- Red or tiger top tube
- 5-7 mL of venous blood
Additional information
- Limit physical activity and fasting for 12 hrs before test
- Avoid stress, excitement, or stimulation for 30 minutes before test
- Sample drawn in the morning (between 8:00 and 10:00 am), 3-4 hours after awakening
- Sample should ideally be drawn in chilled tubes and the specimen kept on ice
- Handle sample gently to prevent hemolysis
- Send sample to lab immediately
- Prolactin assay measures the concentration of the hormone prolactin in the blood
- Prolactin is a polypeptide hormone secreted by lactotrophs of the anterior pituitary gland, primarily for the development of mammary glands for lactation during pregnancy and for stimulating and maintaining lactation postpartum
- This hormone is under the complex regulatory system of estrogen, progesterone, dopamine, thyrotropin-releasing hormone (TRH) and vasoactive intestinal peptides
- The function of prolactin in males is unknown
- Prolactin level elevates acutely in most epileptic seizures
- The clinical utility of prolactin assay includes:
- Evaluation of secondary amenorrhea and galactorrhea
- Aids in the diagnosis and management of hyperprolactinemia
- Evaluate failure of lactation or suspected postpartum hypophyseal infarction (Sheehan's syndrome) in the postpartum period
- Evaluation of infertility and sexual dysfunction in men and women
- Aids in the diagnosis, management, and follow-up of prolactin-secreting tumors or metastasis
- Evaluation of true epileptic seizures from non-epileptic "seizures"
- Elevation to 2 times baseline or >23 ng/mL (23 µg/L) drawn 10-20 minutes after the "event" is the threshold value
- Elevation of prolactin has a positive predictive value for true epileptic seizures of 93-99% and specificity of 96%
- Lack of elevation of prolactin after an "event" has 89% specificity for psychological non-epileptic seizure (e.g. pseudoseizures)
- To facilitate diagnosis of pituitary dysfunction, possibly due to pituitary adenoma
- To aid in diagnosis of hypothalamic dysfunction regardless of cause
- Hyperprolactinemia may clinically present as:
- Females
- Oligomenorrhea
- Amenorrhea
- Galactorrhea
- Infertility (anovulation)
- Osteoporosis
- Males
- Impotence
- Decreased libido
- Erectile dysfunction
- Infertility
- Abnormally high prolactin levels (100-300 ng/ml or 100-300 µg/L) suggest autonomous prolactin production by a pituitary adenoma, especially when amenorrhea or galactorrhea is present (Forbes-Albright syndrome). However, a normal prolactin level does not rule out pituitary tumor
- Elevated prolactin levels with normal menstruation and no galactorrhea is indicative of macroprolactin, a circulating complex of prolactin and immunoglobulins of no biological importance but gives a high reading in the prolactin assay
- Prolactin deficiency in pregnancy can lead to the absence of postpartum lactation
Additional information
- Prolactin levels rise late in pregnancy, peak with the initiation of lactation, and surge each time a woman breast-feeds
- Prolactin is higher in children, falls to adult levels by age 12, and decreases with increasing age in older adults
- In women, PRL increases during follicular phase to spike at the time of LH surge
- Circadian changes of prolactin can be seen with peak levels at night and early morning hours (sleep-induced peak), lowest in early afternoon
- Normal day-to-day variation is about 5-10% in men and 40% in women
- Prolactin levels should be interpreted with caution as they vary with sex, age, time of day, and the method of assay
- Elevated levels of prolactin should be confirmed with repeat measurements on 2 other occasions
- Prolactin levels, along with thyrotropin-releasing hormone (TRH) stimulation test, help to identify causes of galactorrhea such as pituitary tumors
- Factors interfering with test results include:
- Breast stimulation
- Recent surgery
- Recent seizure
- Radioactive scan performed within 1 wk before test (false elevations
- Failure to follow dietary restrictions
- Samples collected within 3 hours of waking (sleep-induced peak levels)
- Hemolysis due to rough handling of sample
- Venipuncture (falsely elevated levels)
- Presence of macroprolactin
- Related laboratory tests include:
- Dehydroepiandrosterone
- Follicle stimulating hormone (FSH)
- Human chorionic gonadotropin
- Luteinizing hormone (LH)
- Testosterone
- Thyroid function tests (T3, T4, TSH)
- Thyrotropin-releasing hormone (TRH) stimulation test
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
| Conv. Units (ng/mL) | SI Units (µg/L) | |
|---|---|---|
| Females (not pregnant and Not lactating) | 4-23 | 4-23 |
| Females (pregnant) | 30-400 | 30-400 |
| Males & Children | 3-20 | 3-20 |
Conditions associated with elevated prolactin levels (hyperprolactinemia) include:
- Physiological
- Newborns
- Pregnancy
- Postpartum period
- Stress
- Seizure
- Exercise
- Sleep
- Nipple stimulation
- Lactation (breast feeding)
- Smoking (in men)
- High altitude
- Hemoconcentration
- Hypoglycemia
- Non-neoplastic
- Afferent neural stimulation
- Chronic breast abscess
- Breast stimulation (even irritation by clothes)
