Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

PROCT
83097
Clinical Information: Prolactin is secreted by the anterior pituitary gland and controlled by the
hypothalamus. It is structurally related to growth hormone (GH), but has few, if any, of the
physiological effects of GH. The major chemical controlling prolactin secretion is dopamine, which
inhibits prolactin secretion from the pituitary. The only definitively known physiological function of
prolactin is the stimulation of milk production. In normal individuals, the prolactin level rises in
response to physiologic stimuli such as sleep, exercise, nipple stimulation, sexual intercourse,
hypoglycemia, postpartum period, and also is elevated in the newborn infant. Pathologic causes of
hyperprolactinemia include prolactin-secreting pituitary adenoma (prolactinoma, which is 5 times more
frequent in females than males), functional and organic disease of the hypothalamus, primary
hypothyroidism, section compression of the pituitary stalk, chest wall lesions, renal failure, and ectopic
tumors. Hyperprolactinemia often results in loss of libido; galactorrhea, oligomenorrhea or amenorrhea,
and infertility in premenopausal females; and loss of libido, impotence, infertility, and hypogonadism in
males. Postmenopausal and premenopausal women, as well as men, can also suffer from decreased
muscle mass and osteoporosis. The latter can sometimes be dramatic in a small subgroup of women
who develop severe and acute onset postpartum osteoporosis that remits with cessation of breastfeeding
and medical suppression of hyperprolactinemia.
Useful For: Aiding in evaluation of pituitary tumors, amenorrhea, galactorrhea, infertility, and
hypogonadism Monitoring therapy of prolactin-producing tumors
Interpretation: In males, prolactin levels >13 ng/mL are indicative of hyperprolactinemia. In
women, prolactin levels >27 ng/mL in the absence of pregnancy and postpartum lactation are indicative
of hyperprolactinemia. Clear symptoms and signs of hyperprolactinemia are often absent in patients
with serum prolactin levels 250 ng/mL are usually associated
with a prolactin-secreting tumor. After initiation of medical therapy of prolactinomas, prolactin levels
should decrease substantially in most patients; in 60% to 80% of patients, normal levels should be
reached. Failure to suppress prolactin levels may indicate tumors resistant to the usual central-acting
dopamine agonist therapies; however, a subset of patients will show tumor shrinkage despite persistent
hyperprolactinemia. Patient who show neither a decrease in prolactin levels nor tumor shrinkage might
require additional therapeutic measures. Resurgent prolactin levels in patients on long-term therapy
indicate, most often, noncompliance with dopaminergic therapy, but can occasionally be an indication
of recurrence.
Reference Values:
Males: 3-13 ng/mL
Females: 3-27 ng/mL
Clinical References: Demers LM, Vance ML: Pituitary function. In Tietz Textbook of Clinical
Chemistry and Molecular Diagnostics. 4th edition. Edited by CA Burtis, ER Ashwood, DE Bruns. St.
Louis, Elsevier Saunders Company, 2006, pp 1976-1981
Prolonged Clot Time Profile
Clinical Information: When coagulation screening tests are performed to verify normal function of
the coagulation system (eg, preoperative, routine examination), they sometimes indicate an abnormality
that may be unexplained (ie, prolonged clotting times). This consultation provides validation of the
prolongation and as comprehensive a work-up as needed to define the abnormality. Possibilities for a
cause of prolongation include: -Factor deficiency(ies), congenital or acquired -Factor inhibitors
(including Coumadin therapy) -Lupus-like anticoagulant -Heparin contamination -Dilution of specimen
by anticoagulant if patient hematocrit is > or =55%
Useful For: Determining cause of prolongation of prothrombin time or activated partial
thromboplastin time Screening for prolonged clotting times and determining the presence of factor
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