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Short- and medium-term pre-analytical stability of human serum insulin-like growth factor-1.

Author(s): Louw JC, George JA, Khoza SP, Currin S

Publication: Clin Chem Lab Med, 2025, Vol. , Page

PubMed ID: 41167200 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared insulin like growth factor -1 (IGF-1) levels in serum that was stored at −20°C, 4°C, 20–25°C and 30°C for up to 672 h and in serum obtained after an 8 or 24 h centrifugation delay followed by storage at either 4°C or 20–25°C for up to 672 h. Blood was collected from 10 healthy volunteers (median age: 32 years) into serum separator tubes. Specimens from 4 volunteers were centrifuged (3,500 rpm for 10 min) after 30 min and then matched serum aliquots were stored at -20°C, 4°C, 20-25°C and 30°C for 24, 72, 168 and 672 h.  Specimens from 2 volunteers experienced a pre-centrifugation delay of 8 h at 4°C or 20-25°C, were centrifuged (3,500 rpm for 10 min), and then serum aliquots were stored again at 4°C or 20-25°C for a total duration (including pre-centrifugation storage) of 8 (no additional storage), 24, 72, 168 and 672 h and compared to immediately centrifuged and analyzed specimens. Specimens from the final 2 volunteers experienced a pre-centrifugation delay of 24 h (at 4°C or 20-25°C), were centrifuged (3,500 rpm for 10 min), and then serum aliquots were again stored at 4°C or  20-25°C for a total duration (including pre-centrifugation storage) of 24 (no additional storage), 48, 72, 168 and 672 h and compared to immediately centrifuged and analyzed specimens. IGF-1 levels were quantified using a DiaSorin LIAISON XL.  The percentage deviation from baseline was considered significant if it was greater than the biological deviation of 10.7%. 

   Summary of Findings:

   Among specimens that were centrifuged immediately, IGF-1 levels were statistically higher compared to specimens analyzed immediately when stored at 20-25°C or 30°C for 24, 72 or 168 h (P<0.01, all), or stored at -20°C for 168 h (P=0.01), and statistically lower when stored at 4°C, 20-25°C or 30°C for 672 h (P<0.01, all). However, the percentage deviation in immediately centrifuged specimens only exceeded the biological deviation of 10.7% when they were stored at 4°C for 672 h (-33.1%), at 20-25°C for 168 h (12.9%) or 672 h (-27.3%), or 30°C for 672 h (-38.3%). Specimens subjected to an 8 h centrifugation delay had significantly higher IGF-1 levels compared to immediately analyzed specimens (no centrifugation delay) when stored at 4°C or 20-25°C for 8 h (no additional storage, P<0.01, both), 20-25°C for 24, 72 or 168 h (P<0.01, all) and lower IGF-1 when stored at either 4°C or 20-25°C for 672 h (P<0.01); however, the percentage deviation was clinically significant only when specimens were stored at 4°C or 20-25°C for 672 h (-28.3% and -27.5%, respectively). Specimens centrifuged after a 24 h delay at 4°C had higher levels of IGF-1 compared to immediately analyzed specimens when stored at 4°C for a total of 24 h (no additional storage), or 48 h (24 h post-centrifugation) (P<0.01, both) and lower levels when stored for a total of 672 h (P<0.01).  Specimens centrifuged after a 24 h delay at 20-25°C had higher levels of IGF-1 compared to immediately analyzed specimens when stored for a total of 24 (no additional storage), 48, 72, or 168 h (P<0.01, all) and lower levels of IGF-1 when stored at for 672 h (P<0.01). However, clinical significance among specimens subjected to a 24-h centrifugation delay was limited to the elevated IGF-1 levels in specimens stored at 20-25°C for 168 h (12.4%) and the reduced levels in specimens stored for 672 h at either 4°C or 20-25°C (-24% and 30.2%, respectively). The authors conclude that IGF-1 is stable for a combined centrifugation delay and storage of at least 72 h, regardless of storage temperature, at 4°C for up to 168 h regardless of the centrifugation delay, and at -20°C for at least 672 h (centrifugation delays not investigated).

   Biospecimens

   • Bodily Fluid - Serum
   • Bodily Fluid - Blood

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Peptide	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Aliquots and Components	Centrifugation	Centrifuged
   Storage	Storage temperature	-20°C 4°C 20-25°C 30°C
   Storage	Storage duration	0 h 24 h 72 h 168 h 672 h 8 h before centrifugation 24 h including 8 h before centrifugation 72 h including 8 h before centrifugation 168 h including 8 h before centrifugation 672 h including 8 h before centrifugation 24 h before centrifugation 48 h including 24 h before centrifugation 72 h including 24 h before centrifugation 168 h including 24 h before centrifugation 672 h including 24 h before centrifugation

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