Endocrine

A 34-year-old man presents with a sudden-onset severe headache, nausea, and visual disturbances including diplopia and tunnel vision. He reports increasing fatigue and reduced libido over the past 6 months. Examination reveals bitemporal hemianopia and left ptosis. Serum labs show markedly elevated prolactin (2100 mIU/L), low testosterone, and borderline hyponatremia. Pituitary MRI reveals a 2.5 cm sellar/suprasellar mass with optic chiasm compression, cavernous sinus invasion, and slight extension into the third ventricle. What is the most immediately threatened structure, and what is the best initial management strategy?

A 45-year-old female presents with a three-month history of fatigue, weight gain, and constipation. On examination, she has a low-grade fever, bradycardia, and her skin feels cold and doughy with non-pitting oedema, most notably around her eyes and in her hands. Her ECG shows low voltage QRS complexes and her initial blood work reveals a hypochromic microcytic anaemia. She is currently on no medication besides an iron supplement, which has not improved her anaemia.

Given this patient's clinical picture, which of the following is the most likely diagnosis?

A 35-year-old male presents with sudden onset of severe, crushing chest pain radiating to his back, diaphoresis, and profound hypotension (BP 70/40 mmHg). He has a known history of uncontrolled hypertension and visual field defects, for which he has been intermittently followed. On examination, he has a wide pulse pressure and a new diastolic murmur. Laboratory investigations are pending. Given his history, what is the most critical immediate concern regarding the anatomical integrity of a major endocrine gland, and what is the most likely life-threatening complication?

A 14-year-old female presents with recent onset polyuria, polydipsia, and significant weight loss. Her random blood glucose is $320$ mg/dL ($17.8$ mmol/L), and HbA1c is $10.5\%$. Surprisingly, her C-peptide levels are detectable and within the normal range for a non-diabetic individual. She denies family history of Type 1 Diabetes, and islet autoantibodies are negative. Which specific genetic mutation, affecting an enzyme involved in glucose metabolism, is the most likely underlying cause of her diabetes phenotype?

A 70-year-old male with Type 2 Diabetes Mellitus presents to the emergency department with a 3-day history of profound weakness, confusion, and lethargy. His wife reports he has been drinking very little water and urinating excessively. On examination, he is severely dehydrated, disoriented, and has a blood pressure of $90/60$ mmHg. Point-of-care glucose is $>600$ mg/dL ($>33.3$ mmol/L). Serum osmolality is $345$ mOsm/kg, and there are no ketones in his urine or blood. Which specific hypothalamic osmoreceptor dysfunction, combined with severe hyperglycemia, is critical to the development of this patient's acute metabolic emergency?

A 48-year-old female presents with persistent, severe hypertension refractory to triple-drug therapy, along with episodes of palpitations, sweating, and anxiety. Her blood pressure is consistently above 180/100 mmHg. She reports no family history of similar conditions. Twenty-four-hour urine metanephrines are significantly elevated. A CT abdomen reveals a 4 cm left adrenal mass.

Prior to surgical resection, what is the most crucial pharmacological intervention to prevent a life-threatening complication during surgery, and what specific anatomical structure is this intervention primarily aiming to protect from an acute surge of neurohumoral substances?

A 34-year-old female presents to the ICU with a temperature of 40.5°C, heart rate of 160 bpm, severe agitation, and delirium. She has a history of a diffuse goiter and was recently treated for a urinary tract infection with trimethoprim-sulfamethoxazole. On examination, she has lid lag and a fine tremor.

Which medication, by directly inhibiting the peripheral conversion of T4 to the more active T3, is a critical component of the initial management of her condition?

A 32-year-old female presents with secondary amenorrhea, galactorrhea, and headaches. Her prolactin level is significantly elevated at 2500 mIU/L (normal range <500 mIU/L). An MRI of the pituitary gland reveals a 1.2 cm adenoma. She expresses a desire for future fertility.

Which pharmacological agent is the most appropriate first-line treatment for this patient, and what is its primary mechanism of action leading to therapeutic effect?

A 45-year-old male with a known history of a non-functioning pituitary macroadenoma presents to the emergency department with a sudden, severe 'thunderclap' headache, diplopia, and rapidly deteriorating consciousness. On examination, his blood pressure is 80/50 mmHg, and he has bilateral ptosis and ophthalmoplegia. An urgent CT scan confirms hemorrhage into the pre-existing sellar mass.

What is the most critical immediate intervention required to prevent mortality in this patient?

A 68-year-old female with a history of osteoporosis and poorly controlled Type 2 Diabetes Mellitus undergoes an abdominal CT for unrelated reasons, which reveals a 2.5 cm lipid-poor adrenal adenoma. She denies classic Cushingoid features like striae or a dorsal fat pad. Her blood pressure is 150/90 mmHg.

Which diagnostic test is most sensitive for detecting autonomous cortisol secretion in this patient with a suspected subclinical Cushing's syndrome?

A 29‑year‑old woman with known type 1 diabetes on a basal‑bolus regimen reports sudden onset galactorrhoea, amenorrhoea, and headaches for 3 months. Her prolactin is 250 ng/mL (normal <20), TSH normal, and MRI pituitary shows a 1.5 cm sellar mass compressing the optic chiasm.

Which is the most appropriate next step?

A 35-year-old man with newly diagnosed type 1 diabetes presents with a 3‑month history of worsening fatigue, unintentional weight loss, and recurrent postural dizziness. He notes that his insulin requirements have paradoxically decreased since diagnosis. On examination, he is orthostatic (sitting BP 125/80 mmHg, standing BP 90/60 mmHg) and has diffuse hyperpigmentation most pronounced on his palmar creases and buccal mucosa. Laboratory studies show:

• Na⁺ 122 mmol/L (normal 135–145)

• K⁺ 5.8 mmol/L (normal 3.5–5.0)

• Morning serum cortisol 90 nmol/L (normal 140–690)

• Plasma ACTH > 2,000 pg/mL (normal 15–60)

Which of the following is the most likely diagnosis?

A 50-year-old female is evaluated for refractory hypertension and persistent hypokalemia (3.1 mmol/L) despite potassium supplementation. Her plasma aldosterone concentration (PAC) is elevated at 25 ng/dL, and her plasma renin activity (PRA) is suppressed at 0.2 ng/mL/hr. An adrenal CT scan reveals a 1.5 cm left adrenal adenoma and a normal-appearing right adrenal gland. What is the most appropriate next step to confirm the source of aldosterone excess before proceeding to surgery?