Endocrinology & Diabetes — MCQs

Endocrinology & Diabetes UK Medical PG Practice Questions and MCQs

Question 11: A 36-year-old woman presents with recurrent episodes of severe abdominal pain and confusion. Her urine turns dark during attacks. What is the most likely diagnosis?

A. Acute intermittent porphyria (Correct Answer)
B. Inflammatory bowel disease
C. Familial Mediterranean fever
D. Hereditary angioedema
E. Systemic lupus erythematosus

Explanation: ***Acute intermittent porphyria***- Recurrent episodes of severe **abdominal pain** (often lacking physical findings) combined with acute *neuropsychiatric symptoms* like confusion is characteristic of this condition.- The urine turning **dark** (often described as port-wine colored) during the attack is caused by high levels of porphobilinogen and porphyrins, confirming the diagnosis.*Inflammatory bowel disease*- Primary symptoms are **chronic diarrhea**, **rectal bleeding**, and **weight loss**, indicating chronic inflammation of the GI tract.- While abdominal pain is common, IBD attacks do not cause significant **acute confusion** or the pathognomonic **dark urine** indicative of porphyria.*Familial Mediterranean fever*- Characterized by recurrent, self-limiting episodes of **fever** and **serositis** (**peritonitis**, pleuritis, arthritis), typically lasting 1–3 days.- Though it is a cause of recurrent severe abdominal pain, FMF is not associated with the primary neurological derangements (confusion) or the **dark urine** witnessed in this case.*Hereditary angioedema*- Acute abdominal pain is caused by transient **edema of the bowel wall**, often accompanied by subcutaneous or mucosal swelling of other areas, occasionally involving the larynx.- HAE is a complement deficiency (low C1 inhibitor) and does not produce **confusion** as a primary symptom or cause the chemical changes that result in **dark urine**.*Systemic lupus erythematosus*- Associated with diverse systemic features like **arthritis**, **malar rash**, and **glomerulonephritis**, often diagnosed via autoantibodies (ANA, Anti-dsDNA).- Although neuropsychiatric SLE can cause confusion, it does not typically present with the combination of severe, unexplained abdominal pain and **dark, porphyrin-rich urine**.

Question 12: A 35-year-old woman presents with recurrent hypoglycemic episodes, particularly when fasting. C-peptide and insulin levels are elevated during hypoglycemia. What is the most likely diagnosis?

A. Factitious hypoglycemia
B. Insulinoma (Correct Answer)
C. Adrenal insufficiency
D. Liver disease
E. Alcohol-induced hypoglycemia

Explanation: ***Insulinoma*** - The classic biochemical signature of an **insulinoma** is hypoglycemia with concurrently **elevated insulin and C-peptide levels**, indicating excessive *endogenous* insulin production. - This neuroendocrine tumor autonomously hypersecretes insulin, leading to recurrent **fasting hypoglycemia**. *Factitious hypoglycemia* - If hypoglycemia is due to **exogenous insulin** injection, insulin levels would be high, but C-peptide levels would be **suppressed** due to negative feedback. - If caused by **sulfonylurea use**, C-peptide would be elevated, but a **drug screen** would confirm the presence of the secretagogue. *Adrenal insufficiency* - **Adrenal insufficiency** (cortisol deficiency) causes hypoglycemia by impairing essential glucose counter-regulatory mechanisms like **gluconeogenesis**. - In this condition, hypoglycemia is associated with **low or normal insulin and C-peptide levels**, as hyperinsulinemia is not the cause. *Liver disease* - Severe **liver disease** can cause fasting hypoglycemia due to the liver's inability to perform adequate **gluconeogenesis** and glycogenolysis. - Insulin and C-peptide levels would typically be low or **within the normal fasting range**, not elevated, as the body attempts to suppress insulin. *Alcohol-induced hypoglycemia* - **Alcohol-induced hypoglycemia** occurs because alcohol metabolism inhibits key enzymes required for **gluconeogenesis**. - This type of hypoglycemia involves impaired glucose production, and consequently, both **insulin and C-peptide levels are suppressed**.

Question 13: A 47-year-old woman presents with recurrent episodes of flushing, diarrhea, and wheezing. CT shows liver metastases and a small bowel mass. What is the most appropriate biochemical test?

