From the Guidelines
Recommended hormonal testing should include evaluating ACTH, cortisol, TSH, free T4, and electrolytes, with consideration of standard-dose ACTH stimulation testing for indeterminate results, as well as LH, testosterone, FSH, and estrogen in patients with specific symptoms such as fatigue, loss of libido, and mood changes. When evaluating patients with suspected hormonal deficiencies, it is essential to consider the clinical presentation and symptoms. According to the ASCO guideline update 1, the initial workup and evaluation should include assessing ACTH, cortisol, TSH, free T4, and electrolytes. Additionally, standard-dose ACTH stimulation testing should be considered for indeterminate results, such as morning cortisol levels between 3 mg/dL and 15 mg/dL. For patients presenting with symptoms like fatigue, loss of libido, and mood changes, further evaluation of LH, testosterone in males, FSH, and estrogen in premenopausal females is recommended 1. It is also crucial to consider imaging studies, such as MRI brain with or without contrast, particularly in patients with new hormonal deficiencies, multiple endocrine abnormalities, severe headaches, or complaints of vision changes 1. In contrast to other guidelines, such as the AUA guideline on evaluation and management of testosterone deficiency 1, which recommends measuring serum luteinizing hormone levels and prolactin levels in patients with low testosterone, the ASCO guideline update provides more comprehensive and recent recommendations for hormonal testing in the context of immune-related adverse events. Therefore, the recommended hormonal testing should prioritize the evaluation of ACTH, cortisol, TSH, free T4, and electrolytes, as well as consideration of LH, testosterone, FSH, and estrogen in patients with specific symptoms, as outlined in the ASCO guideline update 1. Key points to consider when ordering hormonal tests include:
- Evaluating ACTH, cortisol, TSH, free T4, and electrolytes as initial tests
- Considering standard-dose ACTH stimulation testing for indeterminate results
- Assessing LH, testosterone, FSH, and estrogen in patients with specific symptoms
- Ordering MRI brain with or without contrast in patients with new hormonal deficiencies or multiple endocrine abnormalities.
From the FDA Drug Label
Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid Monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status In patients with hypothyroidism, assess the adequacy of replacement therapy by measuring both serum TSH and total or free-T4. Monitor TSH and total or free-T4 in pediatric patients as follows: 2 and 4 weeks after the initiation of treatment, 2 weeks after any change in dosage, and then every 3 to 12 months thereafter following dosage stabilization until growth is completed For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy.
The recommended hormonal testing for patients taking levothyroxine includes:
- Serum TSH levels to assess the adequacy of therapy
- Free-T4 levels to assess the adequacy of therapy
- Total or free-T4 levels in pediatric patients to assess the adequacy of replacement therapy
- Monitoring of TSH and total or free-T4 levels at regular intervals, such as every 6 to 12 months in adult patients and every 3 to 12 months in pediatric patients after dosage stabilization until growth is completed 2
From the Research
Hormonal Testing Recommendations
The following hormones are recommended for testing based on the provided studies:
- Thyroid-stimulating hormone (TSH) 3, 4, 5, 6
- Free T4 (FT4) 4, 5, 6
- Free T3 (FT3) 4, 5
- Adrenocorticotropic hormone (ACTH) 3, 4
- Cortisol 3, 6
- Insulin 3
- Parathyroid hormone (PTH) 3
- Growth hormone (GH) 3
- Follicle-stimulating hormone (FSH) 3, 4
- Luteinizing hormone (LH) 3, 4
- Testosterone 3
- Aldosterone 3
- Renin 3
Testing Considerations
When interpreting TSH levels, consider the time interval between taking medication and withdrawing blood samples, especially in patients with treated Addison's disease 4. In patients with cortisol-producing adenoma, serum cortisol levels may be negatively associated with TSH and free T4 levels 6. Combined T3/T4 therapy may result in wide peak-to-trough variation in FT3 levels 5.
Additional Tests
Other tests that may be recommended based on the provided studies include: