Rules for use of SIprefixes in laboratory medicine
 Overview
 SI prefix table (modified)
 Various expressions of SI units
 Unit one or SI factor as measurement units
Definition  SI prefixes are a set of multiples and submulitples within the SI system 

Purpose of the use of SIprefixes 
To prevent communication errors due to several expressions of the same unit To ensure that the numerical values in laboratory results are human readable and understandable 
Principles 

Rules 

Reference 

Factor (SI factor)  Term (SI prefix name)  Symbol (SI prefix) 

10^{–30}  quecto  q 
10^{–27}  ronto  r 
10^{–24}  yocto  y 
10^{–21}  zepto  z 
10^{–18}  atto  a 
10^{–15}  femto  f 
10^{–12}  pico  p 
10^{–9}  nano  n 
10^{–6}  micro  µ 
10^{–3}  milli  m 
10^{3}  kilo  K 
10^{6}  mega  M 
10^{9}  giga  G 
10^{12}  tera  T 
10^{15}  peta  P 
10^{18}  exa  E 
10^{21}  zetta  Z 
10^{24}  yotta  Y 
10^{27}  ronna  R 
10^{30}  quetta  Q 
Note: SI prefixes (deci (d), centi (c), deca (Da), and hecto (H) are not allowed or displayed due to a less distance than 1000 between the next SI prefixes.
Background 
A measurement unit can be expressed with several combinations of SI prefix and SI factors that may placed in the denominator and numerator. To avoid confusion and misunderstanding with various different expressions of the same unit, a preferred unit symbol should be used. 

Examples 
Examples of various unit symbols for the same measurement unit Note: The last unit symbol, gram per decilitre, is not recommended to use because the distance between g/dL and g/L is only a factor 10. 
Reference 

Principle  Kindsofquantity of dimension one (e.g. mass fraction, substance ratio, number concentration) may have “one” or SI factors as corresponding measurement units. 

Background 
There are several combinations of unit symbols for SI factors. To avoid confusion and misunderstanding with several unit symbols for the same measurement unit, the measurement unit equation undergoes a linear algebraic reduction. The linear algebraic reduction will change the unit equation into a simpler form. Note 1: When SI factors are used as measurement units, it is in particular important to display the kindofquantity along the measurement unit, to understand the measurement unit Note 2: The same SI factor may be used as measurement unit for different kindsofquantity 
Examples 
Example 1 Linear algebraic reduction of a measurement unit equation into a SI factor that is the preferred unit symbol. Example 2 The same SI factor can be used as corresponding measurement unit for other kindsofquantity.

Reference 