A. Serum gastrin
B. 24-hour urine 5-HIAA (Correct Answer)
C. Serum chromogranin A
D. Serum VIP
E. Serum glucagon

Explanation: ***24-hour urine 5-HIAA*** - This test measures **5-hydroxyindoleacetic acid** (5-HIAA), the primary stable metabolite of **serotonin**, which is often massively overproduced by functioning **carcinoid tumors**. - The classic triad of **flushing**, **diarrhea**, and **wheezing** indicates **carcinoid syndrome**, which typically occurs when liver metastases prevent hepatic degradation of serotonin. *Serum gastrin* - Elevated **serum gastrin** is the diagnostic marker for **Zollinger-Ellison syndrome** (gastrinoma), which presents primarily with severe peptic ulcer disease and gastroesophageal reflux disease (GERD). - While gastrinomas are neuroendocrine tumors (NETs), they do not cause the characteristic triad of **flushing** and **wheezing** seen in this patient. *Serum chromogranin A* - **Chromogranin A (CgA)** is a general, non-specific marker for neuroendocrine tumors (NETs) and is often used for tumor screening and monitoring treatment response. - Although CgA is often elevated in carcinoid syndrome, the **24-hour urine 5-HIAA test** is the more specific and definitive biochemical test for diagnosing a *functioning* carcinoid tumor. *Serum VIP* - **Vasoactive intestinal peptide (VIP)** is the marker for **VIPoma**, which typically presents with the "WDHA" syndrome: **Watery Diarrhea**, **Hypokalemia**, and **Achlorhydria**. - The primary symptoms of **flushing** and **wheezing** are highly suggestive of serotonin/histamine release (**carcinoid syndrome**), not VIP hypersecretion. *Serum glucagon* - Elevated **serum glucagon** is diagnostic for **Glucagonoma**, a separate NET characterized by **necrolytic migratory erythema**, glucose intolerance (**diabetes mellitus**), and weight loss. - Glucagonoma symptoms do not include the syndrome of **flushing, diarrhea, and wheezing** observed in this patient.

Question 14: A 56-year-old diabetic man presents with a painless foot ulcer with exposed bone. X-ray shows osteolytic changes. What is the most likely complication?

A. Cellulitis
B. Osteomyelitis (Correct Answer)
C. Charcot arthropathy
D. Peripheral arterial disease
E. Neuropathic ulcer

Explanation: ***Osteomyelitis*** - The combination of a deep, chronic ulcer with **exposed bone** and the *painless* nature (due to **diabetic neuropathy**) strongly points to an underlying bone infection. - **Osteolytic changes** on X-ray are characteristic of bone destruction caused by the infectious process, confirming osteomyelitis. *Cellulitis* - This is a **superficial soft tissue infection** with warmth, erythema, and pain, but it does not involve bone. - It does not account for the **exposed bone** or the **osteolytic changes** seen on the X-ray. *Charcot arthropathy* - This is a non-infectious condition leading to **progressive joint destruction** and bony deformities, often in a 'rocker-bottom' foot. - While it involves bone changes, it typically lacks an open ulcer with **exposed bone** indicative of active infection. *Peripheral arterial disease* - This causes **ischemic ulcers** due to poor blood flow, often painful, and is a **risk factor** for infection, but not the infection itself. - It does not directly explain the **exposed bone** or the **osteolytic changes**, which point to established infection. *Neuropathic ulcer* - This is the **initial painless lesion** due to neuropathy and trauma, typically over pressure points. - The presence of **exposed bone** and **bony destruction** on X-ray indicates that the neuropathic ulcer has progressed to osteomyelitis, which is the specific complication here.

Question 15: A 26-year-old woman presents with amenorrhea, galactorrhea, and visual field defects. Prolactin level is 15,000 mU/L. MRI shows a 3cm pituitary mass. What is the most appropriate initial treatment?