- Mastectomy or other breast surgery
- Thoracotomy
- Syringomyelia
- Tabes dorsalis
- Endocrine
- Hypothyroidism (primary)
- Adrenal insufficiency
- Ovarian tumor
- Polycystic ovary syndrome
- Prolactin inhibiting factor (PIF) synthesis inhibition
- Hypothalamic cause
- Cerebrovascular infarction
- Prolactin inhibiting factor (PIF) transport interruption
- Cerebral aneurysm
- Cerebral cyst
- Pseudotumor cerebri
- Others
- Acute intermittent porphyria
- Cirrhosis
- Chronic renal failure
- Multiple sclerosis
- Anorexia nervosa
- HIV infection
- Systemic lupus erythematosus
- Frommel-Chiari Syndrome
- Argonz-Del Castillo syndromes
- Neoplasti
- Prolactin inhibiting factor (PIF) synthesis inhibition or transport interrupted by
- Hypothalmic tumors (primary and metastasis)
- Craniopharyngioma
- Pineal tumors (primary or metastatic)
- Pituitary tumors
- Compression of pituitary stalk (meningioma, CNS sarcoidosis, eosinophilic granuloma)
- Prolactin secreting tumors
- Pituitary tumors (Acromegaly, Cushing’s disease, Nelson disease)
- Acidophilic stem cell adenomas
- Ectopic tumor production (breast cancer, bronchogenic carcinoma, hypernephroma, leukemia)
- Others
- Hydatidiform mole
- Advanced multiple myeloma
- Drugs and substances
-Endorphin- Anise
- Arginine
- Azosemide
- Benserazide
- Benzamides (sulpiride, sultopride, remoxipride, veralipride)
- Butorphanol
- Butyrophenones (haloperidol
- Carbidopa
- Citalopram
- Cocaine
- Danazol
- Diethylstilbestrol
- Enalapril
- Estrogens
- Ethanol
- Fenfluramine
- Fenflurane
- Fennel
- Fenoldopam
- Fenugreek Seed
- Flunarizine
- Fluvoxamine
- Furosemide
- Gonadotropin-releasing hormone
- Growth hormone-releasing hormone
- H2 blockers (cimetidine, ranitidine, famotidine)
- Insulin
- Interferon-
- Interleukin
- Labetalol
- Loxapine
- Mestranol
- Methadone
- Methyldopa
- Metoclopramide
- Molindone
- Monoamine oxidase inhibitors (moclobemide)
- Morphine
- Nettle
- Nitrous oxide
- Opiates
- Oral contraceptives
- Oxcarbazepine
- Parathyroid hormone
- Pentagastrin
- Phenothiazines (chlorpromazine, promazine, trifluoperazine, thioridazine, fluphenazine, perphenazine, prochlorperazine, piparazines)
- Phenytoin
- Pimozide
- Propranolol (in men)
- Reserpine
- Risperidone
- Thioxanthenes (thiothixene)
- Thyrotropin-releasing hormone
- Tricyclic antidepressants (amitriptyline, amoxapine, clomipramine, desipramine, imipramine, thiethylperazine, trimipramine)
- Tumor necrosis factor
- Verapamil
- Zometapine
Conditions associated with decreased prolactin levels (hypoprolactinemia) include:
- Sheehan syndrome (pituitary apoplexy)
- Idiopathic hypogonadotropic hypogonadism
- Empty sella syndrome
- Parasellar diseases
- Head injury
- Infection (tuberculosis, histoplasmosis)
- Infiltrative diseases (sarcoidosis, hemochromatosis, lymphocytic hypophysitis)
- Irradiation
- Smoking (in women)
- Fasting
- Malnutrition
- Acute illness
- Drugs
- Anticonvulsants
- Apomorphine
- Bromocriptine
- Cabergoline
- Calcitonin
- Carbamazepine
- Conjugated estrogens
- Cyclosporine
- Dexamethasone
- Dopaminergic drugs (L-Dopa)
- Ergot alkaloids
- Erythropoietin (in renal failure)
- Finasteride
- Nifedipine
- Octreotide
- Rifampin
- Ritanserin
- Ropinirole
- Secretin
- Tamoxifen
- Terguride
- Thyroid hormones
- Valproic acid
- ARUP Laboratories®. Prolactin. [Homepage on the internet]©2007. Last accessed on June 22, 2007. Available at URL: http://www.aruplab.com/guides/ug/tests/0070115.jsp
- Chen DK, et al. Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the AmericanAcademy of Neurology. Neurology 2005;65(5):668-75.
- Donadio F et al. Patients with macroprolactinaemia: clinical and radiological features. Eur J Clin Invest. 2007 Jul;37(7):552-7.
- eMedicine from WebMD®. Hyperprolactinemia. [Homepage on the Internet] ©1996-2007. Last updated on October 18, 2005. Last accessed on June 22, 2007. Available at URL: http://www.emedicine.com/med/topic1098.htm
- eMedicine from WebMD®. Prolactin Deficiency. [Homepage on the Internet] ©1996-2007. Last updated on July 11, 2006. Last accessed on June 22, 2007. Available at URL: http://www.emedicine.com/med/topic1914.htm
- LeungAK et al. Diagnosis and management of galactorrhea.
Am Fam Physician. 2004 Aug 1;70(3):543-50. - Laboratory Corporation of America®. Prolactin. [Homepage on the internet]©2007. Last accessed on June22, 2007. Available at URL: http://www.labcorp.com/datasets/labcorp/html/chapter/mono/ri008700.htm
- Lab Tests online®. Prolactin. [Homepage on the Internet]©2001-2007. Last reviewed on September 11, 2006. Last accessed on June 22, 2007. Available at URL: http://www.labtestsonline.org/understanding/analytes/prolactin/glance.html
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- Manuchehri AM et al. Effect of dopamine agonists on prolactinomas and normal pituitary assessed by dynamic contrast enhanced magnetic resonance imaging (DCE-MRI). Pituitary. 2007 Jun 8; [Epub ahead of print]
- Thanqavelu K et al. Menstrual disturbance and galactorrhea in people taking conventional antipsychotic medications. Exp Clin Psychopharmacol. 2006 Nov;14(4):459-60.
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