What it means
In lab reports, SI units are the International System of Units, the metric units most of the world uses (for example, glucose in mmol/L rather than mg/dL). In mental health notes, SI means suicidal ideation, thoughts of ending one's life. In musculoskeletal notes, the SI joint is the sacroiliac joint, where the spine meets the pelvis.
For the nurse
Read SI in context. A note of SI in a mental health assessment calls for a direct safety assessment of the client, not a guess at the meaning.
Related terms
suicidal ideation
Thinking about, considering or planning suicide.
sacr/o
A word root that means the sacrum, the triangle-shaped bone at the base of the spine.