A. Transsphenoidal surgery
B. Cabergoline (Correct Answer)
C. Bromocriptine
D. Radiotherapy
E. Octreotide

Explanation: ***Cabergoline***- **Dopamine agonists** are the standard first-line treatment for virtually all prolactinomas, including **macroprolactinomas** causing mass effect like visual field defects.- Cabergoline is preferred over bromocriptine due to its better efficacy, less frequent dosing (twice weekly), and improved tolerability, leading to rapid tumor shrinkage and normalization of **prolactin** levels.*Transsphenoidal surgery*- Surgery is indicated primarily for prolactinomas that are resistant to **dopamine agonists** or those presenting with acute complications like pituitary **apoplexy** or rapid visual loss despite medical therapy.- It is generally less effective than dopamine agonists for prolactin reduction and carries higher risks of complications, including **hypopituitarism**.*Bromocriptine*- Bromocriptine is an effective **dopamine agonist** for prolactinomas but is typically reserved as a second choice if cabergoline is unavailable or poorly tolerated.- It requires daily or twice-daily dosing and has a higher incidence of gastrointestinal and central nervous system side effects compared to **cabergoline**.*Radiotherapy*- Radiotherapy is typically a tertiary treatment option reserved for cases of refractory or **malignant prolactinomas** that have failed both optimal medical therapy (dopamine agonists) and surgical resection.- Its effects are slow (taking months to years), and it carries significant risks, including inducing **hypopituitarism** and increasing the risk of secondary tumors.*Octreotide*- Octreotide is a **somatostatin analog** used primarily for tumors that express somatostatin receptors, such as **GH-producing adenomas** (Acromegaly) or TSH-producing tumors.- It is generally ineffective as a primary treatment for prolactinomas, which respond best to **dopamine agonists**.

Question 16: A 22-year-old woman presents with palpitations, tremor, and anxiety. She has lost 8kg in weight despite increased appetite. On examination, she has a smooth goiter and her eyes appear prominent. TSH is <0.01 mU/L, free T4 is elevated. What is the most likely diagnosis?

A. Toxic multinodular goiter
B. Graves' disease (Correct Answer)
C. Thyroiditis
D. Thyroid cancer
E. Factitious hyperthyroidism

Explanation: ***Graves' disease***- The constellation of severe hyperthyroid symptoms (**palpitations, tremor, anxiety, weight loss** despite increased appetite), suppressed TSH, elevated free T4, and specific autoimmune features like a **smooth, diffuse goiter** and **prominent eyes (exophthalmos)** is pathognomonic.- This condition is caused by stimulating **TSH receptor antibodies (TRAb)**, leading to uncontrolled thyroid hormone synthesis and release.*Toxic multinodular goiter*- This diagnosis typically presents in **older patients** (over 50) and involves a **heterogeneous, nodular goiter** rather than the smooth, diffuse enlargement seen here.- Although it causes hyperthyroidism, it is not associated with the presence of the specific autoimmune finding of **Graves' ophthalmopathy** (prominent eyes).*Thyroiditis*- Hyperthyroidism in thyroiditis is usually **transient** (due to leakage of preformed hormone) and often presents with a painful gland (subacute thyroiditis) or is followed by hypothyroidism.- It is not an etiologic cause of sustained hyperthyroidism and lacks the key specific finding of **prominent eyes** seen in this patient.*Thyroid cancer*- Most thyroid cancers are **euthyroid** or associated only with mild thyroid dysfunction, typically presenting as a discreet, solitary nodule rather than a smooth, diffuse gland.- It is extremely rare for thyroid carcinoma to present with such florid hyperthyroid symptoms and associated **Graves' ophthalmopathy**.*Factitious hyperthyroidism*- This results from surreptitious ingestion of exogenous thyroid hormone; labs would match (**suppressed TSH, high free T4**), but the autoimmune manifestations would be absent.- Patients with this disorder usually **do not have a goiter** or specific eye findings like **Graves' ophthalmopathy**.

Question 17: A 40-year-old woman presents with fatigue, weight gain, and cold intolerance. She has a family history of autoimmune disease. Blood tests show TSH 25 mU/L, free T4 6 pmol/L, positive anti-TPO antibodies. What is the most likely diagnosis?

