From the Guidelines
Pituitary function is best assessed through a combination of blood tests, including ACTH, cortisol, TSH, free T4, and electrolytes, as well as consideration of LH, FSH, and testosterone or estrogen levels in patients with specific symptoms, and imaging studies like MRI with contrast for anatomical evaluation. The assessment of pituitary function involves evaluating the gland's ability to produce and regulate various hormones essential for bodily functions. According to the most recent and highest quality study 1, the initial workup should include evaluating ACTH (AM), cortisol (AM), TSH, free T4, and electrolytes.
Key Tests for Pituitary Function
- Blood tests for baseline hormone levels: ACTH, cortisol, TSH, free T4, electrolytes
- Consideration of LH, FSH, and testosterone in males or estrogen in premenopausal females with symptoms like fatigue, loss of libido, and mood changes
- Standard-dose ACTH stimulation testing for indeterminate results
- MRI brain with or without contrast with pituitary or sellar cuts in patients with new hormonal deficiencies, particularly those with multiple endocrine abnormalities, new severe headaches, or complaints of vision changes
The choice of tests depends on the clinical presentation and suspected abnormalities. For instance, patients presenting with diabetes insipidus should undergo MRI brain with or without contrast with pituitary or sellar cuts 1. It's also important to consider the potential risks and the need for careful monitoring during some stimulation tests, emphasizing the role of endocrinologist supervision.
Importance of Recent Guidelines
The 2021 update on the management of immune-related adverse events in patients treated with immune checkpoint inhibitor therapy 1 provides the most current guidance on assessing pituitary function, highlighting the importance of a thorough initial evaluation and the selective use of additional tests based on clinical findings. This approach ensures that patients receive appropriate and timely care for potential pituitary dysfunction, which can significantly impact morbidity, mortality, and quality of life.
From the FDA Drug Label
The intravenous infusion of R-Gene® 10 is a part of the test for measurement of pituitary reserve of human growth hormone Test Procedure ... 7 Diagnostic test results showing a deficiency of pituitary reserve for HGH should be confirmed by a second test with R-Gene® 10, or one may elect to confirm with the insulin hypoglycemia test. If the insulin hypoglycemia test has indicated a deficiency of pituitary reserve for HGH, a test with R-Gene® 10 is advisable to confirm the negative response
The tests used to assess pituitary function are:
From the Research
Tests for Pituitary Function
To assess pituitary function, several tests can be used, including:
- Growth hormone (GH) stimulation tests, which may be required to diagnose growth hormone deficiency (GHD) 3
- Insulin tolerance test (ITT), which can be used as a reference test to evaluate adrenal function in patients with hypothalamic-pituitary disorders 4
- Human-corticotrophin releasing hormone (h-CRH) test, which can be used to assess adrenal function in patients with hypothalamic-pituitary disorders 4
- Adrenocorticotropic hormone (ACTH) stimulation test, which can be used to assess the hypothalamo-pituitary-adrenocortical axis 5
- Measurement of serum cortisol, luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin levels, which can be used to evaluate pituitary function and diagnose conditions such as hypogonadism and hyperprolactinemia 6
Specific Tests for Pituitary Hormones
For specific pituitary hormones, the following tests can be used:
- GH: GH stimulation tests, such as the insulin tolerance test or the arginine test 3
- Adrenocorticotropic hormone (ACTH): ACTH stimulation test, such as the 1 microgram ACTH test or the 250 micrograms ACTH test 5
- Thyroid-stimulating hormone (TSH): measurement of TSH levels, which can be used to evaluate thyroid function 7
- LH and FSH: measurement of LH and FSH levels, which can be used to evaluate gonadal function 6
- Prolactin: measurement of prolactin levels, which can be used to diagnose hyperprolactinemia 6
Interpretation of Test Results
When interpreting test results, it is essential to consider individual patient factors, such as age and sex, as well as the specific test used and the reference range for that test 3, 5, 4. Additionally, the results of multiple tests may need to be considered together to make an accurate diagnosis 6, 4.