Endocrinology

A 58-year-old man with long-standing type 2 diabetes presents with polyuria, polydipsia, and confusion after a week of bronchitis treated with high-dose prednisone. Vitals: BP 100/60 mmHg, HR 112/min, dry mucous membranes. Labs: glucose 980 mg/dL, Na 152 mEq/L (corrected 166), K 4.1 mEq/L, bicarbonate 22 mEq/L, serum osmolality 340 mOsm/kg, pH 7.36, ketones trace.

A 24-year-old woman with T1DM uses a pump and presents with abdominal pain, nausea, Kussmaul respirations, and fruity breath after a kinked infusion set overnight. Vitals: HR 118/min; BP 108/64 mmHg. Labs: glucose 380 mg/dL, pH 7.21, HCO₃⁻ 12 mEq/L, anion gap 22, β-hydroxybutyrate elevated, K 5.2 mEq/L.

A 66-year-old man with resistant hypertension on amlodipine, HCTZ, and lisinopril has muscle weakness and nocturnal leg cramps. Labs: K 2.9 mEq/L, Na 144 mEq/L, metabolic alkalosis, morning aldosterone 26 ng/dL with suppressed renin. Adrenal CT shows a 1.6 cm right adrenal nodule.

A 37-year-old woman reports palpitations, heat intolerance, and weight loss. Exam: fine tremor, brisk reflexes, and a diffusely enlarged, non-nodular thyroid with bruit. Labs: suppressed TSH, elevated free T4/T3; positive TSI. Radioiodine uptake is high and diffuse.

A 70-year-old woman with chronic kidney disease presents with bone pain, pruritus, and muscle weakness. Labs: Ca 8.1 mg/dL, phosphate 6.2 mg/dL, PTH markedly elevated, 25(OH)D low; X-rays show subperiosteal bone resorption.

A 29-year-old woman has fatigue, weight gain, constipation, and menorrhagia 8 months postpartum. Exam: dry skin, delayed reflex relaxation. Labs: TSH 12 mIU/L, free T4 low; thyroid peroxidase antibodies positive.

A 54-year-old man with pituitary macroadenoma presents with coarse facial features, enlarged hands, oily skin, and new-onset diabetes. IGF-1 is elevated; oral glucose tolerance test fails to suppress GH. MRI: 1.8 cm sellar mass without optic chiasm compression.

A 47-year-old woman with depression and weight gain has easy bruising, proximal muscle weakness, and purple striae. Labs: fasting glucose 160 mg/dL, 1 mg overnight dex suppression test abnormal; ACTH elevated; MRI pituitary normal; CT shows no adrenal mass. High-dose dexamethasone suppresses cortisol.

A 32-year-old woman has primary infertility, oligomenorrhea, hirsutism, and BMI 31. Labs: LH:FSH ratio 3:1, total testosterone mildly elevated, TSH normal, prolactin normal; fasting insulin high. Pelvic ultrasound shows enlarged ovaries with multiple peripheral follicles.

A 59-year-old man with hypertension and episodic headaches, palpitations, and diaphoresis has paroxysmal BP 210/110 mmHg. Plasma free metanephrines elevated; MRI reveals a 3.2 cm left adrenal mass.

A 72-year-old woman fractures her wrist after a ground-level fall. DEXA: T-score −2.8 at femoral neck. Labs: Ca 9.4 mg/dL, 25(OH)D 18 ng/mL, creatinine normal.

A 63-year-old man has bone pain in the pelvis and skull, increased hat size, and hearing loss. Labs: markedly elevated ALP; Ca and phosphate normal. Bone scan shows increased uptake in affected areas.

A 28-year-old man with polyuria and polydipsia voids >7 L/day. Serum Na 150 mEq/L, low urine osmolality despite water deprivation; desmopressin increases urine osmolality by 70%.

A 45-year-old woman with fatigue and hyperpigmentation presents with hypotension and salt craving after a GI illness. Labs: Na 128 mEq/L, K 5.8 mEq/L, low morning cortisol, high ACTH; cosyntropin test shows inadequate cortisol rise.

A 38-year-old man with severe hypothyroidism (TSH 42, free T4 very low) presents with fatigue and weight gain. Screening shows LDL 190 mg/dL and triglycerides 180 mg/dL.

A 26-year-old woman has painless thyroid enlargement and transient thyrotoxicosis 3 months after COVID-19. ESR elevated; radioiodine uptake low.