A. Hashimoto's thyroiditis (Correct Answer)
B. De Quervain's thyroiditis
C. Postpartum thyroiditis
D. Drug-induced hypothyroidism
E. Iodine deficiency

Explanation: ***Hashimoto's thyroiditis*** - The combination of classic symptoms of **hypothyroidism** (fatigue, weight gain, cold intolerance), laboratory findings of **primary hypothyroidism** (high **TSH**, low **free T4**), and strongly positive **anti-TPO antibodies** is diagnostic. - This is the most common cause of primary hypothyroidism, driven by autoimmune destruction of the thyroid gland, often with a **family history of autoimmune disease**. *De Quervain's thyroiditis* - Typically presents with a **painful** and **tender thyroid gland**, often following an upper respiratory infection. - It usually involves a transient hyperthyroid phase followed by a hypothyroid phase, and **anti-TPO antibodies are typically negative** or mildly elevated. *Postpartum thyroiditis* - Occurs specifically in women **within 12 months after childbirth**, a history not indicated in this case. - While it is an autoimmune process, it often presents with a biphasic course (hyperthyroidism followed by hypothyroidism) and is generally **transient**, unlike the sustained severe hypothyroidism suggested here. *Drug-induced hypothyroidism* - This diagnosis requires a clear history of exposure to specific medications known to cause hypothyroidism, such as **lithium** or **amiodarone**. - Although it can cause low free T4 and high TSH, it is **not typically associated with positive anti-TPO antibodies**, which indicate an underlying autoimmune process. *Iodine deficiency* - Causes hypothyroidism due to insufficient **iodine** to synthesize thyroid hormones, which is rare in developed countries with iodized salt. - While it leads to high TSH and low T4, it is **not associated with positive anti-TPO antibodies**, as it is a nutritional deficiency, not an autoimmune condition.

Question 18: A 60-year-old man with diabetes presents with a painless red eye and gradually worsening vision over several days. Ophthalmoscopy shows new vessel formation on the retina and vitreous hemorrhage. What is the most likely diagnosis?

A. Diabetic retinopathy (Correct Answer)
B. Hypertensive retinopathy
C. Age-related macular degeneration
D. Retinal detachment
E. Acute angle-closure glaucoma

Explanation: ***Diabetic retinopathy*** - The presence of **new vessel formation** (**neovascularization**) and **vitreous hemorrhage** in a patient with **diabetes mellitus** is the hallmark presentation of **proliferative diabetic retinopathy (PDR)**. - PDR causes vision loss when these fragile new vessels bleed into the vitreous (**vitreous hemorrhage**) or cause scarring leading to **tractional retinal detachment**. *Hypertensive retinopathy* - This condition typically manifests with classic signs like **cotton-wool spots**, flame-shaped hemorrhages, and **arteriolar narrowing** due to severe hypertension, not widespread neovascularization. - While hypertension often coexists with diabetes, the primary pathology described (neovascularization leading to bleeding) is specific to the microvascular damage caused by **uncontrolled hyperglycemia**. *Age-related macular degeneration* - This disease primarily affects the **macula** and central vision, causing distortion (**metamorphopsia**) and blurring, usually progressing slowly over time. - While the 'wet' form involves **choroidal neovascularization**, this neovascularization is localized subretinally, generally causing subretinal hemorrhage rather than large **vitreous hemorrhage**. *Retinal detachment* - Symptoms of retinal detachment usually include sudden onset of numerous **floaters**, light flashes (**photopsia**), and a **curtain or shadow** obscuring vision. - While proliferative diabetic retinopathy is a common cause of **tractional retinal detachment**, the primary findings here (neovascularization and hemorrhage) point to the underlying **proliferative disease** rather than just the resultant mechanical detachment. *Acute angle-closure glaucoma* - This is characterized by an **acute, painful** red eye, severe visual loss, ciliary flush, and a fixed mid-dilated pupil, differentiating it from the painless, gradual onset seen here. - The mechanism involves a sudden spike in intraocular pressure due to compromised outflow, and it does not typically feature the **retinal neovascularization** and **vitreous hemorrhage** described.

Question 19: A 30-year-old woman presents with palpitations, heat intolerance, and weight loss. She has bilateral exophthalmos and pretibial myxedema. TSH is suppressed, free T4 is elevated. What is the most specific test to confirm the diagnosis?

