BACKGROUND

Central diabetes insipidus (CDI) is a common complication following transsphenoidal surgery for pituitary adenomas, but CDI as an initial presentation in pituitary adenomas is extremely rare. We report a case of a 67-year-old Filipino male with pituitary macroadenoma presenting as central diabetes insipidus, manifesting as a two-month history of severe frontotemporal headache, increased thirst, and polyuria, which was managed with desmopressin followed by transsphenoidal surgery. Three months postoperatively, the thyroid and adrenocorticotropic axis remained intact, and pituitary bright spot recovery was observed. He was clinically stable; hence, desmopressin was gradually tapered and discontinued. This case report presents a unique case of a pituitary adenoma that initially presented with central DI but later showed a complete resolution of symptoms along with the normalization of the "bright spot" seen on MRI, a hallmark of the posterior pituitary. Treatment options for preoperative CDI may include surgical or medical management, with some cases reported as self-limiting. However, the rarity of such cases underscores the urgent need for more clinical studies to fully understand the course of this condition. This case highlights a unique presentation of central diabetes insipidus in a pituitary macroadenoma and the possibility of complete resolution of symptoms coinciding with pituitary bright spot recovery post operatively.

Introduction: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an uncommon inflammatory demyelinating disorder of the central nervous system, with a reported prevalence of 1.3–2.5 per 100,000. Hypothalamic–pituitary involvement is rare and can mimic structural lesions, presenting with varying degrees of hypopituitarism and central diabetes insipidus. Case: A 30-year-old male presented with a 2-year history of poor concentration, blurring of vision and lethargy. Initial investigations revealed severe hypernatremia (serum sodium 165 mmol/L) and a 1.4 × 2.1 × 1.3 cm suprasellar cistern mass on CT scan, with differential diagnoses including meningioma and germinoma. Brain magnetic resonance imaging showed abnormal signals in the optic pathways and hypothalamus, raising suspicion of a demyelinating process. Endocrine evaluation confirmed panhypopituitarism: elevated prolactin (1125.2 mIU/L), hypogonadotropic hypogonadism (follicle-stimulating hormone 0.7 IU/L, LH 0.3 IU/L, testosterone <0.35 nmol/L), central hypothyroidism (TSH 3.8 mIU/L, free T4 5.88 pmol/L) and low cortisol (33.1 nmol/L). Persistent hypernatremia (up to 171 mmol/L) with high serum osmolality (370 mOsm/kg) and low urine osmolality (237 mOsm/kg) confirmed central diabetes insipidus, as urine osmolality rose to 755 mOsm/kg following intravenous desmopressin. He was commenced on sublingual desmopressin 60 micrograms twice daily, hydrocortisone (10 mg morning, 5 mg afternoon), levothyroxine 75 micrograms daily and monthly intramuscular testosterone 150 mg. Subsequent readmissions for generalized weakness and fever led to cerebrospinal fluid analysis and serum testing, which were positive for MOG antibodies and negative for aquaporin-4 antibodies, confirmed MOGAD. During a third admission with recurrent generalized weakness, he responded favorably to intravenous methylprednisolone (1 g daily for 5 days), followed by a tapering oral prednisolone regimen. Conclusion MOGAD can involve the hypothalamic–pituitary axis and mimic a suprasellar mass. In patients with panhypopituitarism, central diabetes insipidus and compatible imaging, inflammatory demyelination should be suspected. MOG antibody positivity and response to corticosteroids support diagnosis and guide management.
Diabetes Insipidus ; Hypopituitarism

