Initial Laboratory Workup for Galactorrhea
The initial laboratory workup for a patient presenting with galactorrhea should include serum prolactin measurement, thyroid-stimulating hormone (TSH), pregnancy test (in women of reproductive age), and assessment of renal function. 1
Essential Laboratory Tests
- Serum prolactin level: This is the cornerstone test for all patients with galactorrhea, as recommended by the Endocrine Society 1
- Pregnancy test: Should be obtained for all premenopausal women presenting with galactorrhea to rule out physiologic causes 2
- Thyroid-stimulating hormone (TSH): Essential to evaluate for hypothyroidism, which is a common cause of galactorrhea even with normal prolactin levels 1, 3
- Renal function tests: Should be included in the initial workup as chronic renal failure can cause hyperprolactinemia 2
Additional Testing Based on Initial Results
- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): Should be considered if amenorrhea is present 1
- Assessment for macroprolactin: Should be performed if prolactin is elevated but clinical features are inconsistent with hyperprolactinemia 1
- Serial prolactin measurements: For mildly elevated prolactin levels, consider collecting samples at 20-60 minute intervals using an indwelling cannula to exclude stress-related hyperprolactinemia 1
Imaging Studies
- High-resolution pituitary MRI: Should be performed if hyperprolactinemia is confirmed and no other cause (medication, thyroid dysfunction, renal impairment, pregnancy) is identified 1, 2
Common Pitfalls to Avoid
- Failing to check prolactin levels: Even when there are no other symptoms, prolactin should always be measured in patients with galactorrhea 1
- Not performing dilutions when measuring prolactin: In patients with large pituitary lesions, this can lead to falsely low results due to "hook effect" 1
- Overlooking normal prolactin galactorrhea: Not all cases of galactorrhea are associated with elevated prolactin levels, particularly in mild hypothyroidism 3
- Medication review omission: Failing to thoroughly review medications that can cause hyperprolactinemia (antipsychotics, antidepressants, antihypertensives, etc.) 4
Medication-Induced Galactorrhea
- Always perform a comprehensive medication review, as medication-induced galactorrhea is one of the most common causes after infancy 5
- Consider discontinuation or replacement of medications causing hyperprolactinemia with alternatives from similar classes with lower potential for causing this side effect 4