A. Thyroid ultrasound
B. Radioiodine uptake scan
C. TSH receptor antibodies (Correct Answer)
D. Anti-TPO antibodies
E. Thyroglobulin levels

Explanation: ***TSH receptor antibodies*** - The clinical presentation, including **palpitations**, **heat intolerance**, **weight loss**, **bilateral exophthalmos**, and **pretibial myxedema**, along with suppressed TSH and elevated free T4, are pathognomonic for **Graves' disease**. - **TSH receptor antibodies** (**TRAb** or **TSI**) are highly specific for Graves' disease, as they are the autoimmune antibodies that stimulate the TSH receptor, leading to excessive thyroid hormone production. *Thyroid ultrasound* - A thyroid ultrasound provides anatomical information about the thyroid gland, such as size, presence of nodules, and blood flow (**diffuse hypervascularity** in Graves'). - However, it does not specifically confirm the autoimmune etiology of **Graves' disease** and is not the most specific diagnostic test for the underlying cause. *Radioiodine uptake scan* - A **radioiodine uptake scan** (RAIU) measures the thyroid gland's activity and helps differentiate causes of hyperthyroidism (e.g., high uptake in Graves' vs. low uptake in thyroiditis). - While useful for diagnosis, it is less specific than TRAb for confirming Graves' disease, as other conditions like **toxic multinodular goiter** can also show high uptake. *Anti-TPO antibodies* - **Anti-thyroid peroxidase** (**Anti-TPO**) antibodies are commonly found in both **Graves' disease** and **Hashimoto's thyroiditis**. - Although often present in Graves' disease, they are not specific enough to differentiate it from other autoimmune thyroid conditions. *Thyroglobulin levels* - **Thyroglobulin** is a protein produced by thyroid follicular cells, and its levels are often elevated in various forms of hyperthyroidism, including Graves' disease and thyroiditis. - This test is primarily used as a tumor marker for monitoring patients with differentiated **thyroid cancer** after thyroidectomy, not as a specific diagnostic test for Graves' disease.

Question 20: A 45-year-old woman presents with fatigue, weight gain, and depression. She also complains of dry skin and constipation. Blood tests show TSH 12 mU/L, free T4 8 pmol/L. What is the most appropriate treatment?

A. Liothyronine (T3)
B. Levothyroxine (T4) (Correct Answer)
C. Combined T3/T4 therapy
D. Iodine supplementation
E. No treatment needed

Explanation: ***Levothyroxine (T4)***- This is the standard, first-line treatment for primary **hypothyroidism** due to its long half-life, allowing for once-daily dosing and ensuring stable **thyroid hormone** levels.- It acts as a prohormone, being converted peripherally to **active T3** (triiodothyronine) to meet the body's metabolic needs, effectively replacing the deficit confirmed by the high TSH and low free T4.*Liothyronine (T3)*- Liothyronine is **T3**, which has a very short half-life, leading to fluctuating serum concentrations and potentially causing **thyrotoxic symptoms** or cardiac risks if not carefully monitored.- It is generally reserved only for acute conditions like **myxedema coma** or in rare cases where patients do not adequately convert T4 to T3.*Combined T3/T4 therapy*- While some patients are treated with combination therapy, **Levothyroxine monotherapy** remains the gold standard because it effectively normalizes TSH and alleviates symptoms in the majority of patients.- Combination therapy is typically considered only if T4 monotherapy fails to alleviate symptoms, and it requires more complex monitoring due to the risk of **T3 toxicity*.*Iodine supplementation*- Iodine supplementation is only appropriate for **iodine deficiency** etiology of hypothyroidism, which is less common in developed countries and requires specific evaluation.- For the most common cause of hypothyroidism (**Hashimoto's thyroiditis**), the gland is incapable of producing adequate hormone regardless of iodine status, requiring direct hormone replacement.*No treatment needed*- Treatment is mandatory as the patient is symptomatic (fatigue, constipation, depression) and has overt hypothyroidism (TSH >10 mU/L and Low **free T4**).- Untreated overt hypothyroidism leads to progression of symptoms and long-term risks such as **cardiovascular disease** and neurological impairment.

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Diabetic emergencies (DKA, HHS)

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Thyroid disorders

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