Endocrinology & Diabetes — MCQs

Endocrinology & Diabetes UK Medical PG Practice Questions and MCQs

Question 21: A 30-year-old man presents with recurrent kidney stones. His serum calcium is elevated at 2.8 mmol/L (normal 2.2-2.6). PTH is also elevated. What is the most likely diagnosis?

A. Sarcoidosis
B. Primary hyperparathyroidism (Correct Answer)
C. Malignancy
D. Vitamin D toxicity
E. Milk-alkali syndrome

Explanation: ***Primary hyperparathyroidism***- This condition is unambiguously diagnosed by the presence of **hypercalcemia** (serum calcium 2.8 mmol/L) concurrent with an inappropriately **elevated Parathyroid Hormone (PTH)** level.- The classic clinical feature of hyperparathyroidism is **nephrolithiasis** (recurrent kidney stones), fitting the patient's presentation.*Sarcoidosis*- Hypercalcemia in sarcoidosis is mediated by large amounts of calcitriol (1,25(OH)₂D) produced by activated macrophages, increasing intestinal calcium absorption.- This high calcium level would cause severe **suppression of PTH** via negative feedback, which contradicts the elevated PTH seen in this patient.*Malignancy*- Malignancy-related hypercalcemia (often **Humoral Hypercalcemia of Malignancy**) is usually due to the secretion of **Parathyroid Hormone-related Protein (PTHrP)**.- While PTHrP mimics PTH action, the high resultant calcium would lead to a **suppressed native PTH** level.*Vitamin D toxicity*- Excessive intake of Vitamin D leads to hypercalcemia by promoting calcium absorption and bone resorption.- Diagnosis involves high levels of **25-hydroxyvitamin D** and a profoundly **suppressed PTH** level due to negative feedback.*Milk-alkali syndrome*- This is caused by excessive ingestion of calcium and absorbable alkali, leading to hypercalcemia, metabolic alkalosis, and renal failure.- Like other non-PTH disorders, the resulting hypercalcemia drives PTH levels to become **suppressed**.

Question 22: A 22-year-old woman presents with palpitations, tremor, and anxiety. She mentions her periods have become irregular. On examination, her pulse is 120 bpm and she has a smooth goiter. Free T4 is elevated, TSH is suppressed. What is the next most appropriate investigation?

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

Explanation: ***TSH receptor antibodies*** - Given the patient's age (22), symptoms of hyperthyroidism (palpitations, tremor, anxiety, irregular periods, pulse 120 bpm), suppressed TSH, elevated Free T4, and a **smooth goiter**, the leading diagnosis is **Graves' disease**. - Measuring **TSH receptor antibodies (TRAb)** is the most specific, non-invasive test to confirm Graves' disease, as these stimulating autoantibodies are the direct cause of the hyperfunction. *Thyroid ultrasound* - Ultrasound is useful for evaluating the **morphology** of the thyroid gland (e.g., size, nodularity) and assessing the gland's blood flow (increased vascularity in Graves'). - It is typically utilized after biochemical confirmation and specific antibody testing if nodularity is suspected or to monitor response to treatment, but it does not confirm the underlying **etiology**. *Radioiodine uptake scan* - This scan distinguishes between disorders of increased thyroid hormone **synthesis** (Graves' or toxic nodules, resulting in high uptake) and hormone **release** (thyroiditis, resulting in low uptake). - While accurate, it is generally reserved for cases where antibody testing is inconclusive or contraindicated, or when differentiating between **Graves' disease** and **toxic multinodular goiter**. *Anti-TPO antibodies* - **Anti-TPO antibodies** are markers of general thyroid autoimmunity and cellular destruction, strongly associated with **Hashimoto's thyroiditis** (causing hypothyroidism). - While they may be present in Graves' disease, they are neither specific for nor diagnostic of the **stimulatory** hyperthyroid state and thus are not the priority investigation. *Fine needle aspiration* - **Fine needle aspiration (FNA)** is an invasive procedure indicated almost exclusively for the evaluation of suspicious or dominant **thyroid nodules** to rule out malignancy. - Since the patient has a **smooth goiter** (diffuse enlargement) and confirmed hyperthyroidism, FNA is not indicated at this stage.

