luteotropic hormone

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Related to luteotropic hormone: luteinizing hormone, luteotrophic hormone

luteotropic hormone (LTH),

an anterior pituitary hormone that acts to maintain the function of the corpus luteum.
Farlex Partner Medical Dictionary © Farlex 2012


A gonadotropic hormone encoded by PRL on chromosome 6p22.2-p21.3 and secreted by the anterior pituitary, which in females stimulates mammary gland growth and lactation after childbirth.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


An anterior pituitary hormone that acts to maintain the function of the corpus luteum.
Compare: bioregulator
Synonym(s): luteotropic hormone.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Synonym/acronym: Luteotropic hormone, lactogenic hormone, lactogen, HPRL, PRL.

Common use

To assess for lactation disorders and identify the presence of prolactin-secreting tumors to assist in diagnosing disorders such as lactation failure.


Serum (1 mL) collected in a gold-, red-, or red/gray-top tube. Specimen should be transported tightly capped and in an ice slurry.

Normal findings

(Method: Immunoassay)
AgeConventional UnitsSI Units (Conventional Units × 1)
Prepubertal males and females3.2–20 ng/mL3.2–20 mcg/L
Adult males4–23 ng/mL4–23 mcg/L
Adult females4–30 ng/mL4–30 mcg/L
 Pregnant5.3–215.3 ng/mL5.3–215.3 mcg/L
Postmenopausal2.4–24 ng/mL2.4–24 mcg/L


Prolactin is a hormone secreted by the pituitary gland. It is normally elevated in pregnant and lactating females. The main function of prolactin is to induce and sustain milk production in lactating females. Prolactin levels rise late in pregnancy, peak with the initiation of lactation, and surge each time a woman breastfeeds. Prolactin levels are highest at night during sleep and shortly after awakening. Levels are known to increase during periods of physical and emotional stress. Elevated prolactin levels are also known to affect fertility by inhibiting secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus; thereby also inhibiting secretion of LH and FSH from the pituitary gland and suppressing ovulation. Reduced fertility during lactation offers some natural protection against pregnancy. The function of prolactin in males and nonpregnant females is unknown but there is an association between high levels and infertility.

This procedure is contraindicated for



  • Assist in the diagnosis of primary hypothyroidism, as indicated by elevated levels
  • Assist in the diagnosis of suspected tumor involving the lungs or kidneys (elevated levels indicating ectopic prolactin production)
  • Evaluate failure of lactation in the postpartum period
  • Evaluate sexual dysfunction of unknown cause in men and women
  • Evaluate suspected postpartum hypophyseal infarction (Sheehan’s syndrome), as indicated by decreased levels

Potential diagnosis

Increased in

  • Adrenal insufficiency (secondary to hypopituitarism)
  • Amenorrhea (pathophysiology is unclear)
  • Anorexia nervosa (pathophysiology is unclear)
  • Breastfeeding (stimulates secretion of prolactin)
  • Chiari-Frommel and Argonz–Del Castillo syndromes (endocrine disorders in which pituitary or hypothalamic tumors secrete excessive amounts of prolactin)
  • Chest wall injury (trauma in this location can stimulate production of prolactin)
  • Chronic renal failure (related to decreased renal excretion)
  • Ectopic prolactin-secreting tumors (e.g., lung, kidney)
  • Galactorrhea (production of breast milk related to prolactin-secreting tumor)
  • Hypothalamic and pituitary disorders
  • Hypothyroidism (primary) (related to pituitary gland dysfunction)
  • Pituitary tumor
  • Polycystic ovary (Stein-Leventhal) syndrome
  • Pregnancy
  • Shingles
  • Stress (stimulates secretion of prolactin)
  • Surgery (pituitary stalk section)

Decreased in

    Sheehan’s syndrome (severe hemorrhage after obstetric delivery that causes pituitary infarct; secretion of all pituitary hormones is diminished)

Critical findings


Interfering factors

  • Drugs and hormones that may increase prolactin levels include amitriptyline, amoxapine, azosemide, benserazide, butaperazine, butorphanol, carbidopa, chlorophenylpiperazine, chlorpromazine, cimetidine, clomipramine, desipramine, diethylstilbestrol, enalapril, β-endorphin, enflurane, fenfluramine, fenoldopam, flunarizine, fluphenazine, fluvoxamine, furosemide, growth hormone–releasing hormone, haloperidol, hexarelin, imipramine, insulin, interferon-b, labetalol, loxapine, megestrol, mestranol, methyldopa, metoclopramide, molindone, morphine, nitrous oxide, oral contraceptives, oxcarbazepine, parathyroid hormone, pentagastrin, perphenazine, phenytoin, pimozide, prochlorperazine, promazine, ranitidine, remoxipride, reserpine, sulpiride, sultopride, thiethylperazine, thioridazine, thiothixene, thyrotropin-releasing hormone, trifluoperazine, trimipramine, tumor necrosis factor, veralipride, verapamil, and zometapine.
  • Drugs and hormones that may decrease prolactin levels include anticonvulsants, apomorphine, bromocriptine, cabergoline, calcitonin, cyclosporine, dexamethasone, d-Trp-6-LHRH, levodopa, metoclopramide, morphine, nifedipine, octreotide, pergolide, ranitidine, rifampin, ritanserin, ropinirole, secretin, and tamoxifen.
  • Episodic elevations can occur in response to sleep, stress, exercise, hypoglycemia, and breastfeeding.
  • Prolactin secretion is subject to diurnal variation with highest levels occurring in the morning.
  • Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient that test can assist in evaluating breast feeding hormone level.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s endocrine and reproductive systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Specimen collection should occur between 8 and 10 a.m. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to fast for 12 hr before specimen collection because hyperglycemia can cause a short-term increase in prolactin levels.
  • Note that there are no fluid or medication restrictions unless by medical direction.
  • Prepare an ice slurry in a cup or plastic bag to have on hand for immediate transport of the specimen to the laboratory.


  • Potential complications: N/A
  • Ensure that the patient has complied with dietary restrictions; ensure that food has been restricted for at least 12 hr prior to the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis. The specimen should be placed in an ice slurry immediately after collection. Information on the specimen label should be protected from water in the ice slurry by first placing the specimen in a protective plastic bag.


  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Instruct the patient to resume usual diet, as directed by the HCP.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include ACE, BMD, CT pituitary, DHEAS, estradiol, FSH, GH, HCG, insulin, laparoscopy gynecologic, LH, MRI pituitary, progesterone, RAIU, TSH, and thyroxine.
  • Refer to the Endocrine and Reproductive systems tables at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners