The goals of pituitary disorder testing are to detect excess or deficient hormone production, determine its cause, and evaluate the severity of the condition. Testing frequently includes measurements of both the hormones that the pituitary produces, such as thyroid-stimulating hormone (TSH), and the hormones of other endocrine glands that the pituitary stimulates, such as the thyroid gland hormone thyroxine.
Pituitary hormones are released as needed so concentrations may be relatively constant in the blood (e.g., TSH), may vary over the course of a day (e.g., cortisol), or may vary over a cycle (e.g., FSH and LH during the menstrual cycle). Hormones may be present in specific situations, such as prolactin in lactating women or ACTH as a response to a physical or emotional stress. This variation in when hormones are released may mean that detecting excess and deficient hormones requires tests that measure hormonal changes after a person takes medications to suppress or stimulate hormones. Related tests may also be used, such as the measurement of IGF-1 (insulin-like growth factor-1), which reflects total growth hormone production, along with the measurement of growth hormone (GH).
Testing may be used to help diagnose a pituitary disorder and may be ordered at intervals to monitor the effectiveness of treatment over time, for a variety of reasons. Treatment may not completely resolve a condition or may cause additional pituitary dysfunction, either immediately or in the future (such as with surgery and radiation, respectively). Some individuals may have inherited conditions and thus a lifetime risk of developing a pituitary disorder, so long-term monitoring may be necessary in some cases.
Examples of laboratory tests used in the evaluation of pituitary disorders include:
- LH and FSH
- TSH and Thyroxine
- Basic metabolic panel (BMP)
- ACTH and Cortisol
- GH and IGF-1
- Water deprivation test, which involves measuring urine and serum osmolality; may be used to help diagnose diabetes insipidus
Examples of non-laboratory tests include:
- MRI (magnetic resonance imaging)
- CT (computed tomography)
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