Endocrinology Practice Questions

Q: A 14-year-old male presents with type I diabetes mellitus. His mother wants to know if the boy's brother might also have an increased risk of getting the disease. Which of the following genotypes, if present in the brother, would be associated with the greatest risk of developing diabetes?

DR3/DR4. ***DR3/DR4*** - The combination of **HLA-DR3** and **HLA-DR4** is the strongest genetic risk factor for **Type 1 diabetes mellitus (T1DM)**, particularly in individuals of European descent. - These alleles are associated with increased susceptibility to autoimmune destruction of pancreatic beta cells [1]. *DR2/DR4* - While **DR4** is a risk allele for Type 1 diabetes, **DR2 (specifically DRB1*1501)** is generally considered to be protective against the disease. - The presence of the protective DR2 allele would likely mitigate the increased risk conferred by DR4. *DR2/DR2* - **HLA-DR2 (DRB1*1501)** is largely recognized as a protective allele against **Type 1 diabetes**, meaning individuals with this genotype have a lower risk of developing the disease [1]. - Its presence is associated with a reduced susceptibility to autoimmune conditions like T1DM. *B27/B27* - **HLA-B27** is primarily associated with **seronegative spondyloarthropathies** such as ankylosing spondylitis and reactive arthritis, and not directly with an increased risk of Type 1 diabetes mellitus. - This allele is involved in different autoimmune pathways than those implicated in T1DM.

Q: What is the characteristic hormone pattern in hypergonadotropic hypogonadism?

Increase FSH increase LH. ***Increase FSH increase LH*** - **Hypergonadotropic hypogonadism** indicates primary gonadal failure, meaning the gonads (testes or ovaries) are not producing enough sex hormones (testosterone or estrogen). - The pituitary gland, recognizing the low sex hormone levels, compensates by increasing the production of **follicle-stimulating hormone (FSH)** and **luteinizing hormone (LH)** to stimulate the dysfunctional gonads [1]. *Decrease FSH and increase LH* - A decrease in FSH and an increase in LH is not a typical pattern for primary hypogonadism and could suggest a different endocrine disorder or a transient fluctuation. - This pattern is more commonly seen in conditions like **polycystic ovary syndrome (PCOS)** in women, where the LH/FSH ratio is elevated [2]. *Decrease FSH and LH* - A decrease in both FSH and LH indicates **hypogonadotropic hypogonadism**, which is secondary hypogonadism caused by dysfunction at the level of the pituitary gland or hypothalamus [2]. - In this scenario, the pituitary is not producing enough gonadotropins to stimulate the gonads, leading to low sex hormone levels. *Increase FSH decrease LH* - An isolated increase in FSH with a decrease in LH is an unusual pattern for most common forms of hypogonadism. - While FSH can sometimes be preferentially elevated in early stages of gonadal failure, a decrease in LH would be contradictory to the compensatory mechanism of the pituitary in hypergonadotropic hypogonadism.

Q: Hypertension with androgenization of a female child is a feature of congenital adrenal hyperplasia due to deficiency of:

C-11 hydroxylase. ***C-11 hydroxylase*** - Deficiency of **C-11 hydroxylase** leads to accumulation of 11-deoxycorticosterone (DOC) and 11-deoxycortisol [1]. - **DOC** has mineralocorticoid activity, causing **hypertension**, while the shunting of precursors to the adrenal androgen pathway results in **androgenization** [1]. *C-17 hydroxylase* - **C-17 hydroxylase deficiency** results in decreased sex steroids and cortisol, leading to hypertension due to increased mineralocorticoids [1]. - However, the lack of androgens would cause **undervirilization** in males and **lack of secondary sexual characteristics** in females, rather than androgenization. *C-21 hydroxylase* - **C-21 hydroxylase deficiency** is the most common cause of congenital adrenal hyperplasia [1]. - It leads to **androgenization** but typically causes **hypotension** and **salt-wasting** due to deficient mineralocorticoid production, not hypertension. *Desmolase* - **Desmolase (P450scc) deficiency** is a very severe form of congenital adrenal hyperplasia, impairing the synthesis of all adrenal steroids [1]. - This would lead to severe **adrenal insufficiency**, **hypotension**, and **salt-wasting**, with a lack of androgenization due to impaired sex steroid synthesis [1].

