C-Peptide

Endocrine

Normal Reference Ranges

Adult

0.5 - 2.0 ng/mL

Pediatric

0.5 - 2.0 ng/mL

Clinical Significance

Cleaved from proinsulin. Helps differentiate endogenous insulin production (Insulinoma) from exogenous insulin administration (surreptitious injection).

Causes of High

  • Insulinoma
  • Type 2 Diabetes (early stage insulin resistance)
  • Renal failure

Causes of Low

  • Type 1 Diabetes (beta cell destruction)
  • Exogenous insulin administration (factitious hypoglycemia)