Question 23: A 25-year-old woman presents with amenorrhea for 6 months, galactorrhea, and headaches. Visual field testing shows bitemporal hemianopia. What is the most likely diagnosis?

A. Polycystic ovary syndrome
B. Prolactinoma (Correct Answer)
C. Craniopharyngioma
D. Hypothyroidism
E. Pregnancy

Explanation: ***Prolactinoma***- The triad of **amenorrhea**, **galactorrhea**, and signs of a mass lesion (headache, **bitemporal hemianopia**) is the classic presentation of a **prolactin-secreting pituitary macroadenoma** (prolactinoma).- The mass compresses the **optic chiasm**, causing the characteristic **bitemporal hemianopia**, while excessive prolactin inhibits GnRH release, leading to amenorrhea and stimulating breast milk production (galactorrhea).*Polycystic ovary syndrome*- PCOS causes **amenorrhea** (or oligomenorrhea) due to anovulation and is associated with **hyperandrogenism** (hirsutism), not usually galactorrhea.- This condition is an ovarian and metabolic disorder that does not involve structural mass effects on the pituitary or **optic chiasm** that cause visual field defects.*Craniopharyngioma*- While this suprasellar tumor commonly causes chiasmal compression leading to **bitemporal hemianopia**, it primarily causes symptoms of **hypopituitarism** (hormone deficiencies) and growth issues.- It is typically not the cause of isolated **hyperprolactinemia** and galactorrhea, unless it severely disrupts the pituitary stalk.*Hypothyroidism*- Severe primary hypothyroidism can elevate prolactin levels through increased **TRH** stimulation, potentially causing secondary amenorrhea and galactorrhea.- However, hypothyroidism is a generalized endocrine disorder and does not cause a localized **mass effect** resulting in visual field loss like bitemporal hemianopia.*Pregnancy*- Pregnancy causes amenorrhea and galactorrhea (due to high estrogen/progesterone and prolactin levels, respectively), but it should be ruled out first. - It is a physiological state and is not associated with the pathological **suprasellar mass lesion** causing **bitemporal hemianopia** described in this patient.

Question 24: A 45-year-old woman presents with fatigue, hair loss, and cold intolerance. Blood tests show TSH 15 mU/L (normal 0.4-4.0), free T4 8 pmol/L (normal 10-22). Anti-TPO antibodies are positive. What is the most likely diagnosis?

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

Explanation: ***Hashimoto's thyroiditis***- The combination of severe **primary hypothyroidism** (high TSH, low free T4) and the presence of **Anti-TPO antibodies** is pathognomonic for Hashimoto's thyroiditis, the most common cause of hypothyroidism.- Clinical symptoms like **fatigue**, cold intolerance, and **hair loss** are classic manifestations of decreased circulating thyroid hormone levels.*De Quervain's thyroiditis*- This condition is a **subacute granulomatous thyroiditis** typically presenting with painful thyroid tenderness and often follows a viral illness.- While it can cause transient hypothyroidism, the initial phase is usually **hyperthyroidism**, and it is not characterized by persistently high autoantibody titers.*Pituitary adenoma*- A pituitary adenoma causing hypocortisolism would lead to **central hypothyroidism** (secondary hypothyroidism), characterized by a low or inappropriately normal TSH level despite low free T4.- This diagnosis is inconsistent with the presented lab results, which show high TSH (indicating a primary failure at the **thyroid gland** level).*Iodine deficiency*- Although severe **iodine deficiency** causes primary hypothyroidism and TSH elevation, it would typically present without the high titers of **Anti-TPO antibodies**.- This etiology is rare in regions with adequate salt iodination and usually leads to a large, **endemic goiter**.*Drug-induced hypothyroidism*- This diagnosis is excluded as there is no mention of relevant drug exposure (e.g., **amiodarone** or **lithium**) in the patient's history.- While drug-induced hypothyroidism can cause TSH elevation, the presence of strong **autoantibody positivity** points toward an underlying autoimmune disease.

