From the Guidelines
The diagnostic workup for hypoprolactinemia in a non-pregnant woman should focus on ruling out underlying conditions that may be causing the low prolactin levels, such as energy deficiency-related amenorrhea, and assessing overall pituitary function. The evaluation should start with a thorough medical history, including menstrual irregularities, fertility issues, and symptoms like decreased libido or vaginal dryness. A comprehensive medication review is essential, as certain drugs can affect prolactin levels 1. Laboratory testing should confirm low prolactin with a morning fasting blood sample, and additional hormonal assessments, including FSH, LH, estradiol, and thyroid function tests, can help evaluate overall pituitary function.
Key Components of the Diagnostic Workup
- Thorough medical history
- Comprehensive medication review
- Laboratory testing for prolactin and other hormonal assessments
- Evaluation for energy deficiency-related amenorrhea, including consultation with a sports dietitian and bone mineral density test if necessary 1 ### Considerations for Further Testing If there are concerns about pituitary insufficiency, further testing for other pituitary hormones may be warranted. However, imaging studies like MRI of the pituitary are rarely needed unless other pituitary hormone deficiencies are present.
Treatment Approach
Treatment is typically not required for isolated hypoprolactinemia unless the patient is experiencing specific symptoms or fertility issues. Any treatment would focus on addressing the underlying cause rather than directly supplementing prolactin. Consultation with an endocrinologist may be necessary if the primary care provider is not experienced in treating endocrine disorders related to hypoprolactinemia 1.
From the Research
Diagnostic Workup for Hypoprolactinemia
The diagnostic workup for hypoprolactinemia in a non-pregnant woman involves several steps, including:
- Measuring basal prolactin levels, with cut-off levels of at least 5 ng/mL for males and 7 ng/mL for females considered normal 2
- Conducting a thyrotropin-releasing hormone (TRH) stimulation test to assess prolactin reserve, with minimum peak prolactin responses of 18 ng/mL for males and 41 ng/mL for females considered normal 2
- Evaluating for other pituitary hormone deficiencies, as hypoprolactinemia is often associated with multiple hormone deficiencies 3, 4
- Imaging studies, such as MRI or CT, to rule out pituitary tumors or other sellar masses 5, 6
Laboratory Tests
Laboratory tests used to diagnose hypoprolactinemia include:
- Serum prolactin levels, which should be measured using a sensitive assay to avoid false negatives 5
- TRH stimulation test, which can help diagnose hypoprolactinemia and assess prolactin reserve 2
- Other pituitary hormone levels, such as growth hormone, gonadotropins, and thyroid-stimulating hormone, to evaluate for multiple hormone deficiencies 3, 4
Clinical Evaluation
A clinical evaluation is also important in diagnosing hypoprolactinemia, including:
- Medical history, to identify any underlying conditions that may be contributing to hypoprolactinemia, such as pituitary tumors or hypothalamic-pituitary axis disease 3, 4
- Physical examination, to evaluate for signs of hypopituitarism, such as amenorrhea or galactorrhea 6
- Review of symptoms, such as infertility, sexual dysfunction, or metabolic disorders, which may be associated with hypoprolactinemia 2, 4