in the MIMIC database. Consequently, the codes were assigned post-hoc, may not be perfect, and may not be present for every lab measurement. We welcome improvements to the present codes or assignment of LOINC codes to unmapped data elements from the community.

Table columns

Name Postgres data type
itemid INTEGER
label VARCHAR(50)
fluid VARCHAR(50)
category VARCHAR(50)
loinc_code VARCHAR(50)

Detailed Description


A unique identifier for a laboratory concept. itemid is unique to each row, and can be used to identify data in LABEVENTS associated with a specific concept.


The label column describes the concept which is represented by the itemid.


fluid describes the substance on which the measurement was made. For example, chemistry measurements are frequently performed on blood, which is listed in this column as ‘BLOOD’. Many of these measurements are also acquirable on other fluids, such as urine, and this column differentiates these distinct concepts.


category provides higher level information as to the type of measurement. For example, a category of ‘ABG’ indicates that the measurement is an arterial blood gas.


loinc_code contains the LOINC code associated with the given itemid. LOINC is an ontology which originally specified laboratory measurements but has since expanded to cover a wide range of clinically relevant concepts. LOINC openly provide a table which contains a large amount of detail about each LOINC code. This table is freely available online.

Last modified August 14, 2020: update website to use docsy (adc506c)