Immunoreactive insulin-like growth factor II in urine

Area of Science:

• Endocrinology
• Nephrology
• Biochemistry

Background:

• Insulin-like growth factors (IGFs) play crucial roles in cellular processes.
• Understanding IGFs and their binding proteins in urine is important for metabolic and kidney health.
• Previous research has limited data on urinary IGF-II and IGF binding protein-1 concentrations.

Purpose of the Study:

• To identify and quantify insulin-like growth factor II (IGF-II) and insulin-like growth factor binding protein-1 (IGFBP-1) in the urine of healthy adults.
• To compare urinary IGF-II levels with IGF-I.
• To investigate the presence of pro-IGF-II and binding protein interactions in urine.

Main Methods:

• Urine samples from 23 healthy subjects (aged 17-76) were analyzed.
• IGF-II was measured using gel chromatography at low pH, with comparison to IGF-I.
• IGFBP-1 was quantified in dialyzed urine samples.

Main Results:

• Urinary IGF-II concentrations (mean ± SEM: 717 ± 69 ng/mmol creatinine) were substantially higher than IGF-I (110 ± 5 ng/mmol creatinine).
• Chromatographic analysis suggested the potential presence of pro-IGF-II.
• Mean IGFBP-1 concentration was 414 ± 83 ng/mmol creatinine, with evidence of IGFs being bound to proteins in urine.

Conclusions:

• Urinary IGF-II is present at significantly higher concentrations than IGF-I in healthy individuals.
• The findings indicate that IGFs in urine are partially bound to binding proteins.
• Further research is warranted to explore the physiological significance of urinary IGF-II and IGFBP-1.