Introduction: Immunoglobulin G4-related hypophysitis (IgG4-RH) is a rare fibro-inflammatory disorder affecting the pituitary gland. Glucocorticoids remain the first-line therapy, but their use may be complicated in patients with significant metabolic comorbidities. We report a case of suspected IgG4-RH presenting with hyperosmolar hyperglycemic state (HHS), highlighting the challenges of balancing disease control against glucocorticoid metabolic toxicity adverse effects. Case: A 32-year-old female with obesity and newly diagnosed diabetes mellitus was admitted with HHS. Prior to admission, she reported weight fluctuations, episodic headaches, progressive visual disturbance, and secondary amenorrhea. Following resolution of HHS, persistent polyuria of 10–16 L/day prompted further evaluation and led to a diagnosis of arginine vasopressin deficiency. Anterior pituitary hormonal work-up revealed hypogonadotropic hypogonadism. Pituitary magnetic resonance imaging demonstrated infundibular thickening measuring 0.5 cm, with concomitant marked bilateral parotid enlargement. Serum IgG4 was elevated at 2.26 g/L (0.63–2.01), raising strong suspicion for IgG4-RH with systemic involvement. Histopathological confirmation from the parotid gland biopsy was consistent with sialadenosis. She was commenced on sublingual desmopressin and cyclical sex hormone replacement therapy. Given the provisional diagnosis of IgG4-RH, oral prednisolone 40 mg daily was initiated as a reduced induction regimen. However, treatment was poorly tolerated, with rapid weight gain from 93 to 100 kg and worsening glycemic control. Prednisolone was therefore tapered rapidly to 10 mg daily. Repeat imaging demonstrated interval improvement in infundibular thickening, but no functional endocrine recovery was observed. Conclusion This case illustrates the therapeutic challenge of managing IgG4-RH in the setting of pre-existing metabolic syndrome. Although glucocorticoids are effective for induction, their metabolic adverse effects may significantly restrict treatment tolerability. Early consideration of steroidsparing agents, such as rituximab or azathioprine, may be important to achieve remission while minimizing glucocorticoid-related adverse effects.
Autoimmune Hypophysitis

Introduction: Pituitary macroadenomas may present with mass effects, hypopituitarism, or hormone hypersecretion. Hyperprolactinemia, resulting from a prolactin-secreting tumor or stalk compression, typically suppresses gonadotropins. Thus, elevated follicle-stimulating hormone (FSH) and luteinizing hormone (LH) with low testosterone in this context are unusual. We report a macroprolactinoma with a clinically non-functioning gonadotroph adenoma. Case: A 69-year-old male presented with acute giddiness and headache while in Vietnam. He reported reduced libido but no visual symptoms or galactorrhea. Examination showed no neurological deficits, normal visual fields, and secondary sexual characteristics; bilateral testes volume of 25 mL. Magnetic resonance imaging (MRI) brain revealed a 1.6 × 2.2 × 2.1 cm pituitary macroadenoma compressing the optic chiasm and pituitary stalk. Initial pituitary evaluation demonstrated hyperprolactinemia (prolactin >200 µg/L; normal 2.4–13.1), central hypothyroidism (T4 6.8 pmol/L [7.8–14.4], thyroid-stimulating hormone 2.3 mIU/L [0.38–5.3]), elevated FSH (21.5 IU/L [1.2–19.2]) and LH (191 IU/L [1.24–8.62]), low testosterone (8.88 nmol/L), normal insulin-like growth factor 1 (IGF-1) (68 µg/L [46.5–191.9]), and cortisol 237 nmol/L. Cabergoline was initiated at 0.25 mg twice weekly and titrated to 1 mg twice weekly over 4 months, alongside levothyroxine 25 µg daily. Repeated MRI brain 2 months after cabergoline initiation showed a persistent macroadenoma (1.7 × 2.2 × 2.2 cm) with bilateral cavernous sinus extension. Prolactin decreased to <170 µg/L, central hypothyroidism persisted; levothyroxine was optimized, and hydrocortisone was initiated. At the 5-month follow-up, prolactin further improved to 57 µg/L. Central hypothyroidism and borderline adrenal function persisted, requiring continued replacement therapy. Testosterone remained low-normal (10.2 nmol/L) despite elevated FSH (15.4 IU/L) and LH (92 IU/L). Followup MRI and hormonal reassessment were planned in May 2026. Conclusion Profoundly elevated prolactin level >200 µg/L and response to cabergoline reflect true prolactinoma rather than stalk effect. Persistently low testosterone with discordant high FSH/LH suggests a non-functioning gonadotroph component producing biologically inactive gonadotropins. Definitive diagnosis requires histopathological confirmation, while serial biochemical and radiological follow-up guides management and clarifies tumor subtype.
Gonadotrophs ; Hyperprolactinemia

