Pituitary Tumor and Disorder Diagnosis

January 8, 2026

This page was reviewed under our medical and editorial policy by Behrouz Salehian M.D., clinical professor, Department of Diabetes, Endocrinology & Metabolism, City of Hope^® Cancer Center Duarte.

When diagnosing pituitary tumors or disorders, the patient’s care team will recommend tests based on his or her individual symptoms — which can differ depending on tumor type or condition.

The results of blood tests, imaging and vision exams help the care team better understand what’s happening and guide the optimal treatment plan.

Pituitary Tumor Diagnosis and Testing

If the care team suspects a pituitary tumor or cyst, several tests may be used to confirm the diagnosis and understand how it’s affecting the patient’s health. Firstly, the doctor will review the patient’s medical and family history to check for symptoms or inherited conditions, like multiple endocrine neoplasia. The next step is a physical exam to look for signs of a pituitary-related problem, including checks for nervous system changes and hormonal secretion.

Other tests may include:

Blood and urine tests to check hormone levels and determine if the pituitary gland is making too much or too little of certain hormones.

Imaging scans, most often a magnetic resonance imaging (MRI) scan of the pituitary gland, which provides detailed pictures of the pituitary gland and surrounding structures.

Vision tests to look for changes in eyesight, especially side (peripheral) vision, if the tumor or cyst is pressing on nearby nerves.

Together, these tests help the care team understand the size and location of the tumor or cyst, whether it’s affecting nearby structures and how it may be impacting hormone function.

Pituitary Adenoma Tests

Many pituitary adenomas are found by chance during routine imaging, such as a CT scan. To look more closely, doctors usually order an MRI with contrast (gadolinium), which helps show the difference between a tumor and other issues, like an aneurysm, and can also check for bleeding inside the tumor.

Even if the patient doesn’t have symptoms, the care team will usually recommend blood tests to measure hormone levels. This helps determine if the adenoma is affecting hormone production — either too little (hypopituitarism) or too much (hormone hypersecretion). Tests often include checking levels of growth hormone (GH and IGF-1), reproductive hormones (estradiol, testosterone, FSH, LH), prolactin (the milk secreting hormone), thyroid hormones (TSH and free T4), ACTH and cortisol for assessing adrenal function, in addition to other basic labs.

Pituitary Disorder Diagnosis

As part of the pituitary disorder diagnostic process, the care team may order some basic pituitary function tests to check how well the patient’s pituitary gland is working. Through a simple blood test, they can measure important hormones such as cortisol, thyroid hormones, prolactin, estrogen, testosterone and growth hormone. Depending on the results, other tests may follow.

The most important hormone of the pituitary is adrenocorticotropin hormone (ACTH), which stimulates the adrenal glands to secrete cortisol, the steroid that controls blood pressure and tonicity of the arterial wall. Lack of ACTH is associated with low serum cortisol and hypotension, especially during stressful situations such as high fever, accidents, operations and anesthesia.

Common Pituitary Function Tests

• ACTH and cortisol: This test should be done early in the morning to assess morning cortisol secretion. In case of sudden damage to the pituitary or adrenal glands, the serum levels of the two interacting hormones is extremely valuable for the diagnosis of acute adrenal insufficiency.
• ACTH stimulation test: This is a morning blood test to check cortisol and ACTH levels at baseline and after stimulation of the adrenals with intravenous bovine ACTH, measuring blood cortisol 30 and 60 minutes after the stimulation. The test demonstrates whether the patient has low cortisol (hypoadrenalism) and if there is a lack of cortisol response during stressful situations.
• Dexamethasone suppression test: The patient takes a tablet at night, followed by a blood test the next morning to check for excess cortisol. The test helps to screen for Cushing’s syndrome and excess cortisol production.
• FSH and LH tests: These blood tests measure reproductive hormones and are important for fertility, estrogen and testosterone. The test should be associated with measurements of estradiol or testosterone levels.
• IGF-1 test: This blood test monitors growth hormone activity, especially in acromegaly.
• Glucose tolerance test with GH measurements: The patient consumes a sugary drink, followed by several blood tests, to assess whether there is normal growth hormone suppression.
• Insulin stress test: The patient receives intravenous insulin with repeated blood tests to evaluate cortisol and growth hormone levels. This test is rarely used in the United States due to hypoglycemia and its risk in case of adrenal insufficiency.
• Water deprivation test: After fasting overnight without food or water, the care team monitors the patient’s blood pressure, weight, blood sodium levels, osmolality and urine concentration. Next, arginine vasopressin is injected to diagnose different type of diabetes insipidus (arginine vasopressin deficiency versus nephrogenous diabetes insipidus).