Lab Test

Proinsulin Level

Test Codes

MAYO: PINS, EPIC: LAB6138, SOFT: XPROI

Instructions

  • The patient must be fasting 8 hours prior to specimen collection.
  • Pre-chill the specimen tube in a freezer for at least 10 minutes prior to collection.

Specimen Collection Criteria

Collect: One pre-chilled Lavender-top EDTA tube.

  • Collect specimen on ice.
  • Send specimen for processing immediately after collection.

Physician Office/Draw Specimen Preparation

Centrifuge to separate plasma from cells. Immediately transfer plasma to a plastic transport tube and freeze (-20°C/-4°F or below).

Preparation for Courier Transport

Transport: 0.5 mL plasma, frozen (-20°C/-4°F or below). (Minimum: 0.25 mL)

Rejection Criteria

Grossly hemolyzed specimens.

Specimens not collected and processed as indicated.

Inpatient Specimen Preparation

Place specimen on wet ice and transport to the Laboratory immediately for processing.

In-Lab Processing

Centrifuge to separate plasma from cells. Immediately transfer plasma to a plastic transport tube and freeze (-20°C/-4°F or below).

Transport: 0.5 mL plasma, frozen (-20°C/-4°F or below). (Minimum: 0.25 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Mayo Medical Laboratories, Rochester, MN.

Performed

Tuesday, Friday.
Results available in 3-7 days.

Reference Range

3.6-22 pmol/L.

Test Methodology

Electrochemiluminescent Assay.

Interpretation

Diagnosis of Insulinomia after fasting:

  • 85% of patients with insulinomia have increased proinsulin values.
  • All normal patients have proinsulin values below 20 pmol/L.

Medications affecting insulin production or secretion will also affect Proinsulin.

Clinical Utility

Proinsulin is secreted by the pancreas and is rapidly digested to insulin and C-peptide. In normal subjects, proinsulin comprises 5-10% of the total insulin. In subjects with ectopic insulin production, insulinomas, and islet cell tumors proinsulin averages about 40% of the total insulin concentration. Chronic renal failure patients also exhibit elevated levels of proinsulin, but circulating insulin levels are also increased correspondingly.

CPT Codes

84206

Contacts

Last Updated

4/1/2020

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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.