Question 25: A 25-year-old woman presents with palpitations and anxiety. She has lost 5kg in weight despite increased appetite. On examination, her pulse is 110 bpm and irregular. What investigation would be most helpful?

A. 24-hour Holter monitor
B. Echocardiogram
C. Thyroid function tests (Correct Answer)
D. Full blood count
E. Urea and electrolytes

Explanation: ***Thyroid function tests***- These symptoms—palpitations, anxiety, significant weight loss despite increased appetite, and an irregular pulse—are highly classic presentations of **hyperthyroidism** (thyrotoxicosis).- The irregular pulse (tachycardia) is likely due to **atrial fibrillation** secondary to thyrotoxicosis, making thyroid function tests (TSH, free T3/T4) the essential step to establish the primary diagnosis.*24-hour Holter monitor*- While the irregular pulse requires further evaluation, the Holter monitor only confirms the cardiac rhythm (e.g., **atrial fibrillation**) but does not identify the underlying systemic cause of the patient's hyperdynamic state.- In this clinical scenario, treatment of the underlying **thyrotoxicosis** is mandatory and directly guided by the thyroid hormone levels.*Echocardiogram*- An echocardiogram assesses cardiac structure and function, which may show changes like **thyrotoxic cardiomyopathy** or valvular disease.- However, the systemic hypermetabolic symptoms point strongly to an endocrine disorder, which must be investigated first before detailed structural assessment.*Full blood count*- A full blood count (FBC) primarily screens for **anemia** or indications of infection/hematologic malignancy. - It is not the primary diagnostic test for hypermetabolic symptoms like weight loss, anxiety, and palpitations indicative of thyroid imbalance.*Urea and electrolytes*- This screens for renal function and electrolyte imbalances (e.g., hypokalemia), which can affect heart rhythm but do not explain the patient's defining **hypermetabolic state** and weight loss.- While important for completeness, it is not the most helpful initial test for diagnosing the cause of this clinical presentation.

Question 26: A 55-year-old man with diabetes presents with a painless ulcer on his right great toe. On examination, he has absent foot pulses and reduced sensation to monofilament testing. What is the most important initial investigation?

A. Ankle-brachial pressure index (Correct Answer)
B. HbA1c
C. X-ray of foot
D. Wound culture
E. Doppler ultrasound

Explanation: ***Ankle-brachial pressure index*** - The presence of a **painless ulcer**, **absent foot pulses**, and **reduced sensation** in a diabetic patient strongly suggests **peripheral artery disease (PAD)** and **diabetic neuropathy**. The **Ankle-brachial pressure index (ABPI)** is the most important initial investigation to assess for PAD. - ABPI measures the ratio of blood pressure in the ankle to that in the arm, providing a crucial non-invasive assessment of **vascular compromise** to determine if arterial insufficiency is contributing to the ulcer. *HbA1c* - While **HbA1c** is important for assessing long-term **glycemic control** in diabetes, it is not the most immediate or crucial investigation for managing an existing foot ulcer that presents with signs of vascular insufficiency and neuropathy. - Poor glycemic control contributes to microvascular and macrovascular complications, but addressing the immediate cause of the ulcer (vascular status) takes precedence for initial investigation. *X-ray of foot* - An **X-ray of the foot** is useful for identifying **osteomyelitis** or **Charcot neuroarthropathy**, which are common complications of diabetic foot ulcers. - However, the primary concern with absent pulses and a painless ulcer is vascular supply, and an X-ray would not directly assess the arterial blood flow. *Wound culture* - A **wound culture** is essential for identifying bacterial infection and guiding antibiotic therapy, especially in a diabetic foot ulcer. - Yet, assessing the underlying vascular status with ABPI is more critical as the initial step because adequate blood supply is fundamental for wound healing, regardless of infection. *Doppler ultrasound* - A **Doppler ultrasound** is an excellent follow-up investigation to visualize blood flow, assess arterial stenosis, and map the vascular anatomy if the ABPI is abnormal. - However, the **ABPI** is generally considered the most important **initial screening tool** for PAD due to its simplicity and ability to quantitatively assess overall limb perfusion before proceeding to more detailed imaging.

