Proinsulin

Email

Send Email

Recipient(s) will receive an email with a link to 'Proinsulin' and will have access to the topic for 7 days.

Subject: Proinsulin

(Optional message may have a maximum of 1000 characters.)

×


Definition

  • Enzymatic process forms insulin in pancreatic secretory granules of beta cells. Proinsulin level is normally ≤20% of total insulin. Proinsulin has low biologic activity (10% insulin potency) and is the major storage form of insulin. Proinsulin is included in the immunoassay of total insulin, and separation requires special technique.

  • Normal range: 2.0–2.6 pmol/L.

Use

  • Proinsulin: Insulin ratio is used as an indirect marker of beta cell function.

Interpretation

  • High proinsulin levels associated with benign or malignant beta cell tumors of the pancreas and endocrine pancreatic tumors associated with MEN-1.

  • Elevated levels are positive risk factor for the development of NIDDM.

  • Elevated levels in patients with chronic renal failure, cirrhosis, and hyperthyroidism.

  • Proinsulin >30% of serum insulin after overnight fast suggests insulinoma.

  • Proinsulin is increased in factitious hypoglycemia due to sulfonylurea.

  • Proinsulin is increased in familial hyperproinsulinemia—heterozygous mutation affecting cleavage of proinsulin leading to secretion of excess amounts of proinsulin.

  • Type 2 DM.

Limitations

  • Proinsulin may also be increased in renal disease.

  • Elevation of proinsulin: insulin ratio correlates with a decreased acute illness response to glucose in patients with type 2 DM.

 
×