Introduction: Gender-affirming hormone therapy (GAHT) for transgender women utilizes estrogen and an anti-androgen like cyproterone acetate (CPA) which can both lead to hyperprolactinemia. Although mild prolactin elevations are common, the development of prolactinomas in transgender women on GAHT is rare. Case: A 23-year-old trans-woman on self-purchased estradiol hemihydrate (17β-estradiol) 4 mg and CPA 12.5 mg daily for GAHT presented with galactorrhea. Investigations revealed markedly elevated prolactin at 2,369 mIU/L and elevated estradiol at 848 pmol/L. A pituitary magnetic resonance imaging (MRI) identified a 0.4 × 0.5 cm microprolactinoma. She declined clinical advice to reduce her medication dose and continued on the same treatment. In the subsequent year, her peak prolactin was 1,383 mIU/L, and a repeat MRI showed the microprolactinoma remained stable. She continues to be on close clinical monitoring. Transgender females experience approximately a fourfold higher rate of developing prolactinomas. The patient’s choice to persist with GAHT reflects the challenges in managing gender dysphoria alongside medical complications. A recent paper by BJ Nolan et al. suggests using prolactin levels exceeding 2,000–3,000 mIU/L to guide further investigations including a pituitary MRI to rule out a prolactinoma. In most cases, the serum prolactin levels will return to the normal range with a reduction or discontinuation of the GAHT. Normalization of prolactin levels have been reported after gonadectomy and CPA cessation in transgender females on GAHT, which suggests that CPA usage may be associated with higher risk of hyperprolactinemia compared to estrogen therapy. Conclusion This case highlights that GAHT can lead to development of prolactinomas. Prolactin monitoring and MRI investigations should be reserved for symptomatic patients, and for those with significantly elevated or increasing prolactin levels. While treatment using dopamine agonists have been reported, this case demonstrates that conservative management and close monitoring can be a viable approach for structurally stable microprolactinomas.
Female ; Prolactinoma ; Transgender Persons

Introduction: Prolactinomas are the most common functioning pituitary adenomas, accounting for 50% of all pituitary tumors. Microprolactinomas (<10 mm) are the most frequent subtype and usually follow a benign course, with tumor progression reported in only 5% of cases. We report a rare case of microprolactinoma that progressed to macroprolactinoma over 16 years. : A 39-year-old female was initially diagnosed with a microprolactinoma at the age of 23 during evaluation for irregular menses since menarche. Baseline pituitary magnetic resonance imaging (MRI) at that time revealed a lesion measuring 2 × 2 × 0.8 mm. She was treated with bromocriptine for 2 months but subsequently lost to followup. The patient had been married for 10 years without conceiving and continued to have irregular menses. She decided to repeat prolactin before seeking fertility treatment after 16 years. Laboratory investigations revealed markedly elevated serum prolactin (>42,000 mIU/L) with suppressed gonadotropins, while thyroid and adrenal axes were normal. She reported no galactorrhea, headache, or visual disturbances and notably did not develop amenorrhea. Visual field assessment was normal. Repeat pituitary MRI demonstrated that the previously diagnosed microprolactinoma had progressed to a macroprolactinoma, measuring 2.1 × 2.3 × 1.6 cm, with extension into the left cavernous sinus and encasement of the left internal carotid artery, without optic chiasm compression. Oral cabergoline 0.25 mg twice weekly was initiated. She was counselled regarding potential risks of dopamine agonist therapy and advised to use mechanical contraception during treatment. At the 2-week follow-up, she tolerated therapy well. Follow-up imaging and prolactin monitoring were planned at 3 months to assess treatment response and guide fertility planning. Conclusion This case highlights the rare progression of microprolactinoma to macroprolactinoma, underscoring the importance of long-term monitoring in patients with prolactinoma. A careful balance between tumor control and fertility management is essential for optimizing care in women of reproductive age.
Prolactinoma

Introduction: Giant prolactinomas represent 2–3% of prolactin-secreting pituitary adenomas and show a male predominance. They present with mass effect symptoms and hypogonadism, but may be overlooked, leading to delayed diagnosis. Although dopamine agonists are first-line therapy, management remains challenging due to the large size and invasive behavior. This study aims to describe the clinical and radiological features, treatment modalities, and outcomes of three cases of giant prolactinomas. We retrospectively reviewed three men with giant prolactinomas, including their clinical, biochemical, and radiological features, along with treatment and outcomes. Cases: Three male patients aged 35–59 years with giant prolactinomas were included. Two patients presented with visual disturbances, headache, and features of hypogonadism, while one patient had acute confusion and visual loss secondary to obstructive hydrocephalus requiring ventriculoperitoneal shunt insertion. Imaging in all cases demonstrated large invasive pituitary macroadenomas with extensive local extension. Baseline serum prolactin levels were markedly elevated, ranging from 86,568 to 441,116 uIU/mL (86–324 uIU/mL). All patients had secondary hypogonadism, while secondary hypothyroidism and hypocortisolism were each identified in two patients. One patient also had poorly controlled diabetes mellitus at presentation. Dopamine agonist therapy was initiated as the primary therapy for all the patients. Two patients developed cerebrospinal fluid leak following initiation of low-dose dopamine agonist therapy (one patient received cabergoline 0.25 mg weekly, while another received 0.5 mg weekly), which resolved spontaneously with conservative management. Serum prolactin levels decreased markedly, with significant improvement in symptoms related to mass effect following treatment. Conclusion Giant prolactinomas may present with significant mass effect and multiple pituitary hormone deficiencies. Dopamine agonists remain the cornerstone of management and can result in substantial biochemical and clinical improvement even in large invasive tumors. However, rapid tumor shrinkage may lead to complications such as cerebrospinal fluid leak, highlighting the importance of close monitoring during treatment initiation.
Prolactinoma

Introduction: Polycystic ovary syndrome (PCOS) is the most common cause of hyperandrogenism in women of reproductive age. However, several endocrine disorders, particularly Cushing disease (CD), can closely mimic the clinical, biochemical, and radiological features of PCOS. This overlap may lead to misdiagnosis and delayed recognition of hypercortisolism, with significant metabolic and reproductive consequences. Case: We report a 24-year-old female with young-onset diabetes mellitus who was referred for endocrine co-management during admission for recurrent mons pubis and labial abscesses with poorly controlled glycemia. She had a 5-year history of progressive hirsutism, oligomenorrhoea, scalp hair loss, significant weight gain, and insulin resistance, and had previously been labelled as having PCOS during adolescence, with subsequent default of follow-up. On examination, she was obese (body mass index 33 kg/ m²) with plethoric facies, acanthosis nigricans, proximal myopathy, and hirsutism (Ferriman–Gallwey score 10), without overt virilization or acromegalic features. Biochemical evaluation demonstrated severe hyperandrogenism with markedly elevated total testosterone (7.05 nmol/L), suppressed gonadotropins, and adrenocorticotropic hormone (ACTH)-dependent hypercortisolism. Cortisol failed to suppress on low-dose dexamethasone testing, and 24-hour urinary free cortisol was markedly elevated (>4,900 nmol/24 h). Pelvic ultrasonography and computed tomography imaging showed polycystic ovarian morphology without evidence of an ovarian mass. Pituitary magnetic resonance imaging revealed a small right-sided pituitary microadenoma measuring 2.6 × 3.7 mm. Inferior petrosal sinus sampling demonstrated a central-to-peripheral ACTH gradient with adequate prolactin ratios, confirming pituitary CD. Conclusion This case highlights how Cushing disease can closely mimic PCOS, including polycystic ovarian morphology and hyperandrogenism. Progressive symptoms, severe biochemical androgen excess, and marked insulin resistance should prompt evaluation for secondary causes of hyperandrogenism, particularly hypercortisolism, to avoid delayed diagnosis and prolonged morbidity.
Female ; Hyperandrogenism ; Pituitary ACTH Hypersecretion ; Polycystic Ovary Syndrome

