A 25-year-old Ms. Li visited hospital due to persistent acne. Blood tests showed her prolactin was more than twice the upper normal limit, accompanied by insulin resistance; all other hormone indicators were normal and her menstrual cycle remained regular. Her doctor advised repeat testing, reminding her that hyperprolactinemia may stem from pituitary adenoma. Many patients share the same doubt: does high prolactin necessarily mean a pituitary tumor? Is brain MRI mandatory?

1. High prolactin does not equal pituitary adenoma

With advances in modern endocrinology, ultrasensitive radioimmunoassays can precisely quantify hypothalamic and pituitary hormones, alongside standardized pituitary function provocation tests. These tools are critical for early diagnosis of pituitary adenomas, monitoring post-treatment changes, evaluating therapeutic response and long-term prognosis assessment.

Pituitary hormones are secreted in pulsatile patterns with distinct circadian rhythms, susceptible to internal and external physical stimuli. A single random prolactin reading is unreliable. Multiple blood draws at different time points combined with pituitary functional tests are required for accurate judgment. One isolated elevated prolactin result cannot confirm pituitary adenoma.

Definitive diagnosis of pituitary adenoma relies on comprehensive evaluation including characteristic clinical manifestations, visual field/cranial nerve impairment, endocrine panels and brain imaging. Typical cases are straightforward to classify, yet early microadenomas often present subtle or non-specific symptoms, ambiguous endocrine findings and negative imaging. Even if patients display isolated clinical, neurological, hormonal or radiological abnormalities—or all four simultaneously—pituitary adenoma cannot be diagnosed arbitrarily. Clinicians must gather multi-dimensional clinical data, conduct differential diagnosis and rule out alternative disorders before confirming the presence of a pituitary adenoma.

Multiple causes of hyperprolactinemia

Prolactin (PRL) secreted by pituitary lactotrophs is tightly regulated by the hypothalamus and easily disturbed by numerous triggers.

Normal reference range: female PRL ≤30μg/L, male PRL ≤20μg/L (≈800 mIU/L).

1. PRL > 100μg/L: Highly suggestive of prolactinoma

2. PRL > 300μg/L: Almost diagnostic of prolactin-secreting adenoma

3. PRL ranging 30–100μg/L: Multiple reversible non-tumor triggers exist

• Hormonal interference: excess GH, TRH, GnRH

• Medication-induced: certain antihypertensives, opiates, chlorpromazine and other antipsychotics

• Structural damage to hypothalamus / pituitary stalk: trauma, non-prolactin tumors, inflammation, hemorrhage, which disrupt secretion of prolactin-inhibiting factor (PIF)

Notably, non-functioning macroadenomas, GH adenomas and ACTH adenomas may also cause mild PRL elevation (30–100μg/L) via stalk compression. Such cases cannot be misdiagnosed as pure prolactinoma or mixed adenoma.

Auxiliary provocation/suppression tests (TRH stimulation, chlorpromazine stimulation, arginine stimulation; L-dopa / bromocriptine suppression) help differentiate the source of elevated prolactin by modulating hypothalamic PIF and prolactin-releasing factor (PRF) secretion.

2. When brain pituitary MRI is necessary

MRI screening is not required for every mild hyperprolactinemia patient. Indications for pituitary contrast-enhanced MRI include:

1. PRL persistently >100μg/L after repeated testing;

2. Classic clinical manifestations of prolactinoma: irregular menstruation, galactorrhea, infertility, decreased libido, visual blurring;

3. Unexplained persistent hyperprolactinemia after ruling out drugs, stress, sleep, exercise and thyroid dysfunction;

4. Combined other pituitary hormone abnormalities or visual field defects.

For Ms. Li with only two-fold PRL elevation, regular menstruation and no galactorrhea, doctors will first arrange repeat fasting morning prolactin testing, thyroid function screening and medication history review before deciding whether MRI is needed.

3. Treatment of pituitary adenoma: Medication vs Surgery

Indications for surgical resection

Most prolactinomas respond well to dopamine agonist medical therapy. Surgery is indicated under the following circumstances:

• Hormone hypersecretion cannot be controlled by standard-dose medication;

• Tumor mass effect compresses optic apparatus or cranial nerves, causing visual loss, headache or neurological deficits;

• Tumor continues to enlarge despite standardized drug treatment;

• Drug intolerance, severe side effects or patient refusal of long-term medication.

Two mainstream surgical approaches

1. Minimally invasive endoscopic transsphenoidal surgery

First-line resection technique for the majority of pituitary adenomas. Surgeons access the sellar region via the sphenoid sinus behind the nasal cavity, utilizing a fiber-optic neuroendoscope with micro-camera. A tiny incision is made posterior to the nasal septum for tumor removal. For special anatomical variants, a minimal labiogingival incision below the upper lip may be adopted to open the sphenoid wall.

2. Microsurgical craniotomy

Reserved for highly complex, giant or laterally extensive pituitary adenomas. A small craniotomy window is created on the frontolateral skull base. While effective for complicated lesions, it carries higher risks of cerebral tissue injury compared to transsphenoidal corridors. Preoperative CT/MRI precisely maps tumor location.

Potential surgical complications

Pituitary adenoma resection is technically sophisticated with inherent risks including infection, hemorrhage and anesthetic adverse reactions. Transsphenoidal patients commonly experience sinus headache resolving within weeks. Intraoperative hazards include injury to adjacent internal carotid arteries, brain parenchyma and cranial nerves, potentially leading to permanent visual loss or cerebral damage. Transient or permanent diabetes insipidus may occur, managed with desmopressin nasal spray for persistent cases. Meningitis can develop due to temporary communication between intracranial space and paranasal sinuses. Pituitary parenchymal damage may trigger panhypopituitarism requiring lifelong hormone replacement.

4. Professor Sebastien Froelich's “Chopstick Technique”: Reducing endoscopic surgical risks

Traditional neuroendoscopic transsphenoidal surgery demands high equipment standards, steep learning curves and coordinated two-surgeon teamwork, which raises operational difficulty and procedural errors. Professor Sebastien Froelich (member of INC World Neurosurgery Advisory Group, former Chairman of WFNS Skull Base Surgery Committee) pioneered the revolutionary “chopstick technique” to resolve these limitations.

Core principle of the chopstick technique

The surgeon holds the endoscope and suction device simultaneously in the left hand, mimicking chopstick grip; the right hand independently manipulates surgical instruments (drills, bipolar forceps, scissors).

Advantages:

• Single-operator independent operation, eliminating coordination delays between two surgeons;

• Sustained, precise continuous suction clears blood and smoke throughout dissection, maintaining a clean unobstructed surgical field;

• Supports multi-functional maneuvers: bony drilling, electrocoagulation hemostasis, tissue traction and sharp cutting;

• Minimizes nasal mucosal trauma, lowers postoperative CSF leak and infection risks.

This technique drastically improves gross total resection accuracy and safety. Professor Froelich is globally renowned for his masterful endoscopic skills; seamless coordination between the endoscope and chopstick method enables maximal safe tumor removal with minimal neurovascular injury, laying the foundation for excellent long-term functional prognosis in pituitary adenoma patients.