A 60-year-old man with weight loss and depression has hypercalcemia (Ca 12.2 mg/dL), low PTH, normal vitamin D, and a lytic lesion on skull X-ray.

A 34-year-old man with refractory peptic ulcers and nephrolithiasis has Ca 11.3 mg/dL, PTH high-normal, and a pituitary microadenoma. Family history positive for pancreatic tumors.

A 48-year-old woman with bipolar disorder on lithium presents with polyuria and hypernatremia. Water deprivation fails to concentrate urine; desmopressin produces minimal change.

A 39-year-old man presents with gynecomastia, decreased libido, and headaches. Prolactin is 145 ng/mL; TSH normal; MRI shows a 9 mm pituitary lesion.

A 51-year-old woman with a 2.5 cm nonfunctioning adrenal incidentaloma discovered on CT for renal colic. She is normotensive and asymptomatic. Overnight dex suppression test shows cortisol 2.3 µg/dL (abnormal).

A 55-year-old postmenopausal woman on aromatase inhibitor therapy for breast cancer has T-score −2.6 and vertebral compression fracture.

A 30-year-old woman has fatigue, constipation, and carpal spasms. Labs: Ca 7.2 mg/dL, phosphate 5.6 mg/dL, PTH low. Chvostek and Trousseau signs present; QTc prolonged.

A 41-year-old man complains of fatigue and weight gain. Labs show TSH 0.2 mIU/L with free T4 low; morning cortisol normal; MRI reveals a 1.5 cm pituitary macroadenoma compressing the stalk.

A 69-year-old man with longstanding diabetes presents with painful acute swelling and erythema of the great toe; uric acid 9.0 mg/dL. HbA1c is 9.2%. He requests steroids for gout flares.

A 52-year-old woman with mild hypercalcemia (Ca 10.9 mg/dL), PTH high-normal, and nephrolithiasis; DEXA T-score −1.8. 24-h urine calcium excretion is elevated.

A 33-year-old postpartum woman has anxiety, palpitations, and weight loss 2 months after delivery; TSH suppressed, free T4 high. Radioiodine uptake is very low; TPO antibodies present.

A 46-year-old man with hypertension develops episodic weakness after carbohydrate-heavy meals. Labs during attack: K 2.6 mEq/L, TSH low, free T4 high.

A 71-year-old woman with type 2 diabetes and CKD stage 3 has A1c 8.4% on metformin 1000 mg BID. eGFR 42 mL/min/1.73 m², albumin/creatinine ratio 300 mg/g, BP 132/78 on ACE inhibitor.

A 62-year-old man with long-standing diabetes presents with orthostatic hypotension, erectile dysfunction, and gastroparesis symptoms. Cardiac workup is negative.

A 58-year-old man has a 3.1 cm thyroid nodule discovered incidentally. TSH normal. Ultrasound reveals solid hypoechoic nodule with irregular margins and microcalcifications; no suspicious nodes.

A 44-year-old woman with amenorrhea, galactorrhea, and headaches has prolactin 98 ng/mL; pregnancy negative; TSH normal. MRI shows 4 mm microadenoma.

A 36-year-old woman undergoes total thyroidectomy for papillary carcinoma. One day later, she has perioral tingling and carpal spasm. Labs: Ca 7.0 mg/dL, PTH low.

A 48-year-old woman has persistent hypertension and episodes of muscle weakness. Labs: K 3.1 mEq/L. ARR positive; saline suppression fails to suppress aldosterone. CT shows bilateral micronodular adrenal hyperplasia.

A 61-year-old woman with poorly controlled T2DM (A1c 9.1%) and ASCVD has BMI 33, on metformin and high-intensity statin. eGFR 76.

A 42-year-old man with recurrent nephrolithiasis and bone loss has Ca 11.0 mg/dL, phosphate low, PTH elevated, 24-h urine calcium high. Neck ultrasound suggests single adenoma.

A 69-year-old man with hypotension, hyponatremia, and hyperkalemia after stopping chronic prednisone abruptly. Morning cortisol low with low ACTH; cosyntropin test is blunted.

A 31-year-old man presents with severe headache, diaphoresis, and palpitations during anesthesia induction for elective surgery; BP spikes to 260/140 mmHg. He had episodes at home but no workup.

A 57-year-old woman with fatigue and mild weight gain has TSH 6.8 mIU/L, free T4 normal, TPO positive. She reports infertility planning.

A 50-year-old man with nail changes and scalp psoriasis has fasting glucose 104 mg/dL, A1c 6.3%, triglycerides 320 mg/dL, HDL 36 mg/dL. BMI 31, BP 138/86.

