Is there a word for a piece of medical data about the body

"Reading," "readout/read-out," "measurement," "display," "scan," or "indication" could work (depending on the type of data and machine).

Reading:

A figure or amount shown by a meter or other measuring instrument. [Lexico]

Readout/read-out:

A visual record or display of the output from a computer or scientific instrument. [Lexico]

Measurement:

The size, length, or amount of something, as established by measuring. [Lexico]

Display:

The data shown on a computer screen or other device. [Lexico]

Scan:

A medical examination using a scanner. [Lexico]

Indication:

A reading given by a gauge or meter. [Lexico]

One word I haven't seen anyone use is "vitals," but that typically has a connotation of essential, immediate readings, and it's mostly used by medical professionals.

Scans and tests (x-rays, blood tests, brain scans, ultrasounds, etc.) would not fall under the term vital, as they are not immediate, time-sensitive information about the body.

The vital signs (body temperature, pulse rate, respiration rate), along with blood pressure and oxygen saturation would be considered vitals, as they can easily indicate when someone needs immediate attention. I think EKG would also typically be included if someone using the word was speaking more broadly (but generally only in hospitals, as your average doctor doesn't take EKGs unless something is suspected to be wrong).

Diagnostics or results could be used