Question 27: A 22-year-old woman presents with a 2-week history of palpitations, weight loss, heat intolerance, and tremor. On examination, she has a smooth goiter and eye signs including lid lag. 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. Toxic adenoma
E. Factitious hyperthyroidism

Explanation: ***Graves' disease***- The combination of classic hyperthyroid symptoms (palpitations, weight loss, heat intolerance, tremor), a **smooth goiter**, and characteristic **eye signs (lid lag)** strongly indicates Graves' disease. - The lab results of **suppressed TSH** and **elevated free T4** confirm hyperthyroidism, consistent with this autoimmune condition mediated by TSH receptor antibodies.*Toxic multinodular goiter*- This condition typically affects **older individuals** and presents with an **irregular, nodular** thyroid gland on palpation, not a smooth goiter. - It is not associated with **Graves' ophthalmopathy** or eye signs like lid lag, which are autoimmune features.*Thyroiditis*- While thyroiditis can cause hyperthyroidism, it is often associated with **neck pain** or tenderness and typically presents with a **transient phase** of hyperthyroidism. - It does not usually cause sustained **ophthalmopathy** or a smooth, diffuse goiter in the manner seen in Graves' disease.*Toxic adenoma*- This is characterized by a **single, autonomously functioning thyroid nodule**, in contrast to the diffuse goiter described. - Toxic adenoma does not involve the autoimmune process that causes **Graves' ophthalmopathy** or other characteristic eye signs.*Factitious hyperthyroidism*- In this condition, the hyperthyroidism is due to exogenous thyroid hormone intake, which would result in a **small or non-palpable thyroid gland** due to TSH suppression, not a goiter. - The presence of **eye signs** (ophthalmopathy) is also inconsistent, as this lacks the autoimmune basis of Graves' disease.

Question 28: A 65-year-old man with type 2 diabetes presents for routine review. His HbA1c is 75 mmol/mol (9.0%) despite maximum tolerated metformin. His eGFR is 45 ml/min/1.73m². What is the most appropriate next step?

A. Add gliclazide
B. Add sitagliptin
C. Add empagliflozin (Correct Answer)
D. Start insulin
E. Add pioglitazone

Explanation: ***Add empagliflozin***1. This patient has poor glycemic control (HbA1c 9.0%) and underlying moderate **Chronic Kidney Disease (CKD)** (eGFR 45 ml/min/1.73m²), making an **SGLT2 inhibitor** the preferred second-line agent after metformin failure.2. **Empagliflozin** is recommended in major guidelines (ADA/EASD/NICE) for T2DM patients with CKD because it provides established **cardiovascular** and **renal protection** independent of glycemic effects, and is safe and beneficial at this eGFR level.*Add gliclazide*1. Sulfonylureas like gliclazide significantly increase the risk of **hypoglycemia**, which is exacerbated in the setting of **CKD** due to reduced renal clearance.2. Modern diabetes management guidelines prioritize agents like **SGLT2 inhibitors** as second-line therapy when CKD is present, given their lower risk profile and specific organ protection benefits.*Add sitagliptin*1. DPP-4 inhibitors are generally safe and have a low hypoglycemia risk, but they require a **dose reduction** in patients with an eGFR below 50 ml/min/1.73m².2. Although a tenable option, **sitagliptin** does not offer the robust, guideline-mandated level of **cardiorenal protection** seen with empagliflozin in patients with established CKD.*Start insulin*1. Insulin is associated with increased risks of **hypoglycemia** and **weight gain**, and is typically considered after failure of optimal dual or triple oral therapy.2. It is usually reserved for patients with more severe decompensation (HbA1c >10%) or presence of catabolism, which is not described here, making it an overly aggressive initial second-step choice. *Add pioglitazone*1. Pioglitazone (a TZD) is associated with an increased risk of **fluid retention**, leading to cautious use or contraindication in patients at risk of or with **congestive heart failure**.2. It also causes **weight gain** and does not provide the robust **renal protective benefits** that SGLT2 inhibitors offer in patients with CKD.