A 64-year-old woman on prolonged glucocorticoids for polymyalgia rheumatica presents with atraumatic vertebral compression fracture. 25(OH)D is 22 ng/mL.

A 45-year-old woman with recurrent kidney stones has Ca 9.3 mg/dL, PTH normal, 25(OH)D 10 ng/mL, urine Ca elevated, and low citrate.

A 59-year-old man has flushing, diarrhea, and wheezing. 5-HIAA is elevated; CT shows a 2.2 cm ileal mass with liver lesions.

A 34-year-old man with headaches and visual field cuts has serum sodium 126 mEq/L, serum osmolality low, urine osmolality 580 mOsm/kg. MRI shows a large sellar mass compressing the stalk.

A 52-year-old woman with medullary thyroid carcinoma had total thyroidectomy; calcitonin remains elevated and she has episodic headaches and hypertension.

A 29-year-old man with celiac disease is started on high-dose vitamin D/calcium. One week later he develops polyuria and constipation; Ca 12.4 mg/dL, PTH suppressed; 25(OH)D 80 ng/mL, 1,25(OH)₂D normal.

A 62-year-old man with over-replaced levothyroxine has palpitations; ECG shows atrial fibrillation. TSH <0.01, free T4 high.

A 36-year-old woman presents with fractures after minimal trauma and blue sclerae since childhood; hearing loss emerged in her 20s.

A 55-year-old man has fasting glucose 122 mg/dL and A1c 6.1%. He had a prior MI and wants to avoid diabetes. BMI 29.

A 68-year-old man with hypothyroidism on levothyroxine starts calcium carbonate and ferrous sulfate; 8 weeks later TSH rises to 9.8 mIU/L.

A 46-year-old woman with flushing and diarrhea has new hyperthyroidism; TSH suppressed, free T4 high; radioiodine uptake is low. She takes weight-loss supplements. Thyroglobulin is low.

A 41-year-old man with pituitary macroadenoma has bitemporal hemianopsia and low morning testosterone with low LH/FSH; other axes intact.

A 72-year-old woman with T2DM, CAD, and CKD (eGFR 34) presents with heart failure with EF preserved. A1c 7.8% on metformin 500 mg BID.

A 58-year-old woman with fatigue and cold intolerance is on amiodarone. Labs: TSH 7.2 mIU/L, free T4 normal, TPO negative.

A 39-year-old woman with hirsutism, acne, and menstrual irregularity has total testosterone moderately elevated, DHEA-S normal, 17-OHP normal; pelvic ultrasound shows a unilateral 3 cm ovarian stromal mass.

A 67-year-old man with unintentional weight loss and diarrhea has glucose 62 mg/dL during episodes of diaphoresis and confusion; C-peptide elevated; sulfonylurea screen negative; 72-hour fast confirms endogenous hyperinsulinism.

A 52-year-old man with multinodular goiter has subclinical hyperthyroidism (TSH 0.07, normal free T4/T3) and atrial fibrillation.

A 48-year-old woman with chronic pancreatitis develops brittle diabetes with frequent hypoglycemia and steatorrhea.

A 37-year-old man presents with pathologic fractures and proximal muscle weakness. Labs: phosphate 1.6 mg/dL (low), FGF23 high, normal calcium, low/normal PTH. Urine phosphate high. MRI identifies a small mesenchymal tumor in the thigh.

A 73-year-old man with severe hypertriglyceridemia (TG 980 mg/dL) presents with epigastric pain; lipase 920 U/L; ultrasound shows no gallstones; alcohol negative.

A 65-year-old woman with long-standing type 2 diabetes on basal–bolus insulin and an SGLT2 inhibitor presents with abdominal pain, nausea, and tachypnea after a colonoscopy prep. Glucose is 198 mg/dL, pH 7.24, HCO₃⁻ 14 mEq/L, anion gap 20, β-hydroxybutyrate elevated.

A 29-year-old G2P1 at 26 weeks has abnormal 75-g OGTT (fasting 100, 1 h 198, 2 h 171 mg/dL). She has BMI 32 and prior macrosomic infant.

A 58-year-old man with diabetes has a plantar ulcer probing to bone and low-grade fever. ESR 88 mm/h, CRP elevated; plain X-ray equivocal.

A 45-year-old woman with hypertension and albuminuric diabetic kidney disease (UACR 420 mg/g) on ACE inhibitor and SGLT2 asks about additional renal protection. eGFR 56.

