Arbitrary number (arb.num.)
Abbreviation 
Arb.num.  

Definition in words 
Note 1: This concept has two definitions. Note 2: The reference system is defined by the laboratory. 

Definition by equation 
Note: k_{procedure} is a constant defined by the measurement procedure (there is an approximately proportionality to a kindofquantity from the International System of Quantities) 

Result type 
Ordinal scale 


Rational scale 



Unit 
International unit (IU) or procedure defined unit (p.d.u.) (nonSI units)  
Special rule(s) in the NPU syntax 
“Procedure” is stated in the specification to the kindofproperty in the NPU definition. “Procedure” indicates that the measurement procedure must be stated somewhere else than the NPU code and there may be difficulties in comparing values for the same NPU code. If the ratio scale is attributed to the NPU definition, the unit can be nonSI unit. If the unit is an International Unit (IU), an international certified reference material (e.g. WHO reference material) is specified in the specification to the kindofproperty. If there exist no international certified reference material, the laboratory can specify the unit at the placeholder, procedure defined unit. If ordinal scale is attributed, no unit is stated. 

Reference 

Laboratory field 
Examples 


Allegology 
Example 1 (ordinal)  
Generic abbreviated form  NPU02480 Ercs(B)—Immunoglobulin E; arb.num.(proc.) = ?  
Full form with a result  NPU02480 Erythrocytes(Blood)—Immunoglobulin E; arbitrary number(procedure) = high  
Abbreviated form with a result  NPU02480 Ercs(B)—Immunoglobulin E; arb.num.(proc.) = high  
Written expression  The arbitrary number of Immunoglobulin E of Erythrocytes in Mr Smith’s blood is [high] compared with the arbitrary number of Immunoglobulin E of Erythrocytes in a reference system. The measurement is performed according to a procedure defined by the given laboratory.  
Notes 


Clinical Chemistry 
Example 2 (ratio)  
Generic abbreviated form  NPU18636 U—Ercs; arb.num.(proc.) = ? (p.d.u.)  
Full form with a result  NPU18636 Urine—Erythrocytes; arbitrary number(procedure) = 70 arbitrary unit  
Abbreviated form with a result  NPU18636 U—Ercs; arb.num.(proc.) = 70 arbitrary unit  
Written expression  The arbitrary number of Erythrocytes in Mr Smith’s urine is [70] arbitrary unit. The measurement is performed according to a procedure defined by the given laboratory.  
Equation  
Notes  “Arbitrary unit” was chosen by a local laboratory as a proprietary measurement unit and not an accepted international unit  
Example 3 (ordinal)  
Generic abbreviated form  NPU04063 Lkcs(B)—Aldosterone receptor; arb.num.(proc.) = ?  
Full form with a result  NPU04063 Leukocytes(Blood)—Aldosterone receptor; arbitrary numbers(procedure) = 2  
Abbreviated form with a result  NPU04063 Lkcs(B)—Aldosterone receptor; arb.num.(proc.) = 2  
Written expression  The arbitrary number of Aldosterone receptor of Leukocytes in Mr Smith’s blood is [2] compared with the arbitrary number of Aldosterone receptor of Leukocytes in a reference system. The measurement is performed according to a procedure defined by the given laboratory.  
Notes 


Clinical Immunology and Blood Bank 
Example 4 (ordinal)  
Generic abbreviated form  NPU20206 Ercs(B)—Erythrocyte BARC antigen; arb.num.(proc.) = ?  
Full form with a result  NPU20206 Erythrocytes(Blood)—Erythrocyte BARC antigen; arbitrary number(procedure) = high  
Abbreviated form with a result  NPU20206 Ercs(B)—Erythrocyte BARC antigen; arb.num.(proc.) = high  
Written expression  The arbitrary number of Erythrocyte BARC antigen of Erythrocytes in Mr Smith’s blood is [high] compared with the arbitrary number of Erythrocyte BARC antigen of Erythrocytes in a reference system. The measurement is performed according to a procedure defined by the given laboratory.  
Notes 


Clinical Microbiology

Example 5 (ratio)  
Generic abbreviated form  NPU18642 U—Trichomonas vaginalis; arb.num.(proc.) = ? (p.d.u.)  
Full form with a result  NPU18642 Urine—Trichomonas vaginalis; arbitrary number(procedure) = 0 arbitrary unit  
Abbreviated form with a result  NPU18642 U—Trichomonas vaginalis; arb.num.(proc.) = 0 arbitrary unit  
Written expression  The arbitrary number of Trichomonas vaginalis in Mrs Smith’s urine is [0] arbitrary unit.The measurement is performed according to a procedure defined by the given laboratory.  
Equation  
Notes  “Arbitrary unit” was chosen by a local laboratory as a proprietary measurement unit.and not an accepted international unit.  
Reproduction and Fertility 
Example 6 (ratio)


Generic abbreviated form  NPU18891 Sem—Spermatozoa; arb.num.(proc.) = 165 (p.d.u.)  
Full form with a result  NPU18891 Semen—Spermatozoa; arbitrary number(procedure) = 165 ELISA unit  
Abbreviated form with a result  NPU18891 Sem—Spermatozoa; arb.num.(proc.) = 165 Elisa unit  
Written expression  The arbitrary number of Spermatozoa in Mrs Smith’s semen is [165] ELISA unit. The measurement is performed according to a procedure defined by the given laboratory.  
Equation  
Notes  “ELISA unit” was chosen by a local laboratory as a proprietary measurement unit.and not an accepted international unit.  
Reference 
NPU database, https://www.ifcc.org/ifccscientificdivision/sdcommittees/cnpu/npusearch/ and http://www.labterm.dk/default.aspx 

Kindofproperty

Nominal kindofproperty

Kindofquantity

Ordinal kindofquantity

Arbitrary number


Unitary kindofquantity

Arbitrary number



Reference 

Date  Term  Note 

19960101  Arbitrary number  Term established 
NPU term identifier 
QU50151 