From the Guidelines
To evaluate for a pituitary disorder, I recommend starting with a comprehensive panel of blood tests including morning cortisol, ACTH, TSH, free T4, and electrolytes, as outlined in the 2021 ASCO guideline update 1. When evaluating pituitary disorders, it is essential to consider the various hormonal axes controlled by the pituitary gland.
- The initial workup should include:
- Morning cortisol and ACTH levels to assess adrenal function
- TSH and free T4 to evaluate thyroid function
- Electrolyte panel to assess for any imbalances
- Additional tests may be considered based on patient symptoms, such as:
- LH and testosterone in males with fatigue, loss of libido, and mood changes
- FSH and estrogen in premenopausal females with oligomenorrhea or other hormonal symptoms
- Imaging studies, particularly an MRI of the brain with pituitary or sellar cuts, are crucial in evaluating patients with new hormonal deficiencies, multiple endocrine abnormalities, severe headaches, or vision changes, as recommended in the 2021 ASCO guideline update 1.
- Dynamic testing, such as standard-dose ACTH stimulation testing, may be necessary for indeterminate results, as outlined in the guideline 1. The specific combination of tests should be tailored based on presenting symptoms, and follow-up testing may be required to monitor treatment response or disease progression.
From the Research
Laboratory Tests for Pituitary Disorders
The following laboratory tests are used to evaluate pituitary disorders:
- Baseline blood sampling for thyroid stimulating hormone, gonadotropin, and prolactin deficiencies 2
- Dynamic stimulation tests for adrenocorticotropic hormone (ACTH), growth hormone, and antidiuretic hormone deficiency 2
- Hormone level assessments, including growth hormone (GH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), adrenocorticotropic hormone (ACTH), and antidiuretic hormone (ADH) 3
- Insulin-like growth factor-I and free thyroxine tests for growth and thyroid dysfunction 4
Specific Tests
Some specific tests used to evaluate pituitary disorders include:
- Thyroid function tests, such as TSH and free thyroxine (FT4) 5
- Growth hormone stimulation tests 4
- Adrenocorticotropic hormone (ACTH) stimulation tests 2
- Antidiuretic hormone (ADH) tests 2
Diagnostic Challenges
Diagnosing pituitary disorders can be challenging due to the variability of clinical manifestations and the lack of distinct dividing lines or gold standard diagnostic tests 4. Laboratory tests can contribute to the diagnostic process, but issues relating to assay harmonization and diagnostic thresholds need to be addressed 4.