Interpresting Test Results
Prolactin Interpretation
Serum prolactin is the definitive test for diagnosing hyperprolactinaemia.1
Assessment of serum prolactin is usually straightforward and informs the need for further workup.1,2
< 25 µg/L // Normal value
Normal value
• Proceed with further clinical evaluation of symptoms
25-250 µg/L // Elevated value
Elevated value
• Refer to other laboratory results and the medical history to identify a secondary cause of hyperprolactinemia (eg, hypothyroidism, medications)
• Imaging may be needed to identify presence of a pituitary or hypothalamic mass
> 250 µg/L // Elevated value, typically indicative of a prolactinoma
Elevated value, typically indicative of a prolactinoma
• Consider MRI scan and/or referral to a neuroendocrinologist
Other Test Results
Aside from prolactin measurement, several other laboratory tests should be conducted during the workup of a patient with suspected hyperprolactinaemia as part of the differential diagnosis and to help identify a cause of hyperprolactinaemia, if present.1,2,4
Macroprolactin
• Recommended for patients with asymptomatic hyperprolactinemia
• Macroprolactinemia is a common cause of hyperprolactinaemia; however, many commercial assays do not detect large polymeric forms of prolactin (i.e., macroprolactin)
β-hCG (ß human chorionic gonadotropin)
• Mandatory for any woman of childbearing age with amenorrhoea to identify possible pregnancy
FSH (follicle-stimulating hormone), LH (luteinizing hormone)
• In patients with hyperprolactinaemia, levels are reduced due to prolactin interference with GnRH (gonadotropin-releasing hormone) secretion, leading to hypogonadism and infertility
TSH (Thyroid stimulating hormone)
• Useful for determining primary hypothyroidism, which can cause mild hyperprolactinaemia
• Normalization of thyroid function with levothyroxine leads to hyperprolactinaemia resolution
IGF-1 (Insulin growth factor)
• Required for all patients with macroadenomas to identify possible acromegaly
Renal function tests (e.g. creatinine)
• Useful for determining kidney dysfunction, which can cause prolactin to accumulate due to decreased clearance and enhanced production
Liver function tests
• Useful for determining hepatic insufficiency, which can cause prolactin to accumulate due to decreased clearance
References
1.Melmed S, Casanueva FF, Hoffman AR, et al; Endocrine Society. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(2):273-288.
2.Halperin Rabinovich I, Cámara Gómez R, García Mouriz M, Ollero García-Agulló D; Grupo de Trabajo de Neuroendocrinología de la SEEN. Clinical guidelines for diagnosis and treatment of prolactinoma and hyperprolactinemia. Endocrinol Nutr. 2013;60(6):308-319.
3.Majumdar A, Mangal NS. Hyperprolactinemia. J Hum Reprod Sci. 2013;6(3):168-175.
4.Vilar L, Fleseriu M, Bronstein MD. Challenges and pitfalls in the diagnosis of hyperprolactinemia. Arq Bras Endocrinol Metabol. 2014;58(1):9-22.
Selecting Treatment based on Guidelines
Determine therapy based on clinical and patient factors
Monitoring and Management
Learn how to tailor therapy based on follow-up testing
What is Hyperprolactinaemia?
See general information including pathophysiology and etiology
Identifying Common Symptoms
Understand what signs to look for and explore two patient cases
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