Specimen Collection

Requests for Macroprolactin - register PRML (3902)

Sample stability:

• 5 days at 20-25 ^o C
• 14 days at 2-8 ^o C
• 6 months at -20 ^o C

Macroprolactin

4.5 mL Adult PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

5 mL Adult Heparin Blood

4 mL Plain Blood

3.5 mL SST Blood

0.5 mL Paediatric Microsample Blood
Reference Intervals

Units: mIU/L

Reference ranges:

	lower	upper
M and F
0 - 30d	600	5000
31 - 60d	500	3200
2m - <9m	80	2000
9m - <5y	50	850
5y - <17y	40	600
17y and older
M	85	350
F	100	500

Conversion factors:

mIU/L = ng/mL x 21.2

mIU/L = ug/L x 21.2

Uncertainty of Measurement: 5%

Turnaround Time: Within 3 hours

Macroprolactin (MPRL) is performed once a week.

Assay Method

Principle: Sandwich type immunoassay with chemiluminescence detection

Assay: Roche Elecsys Prolactin II

Analyser: Cobas e801

Diagnostic Use and Interpretation

Prolactin measurements may be helpful in the investigation of galactorrhoea, amenorrhoea, infertility or hypogonadism. Mildly raised levels (up to 2 to 3 times the upper reference limit) are common and can be due to many causes.

Causes of a raised prolactin:

Prolactinoma

Drugs: All classes of psychotropic drugs, including dopamine-antagonists ( phenothiazine-type antipsychotics, antihistamines, and antiemetics e.g. metoclopramide), atypical antipsychotics, anti-depressants (tricyclics, SSRIs, MAOIs), cannabinoids, amphetamines, buspirone, alprazolam, domperidone, alpha-methyldopa, reserpine, verapamil, morphine, H2 antagonists, fenfluramine, physostigmine, estrogens (including OC).

Physical or psychological stress (illness, anaesthesia, surgery).

Non-functioning pituitary tumours causing pituitary stalk compression.

Macroprolactin : an elevated prolactin concentration may be due to the presence of macroprolactin, a biologically inactive prolactin-immunoglobulin complex which is cleared slowly from the plasma. The presence of macroprolactin has no clinical consequences, but may lead to unnecessary investigations.

At LabPlus, all samples with a raised prolactin concentration are routinely tested for the presence of macroprolactin. The level of monomeric (biologically active) prolactin is reported, as well as the total prolactin (monomeric prolactin + macroprolactin). If the monomeric prolactin is normal, no further investigations for prolactinoma are necessary.

Post-seizure : Prolactin may be elevated following a convulsion. Blood needs to be taken within 40 min of the event, and should be compared with a baseline sample taken before the event or a sample taken several hours later. However, a normal prolactin level does not discriminate between partial seizures (complex or simple) and non-epileptic events. The prolactin release may be blunted in the case of repetitive seizures.

Diurnal variation: prolactin levels are highest in early morning

Pregnancy: can peak up to 10,000 mIU/L in late pregnancy.

Lactation: peaks at 10 min. after starting breast feeding

Sexual intercourse.

Hypothyroidism

PCO syndrome

Conversion factor: ng/mL x 21.2 = mIU/L

References

1. Daria La Torre et al. Pharmacological causes of hyperprolactinaemia. Therapeutic and Clinical risk management 2007; 3(5): 929-951

2. Kyle, C. Sonic Pathology Handbook, 2014.

Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.

Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402

Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052

Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427

Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427

Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427

Specimen Transport Instructions for Referring Laboratories

Send a separated SST tube, or at least 300 uL serum aliquot. If analysis for macroprolactin in required, send a minimum of 500 uL. Transport at 4 ^o C.

Last updated at 15:26:00 06/01/2025