Question 29: A 35-year-old man presents with recurrent peptic ulcers and diarrhea. Serum gastrin is markedly elevated. CT shows a pancreatic mass. What is the most likely diagnosis?

A. Insulinoma
B. Gastrinoma (Correct Answer)
C. Glucagonoma
D. VIPoma
E. Pancreatic adenocarcinoma

Explanation: ***Gastrinoma***- The presence of **recurrent peptic ulcers**, diarrhea, and markedly **elevated serum gastrin levels** is the classic triad defining **Zollinger-Ellison syndrome (ZES)**, which is caused by a gastrin-secreting tumor (**gastrinoma**).- The visualization of a **pancreatic mass** confirms the location of this neuroendocrine tumor, which drives excessive gastric acid secretion leading to refractory ulcer disease.*Insulinoma*- This tumor secretes **insulin** and typically presents with symptoms related to **hypoglycemia** (e.g., sweating, confusion, palpitations), particularly **fasting hypoglycemia**.- Diagnosis is based on the **Whipple triad** and elevated insulin/C-peptide levels, not gastrointestinal symptoms like refractory ulcers, or elevated gastrin.*Glucagonoma*- This tumor secretes **glucagon** and is classically associated with the diagnostic rash **necrolytic migratory erythema**, as well as **diabetes mellitus** and **weight loss**.- It does not cause acid hypersecretion or peptic ulcers; the clinical picture is dictated by glucagon excess.*VIPoma*- This tumor secretes **Vasoactive Intestinal Peptide (VIP)** and causes **Verner-Morrison syndrome** (pancreatic cholera).- The hallmark presentation is profuse, lifelong watery **diarrhea** associated with **hypokalemia** and **achlorhydria** (WDHA syndrome), lacking the high gastrin and peptic ulceration seen here.*Pancreatic adenocarcinoma*- This is an exocrine tumor that typically presents with non-specific constitutional symptoms like **weight loss** and **new-onset diabetes**, or features of bile duct obstruction like painless **jaundice**.- It does not cause a hormonal syndrome resulting in elevated gastrin and peptic ulcers, as it is not a neuroendocrine tumor.

Question 30: A 42-year-old woman presents with fatigue, cold intolerance, and weight gain. She has a goiter and her TSH is 25 mU/L with low free T4. Anti-TPO antibodies are strongly positive. What is the most likely diagnosis?

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

Explanation: ***Hashimoto's thyroiditis***- The constellation of symptoms (fatigue, cold intolerance, weight gain), **primary hypothyroidism** (High **TSH**, Low **Free T4**), goiter, and strongly positive **Anti-TPO antibodies** is pathognomonic for **Hashimoto's thyroiditis**.- This is the most common cause of primary hypothyroidism in **iodine-sufficient** regions, resulting from chronic autoimmune destruction of the thyroid gland.*De Quervain's thyroiditis*- This condition typically presents with a **tender** or **painful** thyroid gland, often following a viral upper respiratory infection, which is not described in this patient.- **De Quervain's** often starts with a transient **hyperthyroid** phase due to follicular destruction, differentiating it from the chronic hypothyroid state presented here.*Postpartum thyroiditis*- This condition occurs exclusively within **1 year after childbirth**; given the patient's age and lack of recent obstetric history, this is less likely.- While it can be destructive and cause hypothyroidism, it is often a **transient** process, unlike the chronic, established hypothyroidism suggested by the severely elevated TSH.*Iodine deficiency*- While severe iodine deficiency causes goiter and hypothyroidism (High TSH, Low T4), it is not an autoimmune process.- A diagnosis of iodine deficiency would not be associated with the high titers of **Anti-TPO antibodies** observed in this patient.*Drug-induced hypothyroidism*- Hypothyroidism induced by drugs (e.g., **amiodarone**, **lithium**) satisfies the TSH/T4 criteria but lacks the definitive autoimmune signature of strongly positive **Anti-TPO antibodies**.- This diagnosis requires a history of exposure to causative medication, which is not provided, and the specific autoantibody profile strongly favors **Hashimoto's**.

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