Insulin
Biochemistry Overview / Directory
Purpose of the test
Insulin is synthesized from its precursors, preproinsulin and proinsulin in the beta cells of the islets of Langerhans and serves as a regulator for the storage and production of carbohydrates. Secretion of insulin is stimulated by an increased glucose concentration in circulation. This leads to higher insulin concentrations and more rapid tissue assimilation of glucose followed by a decline in insulin concentrations as the glucose concentration reduces.
The relationship between glucose and insulin must be strictly balanced. When this balance is disturbed, insulin is either under- or over-excreted.
Insulin concentrations are severely reduced in insulin-dependent diabetes mellitus (IDDM) and hypopituitarism. Insulin concentrations are raised in non-insulin dependent diabetes mellitus (NIDDM), obesity, insulinoma and certain endocrine conditions such as Cushing syndrome and acromegaly.
The predominant clinical indications for insulin measurement include:
a) the diagnosis of insulinoma and other causes of hypoglycaemia,
b) the diagnosis and study of cases of insulin resistance,
c) the differentiation between insulin-and non-insulin-dependent diabetes,
d) characterisation and follow-up of states of glucose intolerance,
e) the determination of beta-cell reserve during glucose tolerance test or after a carbohydrate rich meal, as a guide for initiating insulin therapy.
Reference Range
5-30 mU/L for a fasting sample
Sample Requirements
Serum from a plain vacutainer (250 µL). Even slightly haemolysed samples are unsuitable for analysis
Storage and Transport
Send frozen on dry ice.
Turnaround Time
2 weeks
Price
Price available on application - please contact adrian.turner@kch.nhs.uk. Discounts could be available for significant workloads.
Contacts
Miss Rachel Langworthy
T 020 3299 4130
E rachel.langworthy@kch.nhs.uk
Dr Roy Sherwood
T 020 3299 3726
