Insulin, Serum

Specimen requirement Adult patient:

  Clotted blood tube (Clot activator tube) (in ice bath)

Minimum blood volume: 6 mL
Paediatric patient:

Paediatric clotted blood tube (in ice bath)

Number of vials: 2

Minimum blood volume: 1.6 mL
Authorisation code required Yes
24 Hr available service No
Precaution

Send in ice immediately to the laboratory with concurrent plasma glucose.

 

Haemolysis can lead to spuriously low value.

 

The presence of circulating anti-insulin antibodies and certain insulin analogues may interfere the insulin result.

Method Immunoassay
Reference interval

2.6 - 24.9 mIU/L (Fasting)

(Source: from manufacturer's kit insert)

Footnote:
Insulin level depends on factors such as pancreatic reserve, plasma glucose, state of fasting, etc. Please interpret insulin with concurrent glucose result.
Clinical indication

Investigation of fasting hypoglycaemia and insulin resistant states
Result interpretation

During a hypoglycaemia episode (plasma glucose ≤ 3.0 mmol/L), non-suppressed insulin suggests insulin-mediated causes. Serum C-peptide would be added if serum insulin is ≥ 3 mIU/L in adults, or serum insulin is detectable (≥ 1 mIU/L) in paediatric patients.

Patients with insulin resistance might have high fasting serum insulin.
Measurement of uncertainty See table.
Frequency of measurement 1 - 2 weeks