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PTD - 248

Test Directory -  IGF-1
Please note change of units and reference ranges from 11.3.2013


Insulin-like Growth Factor 1, 

Clinical Indications

Screening for acromegaly. An elevated IGF-1 in a patient with the appropriate clinical picture is diagnostic. Occasionally acromegalics may have a normal IGF-1 level at diagnosis so a growth hormone suppression test remains the definitive diagnostic test.
Follow up of treatment for acromegaly. IGF-1 should be measured annually along with growth hormone. Elevated IGF-1 with normal growth hormone levels may indicate a need for further lowering growth hormone levels.

Request Form

Combined Pathology Blood form (Yellow/Black)


Referred test: Analysed by the SAS Peptide Hormone Laboratory, Royal Surrey County Hosptial, if specific criteria met.

Specific Criteria

Requested by Consultant Endocrinologists or if agreed with Consultant Biochemist.

Patient Preparation None required.

Turnaround Time

2 weeks




2 ml


Red top (serum) tube is preferred. Yellow top (SST) or green top (li-heparin)tubes can be used but must be separated 'promptly' (within 4 hours of collection).

For paediatrics a brown top (serum tube) is preferred. An orange top (lithium heparin) sample can also be used.


Samples must be transported to laboratory within 4 hours of collection.

Causes for Rejection

Not meeting specific criteria for analysis. Delay in sample reaching laboratory. Sample collected into tube containing gel.

Reference Range Age Range Reference Range
Up to 6 years 4 - 20 nmol/L
6 - 9 years  7 - 40 nmol/L
  10 years 12 - 50 nmol/L  
  11 years 17 - 60 nmol/L  
  12 years 20 - 85 nmol/L  
  13 years 23 - 90 nmol/L  
  14 - 16 years 30 - 90 nmol/L  
17 - 20 years 23 - 70 nmol/L
  21 - 40 years 13 - 50 nmol/L  
  41 - 60 years 9 - 40 nmol/L  
  > 60 years 6 - 36 nmol/L  

Lab. Handling

Processing: Centrifuge and aliquot immediately into 2 tubes and freeze at     -20C in separating freezer (CB40), active frozen rack 110. This test can be added on retrospectively as long as the sample was separated within 4 hours of collection and it is frozen on the day of collection.

Referral: IGF1 and send or NOIGF and save in separating freezer (CB40) at
-20C, saved frozen rack.


Version 1.0 / November 2014                                                                                                 Approved by: Consultant Biochemist