Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 ml whole blood light green top tube

Testing
Schedule:

Batch analysis performed on Tuesdays and Fridays.  Sample must 
be received by 0800 for same day service.

Reference Range:

MALES:    4.0 to 15.2 ng/ml
FEMALES:  4.8-23.3 ng/ml

Comments:

All samples are tested for the presence of macroprolactin.  A decrease 
of greater than 50% when precipitated with polyethylene glycol 
indicates the prossible presence of macroprolactin.

Immunoassay method instituted 3/21/00.

Test
Limitations:

The assay is unaffected by icterus (bilirubin is less than 30 mg/dl), 
hemolysis = 1500 (Hb is less than 1 g/dl), lipemia (Intralipid is less 
than 1500 mg/dl) and biotin is less than 100 ng/ml (criterion: recovery 
within plus or minus 10% of initial value).

In patients receiving therapy with high biotin doses (i.e. is greater 
than 5 mg/day) no sample should be taken until at least 8 hours after 
the last biotin administration.

No interference was observed from rheumatoid factor (up to approx. 1700 
U/ml) and samples from dialysis patients.

No high dose hook effect at prolactin concentrations of up to 200 000 
µIU/ml (9440 ng/ml).

In vitro tests were performed on 17 commonly used pharmaceuticals.

No interference with the assay was found.

As with all tests containing monoclonal antibodies, erroneous findings 
may be obtained from samples taken from patients who have been treated 
with monoclonal mouse antibodies or who have received them for 
diagnostic purposes. In rare cases, interference due to extremely high 
titers of antibodies to ruthenium can occur.

Prolactin contains additives which minimize these effects.

Extremely high titers of antibodies to streptavidin can occur in 
isolated cases and cause interference.

When determining prolactin it should be remembered that the measured 
concentration is dependent upon when the blood sample was taken, since 
the secretion of prolactin occurs in episodes and is also subject to a 
24-hour cycle. The release of prolactin is promoted physiologically by 
suckling and stress. In addition, elevated serum prolactin 
concentrations are caused by a number of pharmaceuticals  (e. g. 
dibenzodiazepines, phenothiazine), TRH and estrogen.(1-3)

The release of prolactin is inhibited by dopamine, L-dopa and 
ergotamine derivatives.

A number of publications report the presence of macroprolactin in the 
serum of female patients with various endocrinological diseases or 
during pregnancy.(4,5,6)  Differing degrees of detection of the serum 
macroprolactins (ultra-big is greater than 160 kD) relative to 
monomeric prolactin (22-23kD) by various immuno-assays have also been 
described. This could make the detection of hyperprolac tinemia 
dependent on the immunoassay used.(5)

The prolactin assay also encompasses macroprolactin. Accordingly, 
higher values may occasionally be found in patient samples than with 
other assay procedures.

For diagnostic purposes, the prolactin findings should always be 
assessed in conjunction with the patient's medical history, clinical 
examination and other findings.


(1) Frantz AG. Prolactin. New Engl J Med 1978;298:201-207.

(2) Müller EE et al. Prolactin-Lowering and -Releasing Drugs, Mechanism
    of Action and Therapeutic Applications. Drugs 1983;25:399-432.

(3) Pontiroli AE et al. Clinical, Endocrine, Roentgenographic and
    Immune Characterization of Hyperprolactinemic Women. Int J
    Fert1987;32:81-85.

(4) Smith CR, Norman MR. Prolactin and growth hormone: molecular
    heterogeneity and measurement in serum. Ann Clin Biochem. 1990;
    27:542-550.

(5) Dericks-Tan JSE, Siedentopf HG, Taubert HD. Discordant Prolactin
    Values obtained with Different Immunoassays in an infertile
    Patient. J Lab Med 1997;21(9):465-470.

(6) Leite V, Cosby H, Sobrinho LG, Fresnoza A, Santos MA, Friesen HG.
    Characterization of big-big prolactin in patients with
    hyperprolactinoma. Clin Endocrinol 1992;37:365-372.

Methodology:

Electrochemiluminescence Immunoassay

Sample
Processing:

Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.

Sample
Storage:

Refrigerate.

Transport
Instructions:

Place specimen into zip-lock type bag, seal bag.
Place requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

84146