Introduction: Nonfunctioning pituitary adenomas (NFPA) may cause central hypothyroidism due to pituitary compression, often presenting with low thyroid-stimulating hormone (TSH). However, suppressed TSH in this setting should not automatically be attributed to pituitary dysfunction, as primary hyperthyroidism—such as Graves’ disease—may rarely coexist. Distinguishing between these disorders is essential to avoid misdiagnosis and inappropriate management. Case: A 42-year-old female presented with intermittent headache, visual field impairment, palpitations, fine tremors, and weight loss. Physical examination revealed visual field deficits and no goiter. Laboratory evaluation showed cortisol level of 1 µg/dL (normal: 3.7–19.4 µg/dL), luteinizing hormone 1.62 mU/L (normal: 2.4–12.6 mU/L), follicle-stimulating hormone 5.01 mU/L (normal: 3.5–12.5 mU/L), free thyroxine 4 28.32 pmol/L (normal: 12–22 pmol/L), TSH 0.02 µIU/mL (normal: 0.27–4.2 µIU/mL), and prolactin 70.84 ng/mL. Thyrotropin receptor antibody (TRAb) was 3.53 IU/L, confirming Graves’ disease. Contrast-enhanced brain magnetic resonance imaging demonstrated a pituitary macroadenoma (2.13 × 2.28 × 3.05 cm) with optic chiasm compression. The patient was diagnosed with NFPA, Graves’ disease, secondary adrenal insufficiency, possible hypogonadotropic hypogonadism, and hyperprolactinemia likely due to the stalk effect. Preoperative management included hydrocortisone replacement and antithyroid therapy. The patient subsequently underwent transsphenoidal surgery with appropriate perioperative care. Postoperatively, no new pituitary hormone deficiencies were observed. She was maintained on thiamazole 10 mg daily with clinical improvement and remains under regular follow-up. Conclusion This case highlights a rare but clinically important coexistence of NFPA and Graves’ disease. Suppressed TSH in patients with pituitary adenoma should not be assumed to reflect pituitary dysfunction without thorough evaluation. Comprehensive thyroid assessment is crucial to ensure accurate diagnosis and appropriate management.
Pituitary Neoplasms ; Graves Disease

Introduction: Discordant thyroid function tests (TFTs), characterized by elevated free thyroxine 4 (FT4) with non-suppressed thyroid-stimulating hormone (TSH), pose a significant diagnostic challenge. Differentiating between Resistance to Thyroid Hormone (RTH) and TSH-secreting pituitary adenoma (TSH-oma) is essential, as management strategies differ substantially. Case: A female with a history of hyperthyroidism diagnosed in 2011 was treated with antithyroid drugs for 1 year before defaulting on follow-up. She was later found to have discordant TFTs at a private centre, where a brain computed tomography scan was reportedly normal. She was referred to our centre for optimization of thyroid function prior to planned thyroidectomy for a solitary large right thyroid nodule measuring 4.2 × 2.8 × 4.7 cm. Fine-needle aspiration cytology demonstrated a benign follicular lesion (Bethesda II). Despite restarting antithyroid medication, she remained clinically euthyroid with no overt thyrotoxic symptoms apart from intermittent palpitations without documented tachycardia. Antithyroid therapy was discontinued. Serial TFTs across multiple assay platforms consistently demonstrated elevated FT4 with inappropriately normal TSH levels. Thyroid autoantibodies, including TSH receptor and anti-thyroid peroxidase antibodies, were negative. Pituitary magnetic resonance imaging showed no evidence of adenoma, and serum α-subunit level was normal (0.3 ng/ mL), making TSH-oma unlikely. Dynamic testing was not performed as thyrotropin-releasing hormone stimulation was unavailable at our centre, while T3 suppression testing was deemed inappropriate due to symptomatic palpitations. Family screening was not possible as the patient was not in contact with her relatives. In the absence of pituitary pathology and given her largely euthyroid clinical status, RTH was considered the most likely diagnosis. Conclusion This case highlights the importance of considering RTH in patients with persistent discordant TFTs, particularly when clinical findings do not correlate with biochemical abnormalities. Early recognition and appropriate pituitary evaluation are essential to prevent misdiagnosis and avoid unnecessary antithyroid therapy or thyroidectomy.
Pituitary Neoplasms ; Thyroid Hormones ; Thyrotropin