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Reference Range

Min : 102
Max : 496

Min : 86
Max : 324

Test Usage

Prolactin is secreted by the anterior pituitary gland and induces lactation. Normally, prolactin is secreted in a pulsatile, sleep dependent rhythm with highest levels occurring during sleep and lowest levels occurring a few hours after waking. Prolactin secretion by the pituitary gland is under tonic inhibition from the hypothalamus via dopamine. Any lesion of the pituitary stalk prevents tonic inhibition and allows prolactin levels to rise. Prolactin concentrations normally rise with illness and physical stress. If pharmacologic doses of thyrotrophin releasing hormone (TRH) are administered, prolactin concentrations can increase.

Suggested guidance for elevated prolactin of unknown cause:

For prolactin results 700 – 2000 mIU/L: 

Moderately elevated prolactin. Consider causes including renal insufficiency; hypothyroidism; medications such as OCP and some antipsychotics, antidepressants or antiemetics; PCOS; recent or ongoing stressful events; excessive exercise; breastfeeding. Where applicable rule out pregnancy. The laboratory has ruled out a known spurious cause of hyperprolactinaemia called “macroprolactin”. 


If no clear cause is identified, a repeat measurement of prolactin is suggested. The sample should be taken at least 1 hour after waking, where applicable at day 1 to 4 of the follicular phase and if possible after any stressful circumstance/event has resolved. If prolactin remains elevated at a similar or higher level consider discussing with endocrinology. 


For prolactin results >2000 mIU/L: 

Marked elevation of prolactin. Rule out pregnancy, breastfeeding or any drugs known to cause substantial elevation of prolactin e.g. some antipsychotics or antidepressants. The laboratory has ruled out a known spurious cause of hyperprolactinaemia called “macroprolactin”. 

If the above are ruled out, discussion with endocrinology is suggested. 

Turnaround time

1 day


Local test

Can be added on to an existing request up to 4 days following sample receipt

Specimen Labelling Procedure
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