A 42-year-old woman with BMI 38 and T2DM (A1c 8.1%) on metformin seeks weight loss aid; she has ASCVD risk factors and NAFLD.

A 51-year-old man (BMI 44) with T2DM (A1c 9.2%), OSA, and hypertension fails medical therapy for weight loss.

A 63-year-old man on warfarin develops sudden severe headache, ophthalmoplegia, and hypotension. He has a known nonfunctioning pituitary macroadenoma.

A 73-year-old woman is brought in in winter with hypothermia, bradycardia, hypotension, and hypoventilation. Exam: puffy face, dry skin. Labs: TSH 62, free T4 undetectable, Na 124.

A 34-year-old woman with Graves disease presents with fever, agitation, tremor, atrial fibrillation, and diarrhea after an infection.

A 67-year-old woman with multinodular goiter and subclinical hyperthyroidism (TSH 0.05) has atrial fibrillation and low BMD.

A 28-year-old postpartum woman 8 months after delivery has fatigue, agalactia, amenorrhea, cold intolerance, and hypotension after a hemorrhagic delivery.

A 36-year-old man on risperidone develops galactorrhea and low libido; prolactin 68 ng/mL; MRI normal.

A 55-year-old man has bilateral hard, non-tender gynecomastia and decreased libido. Labs: total testosterone low, LH/FSH high, estradiol normal, karyotype 47,XXY.

A 39-year-old woman has resistant hypertension and episodic headaches; plasma free metanephrines are borderline but 24-h urinary fractionated metanephrines are markedly elevated. CT is negative.

A 16-day-old male infant presents with vomiting, dehydration, hypotension, and ambiguous genitalia. Labs: Na 126, K 6.8, glucose low; 17-hydroxyprogesterone markedly elevated.

A 27-year-old woman has hirsutism, irregular menses, and infertility. 17-hydroxyprogesterone is elevated after ACTH stimulation; DHEA-S and testosterone mildly elevated.

A 64-year-old man with resistant hypertension and abrupt-onset hypokalemia has suppressed renin and elevated aldosterone. CT shows a 1.3 cm left adrenal nodule. AVS lateralizes to left.

A 59-year-old woman with central obesity, bruising, proximal myopathy, and hypertension has two abnormal late-night salivary cortisol tests. Low-dose dex suppression is abnormal; ACTH is suppressed. Adrenal CT shows a 3.5 cm heterogeneous mass.

A 41-year-old woman after parathyroidectomy for primary hyperparathyroidism develops prolonged hypocalcemia requiring high-dose calcium and calcitriol. Phosphate low, ALP high; bone pain.

A 72-year-old man with prolonged immobilization after hip fracture has calcium 11.8 mg/dL, PTH suppressed, normal PTHrP, vitamin D normal.

A 66-year-old woman with osteoporosis (T-score −3.1 and recent hip fracture) failed oral bisphosphonates due to GI intolerance.

A 39-year-old man presents with mild hypercalcemia (10.8 mg/dL), normal-high PTH, and low 24-h urine calcium excretion with Ca/Cr clearance ratio <0.01.

A 58-year-old woman on oral bisphosphonates for 8 years presents with exposed jaw bone after a dental extraction.

A 44-year-old man on high-dose prednisone for vasculitis has fasting glucose 220 mg/dL and postprandial peaks >300 mg/dL.

A 37-year-old woman with known thyroid eye disease has progressive diplopia and proptosis but is biochemically euthyroid on methimazole. She does not smoke.

A 63-year-old woman with T2DM and CKD has recurrent severe hypoglycemia on glyburide. eGFR 32 mL/min/1.73 m².

A 47-year-old man with incidental 2.2 cm adrenal mass has unenhanced CT 18 HU (lipid-poor). Work-up: normal metanephrines, ARR normal, abnormal dexamethasone suppression test (cortisol 2.1 µg/dL).

A 35-year-old woman with long QT syndrome has TSH 0.03 mIU/L, free T4 mildly high after starting amiodarone. Radioiodine uptake very low; thyroid antibodies negative.

A 57-year-old woman with recurrent kidney stones has Ca 10.7 mg/dL, PTH 76 pg/mL (high), 25(OH)D 12 ng/mL.

A 69-year-old man with long-standing T2DM is scheduled for elective surgery. He uses basal insulin glargine at night and prandial lispro.

A 33-year-old woman with infertility has normal FSH/LH, low morning progesterone in mid-luteal phase, and evidence of anovulation on tracking; BMI 22, no hirsutism. Prolactin, TSH normal.

A 61-year-old woman presents with muscle cramps and paresthesias after starting a loop diuretic. Labs: Mg 1.1 mg/dL (low), Ca 7.8 mg/dL, PTH normal.

A 48-year-old man treated for acromegaly by surgery still has elevated IGF-1; MRI shows residual 5 mm adenoma.

A 74-year-old woman with fragility hip fracture has eGFR 22 mL/min/1.73 m² and corrected Ca 9.1 mg/dL.

A 52-year-old man complains of flushing and refractory peptic ulcers. Gastrin high with very low gastric pH; PTH elevated, calcium 11.4 mg/dL; prolactin mildly high.

A 62-year-old woman on chronic opioids for back pain has fatigue, low libido, and morning cortisol 3 µg/dL; ACTH low.

A 38-year-old competitive cyclist has persistently low testosterone, low LH/FSH, low estradiol, and low leptin. BMI 19; DEXA shows low BMD.

A 70-year-old man with poorly controlled diabetes has progressive albuminuria despite ACE inhibitor and SGLT2; potassium 4.7, eGFR 48. BP well controlled.

A 31-year-old woman has a 1.1 cm hypoechoic thyroid nodule with microcalcifications; TSH normal; FNA shows Bethesda V (suspicious for malignancy).

A 66-year-old man with T2DM has A1c 9.8% despite metformin and GLP-1 RA. He refuses multiple daily injections.

A 47-year-old woman presents with severe hypertriglyceridemia (TG 1600 mg/dL) without pancreatitis. She is on estrogen therapy and drinks alcohol on weekends.

A 58-year-old man with chronic diarrhea has TSH 0.02, free T4 mildly elevated; uptake scan shows patchy areas of increased uptake in both lobes.

A 35-year-old woman with fatigue and hypotension has low cortisol and high ACTH; 21-hydroxylase adrenal antibodies positive. She asks about sick-day rules.

A 59-year-old smoker has hyponatremia (Na 120), low serum osmolality, high urine osmolality and Na, and a lung hilar mass.

A 46-year-old man with chronic pancreatitis has refractory pain and weight loss; CT shows an inflammatory head mass narrowing the common bile duct.

A 62-year-old woman has hyponatremia and hypothyroidism (TSH 56, free T4 low); clinically euvolemic. After levothyroxine replacement, sodium normalizes.

A 26-year-old man with severe hyperthyroidism is scheduled for thyroidectomy after failed medical therapy.

A 71-year-old woman with T2DM has rapid-onset retinopathy with neovascularization and macular edema.

A 59-year-old man with obesity has OSA and prediabetes; he asks about pharmacologic weight loss without injections.

A 43-year-old woman has episodic flushing, diarrhea, and wheezing; she undergoes hepatic artery embolization for metastatic small-bowel NET. During anesthesia, she develops severe hypotension and bronchospasm.

A 67-year-old man with chronic kidney disease has persistently elevated PTH despite adequate vitamin D and phosphate control; bone pain continues.

A 36-year-old woman has recurrent miscarriages and normal thyroid function tests but positive TPO antibodies. She asks about therapy while trying to conceive.

A 58-year-old man with resistant hypertension and hypokalemia has normal aldosterone and renin, but urinary cortisol is markedly elevated; 11-deoxycortisol elevated.

A 40-year-old man with Paget disease treated years ago returns with new bone pain in the femur; ALP rising. X-ray shows an osteolytic lesion with cortical destruction.

A 55-year-old woman has fatigue and hyponatremia after transsphenoidal resection for Cushing disease. Morning cortisol is low with low ACTH.

A 37-year-old man on long-term TPN develops bone pain and fractures; labs show low phosphate and low 25(OH)D, normal Ca; ALP high.

A 49-year-old woman has episodic headaches and hypertension; she recently started venlafaxine. Plasma metanephrines are mildly elevated. Repeat testing after stopping venlafaxine and avoiding caffeine is normal.

A 70-year-old man with T2DM and PAD has A1c 7.4% on metformin and SGLT2. He asks if tighter control (A1c <6.5%) will improve outcomes.

A 61-year-old woman with known medullary thyroid carcinoma (RET mutation) has rising calcitonin and CEA after thyroidectomy; imaging shows small hepatic and nodal metastases.

A 58-year-old man with long-standing poorly controlled diabetes presents with necrobiosis lipoidica on shins and peripheral neuropathy; A1c 10.4%.