Q: Which of the following is NOT a feature of Autoimmune Polyglandular Syndrome type 1 (APS-1)?

Autoimmune thyroiditis. ### Autoimmune thyroiditis - **Autoimmune thyroiditis** is a key component of **Autoimmune Polyglandular Syndrome type 2 (APS-2)**, not APS-1 [1]. - APS-1 is distinguished by its classic triad, which does not include autoimmune thyroiditis as a primary feature [1]. ### Mucocutaneous candidiasis - **Chronic mucocutaneous candidiasis** is a defining feature of APS-1, affecting nearly all patients [1]. - This fungal infection is often the **first symptom** to appear in patients with APS-1. ### Addison's disease - **Addison's disease (primary adrenal insufficiency)** is a highly prevalent component of APS-1, occurring in over 80% of patients [1]. - It results from the autoimmune destruction of the adrenal cortex. ### Hypoparathyroidism - **Hypoparathyroidism** is a crucial diagnostic criterion for APS-1, occurring in over 70% of affected individuals [1]. - It leads to **hypocalcemia** due to inadequate parathyroid hormone production.

Q: Difference between thyrotoxicosis and malignant hyperthermia is -

Elevated serum CPK level. Elevated serum CPK level - **Elevated serum creatine phosphokinase (CPK)** is a hallmark of **malignant hyperthermia** due to widespread muscle breakdown, whereas it is typically normal or only mildly elevated in thyrotoxicosis. - This difference is crucial for differentiating these conditions, as **muscle rigidity** and subsequent damage are central to the pathogenesis of malignant hyperthermia. *Tachycardia* - **Tachycardia** (rapid heart rate) is a prominent feature of both **thyrotoxicosis** [1] and **malignant hyperthermia** [2] due to different physiological mechanisms. - In thyrotoxicosis, it results from increased metabolic demand and direct cardiac stimulation [1], while in malignant hyperthermia, it’s a response to increased metabolic rate and CO2 production. *Hyperthermia* - **Hyperthermia** (elevated body temperature) is a defining feature of both **thyrotoxicosis** (especially during a thyroid storm) and **malignant hyperthermia** [2]. - Its presence alone cannot differentiate between these two conditions, as the underlying cause of the fever differs significantly. *Muscle rigidity* - **Muscle rigidity** is a classic and early sign of **malignant hyperthermia**, caused by uncontrolled calcium release in muscle cells [3]. - While muscle weakness and tremors can occur in **thyrotoxicosis** [1], generalized severe muscle rigidity is not a typical feature and is crucial for distinguishing between the two.

Q: All are causes of Osteoporosis, except:

Hypothyroidism. Hypothyroidism - **Hypothyroidism** is generally associated with decreased bone turnover and can lead to **increased bone mineral density**, rather than osteoporosis. - In some cases, severe hypothyroidism might cause secondary osteoporosis due to associated **vitamin D deficiency** or other factors, but it is not a direct cause. Thyrotoxicosis - **Thyrotoxicosis** (hyperthyroidism) accelerates **bone remodeling**, leading to increased **bone resorption** and a net loss of bone mass. - This increases the risk of osteoporosis and fractures due to the catabolic effects of excess **thyroid hormone**. Old age - **Old age** is a major risk factor for osteoporosis due to a natural decline in **bone mineral density** and bone formation over time [2]. - Hormonal changes, such as **estrogen deficiency** in postmenopausal women and reduced **testosterone** in men [1], contribute significantly to age-related bone loss [2]. Chronic heparin therapy - **Chronic heparin therapy** (especially **unfractionated heparin**) can cause osteoporosis due to its effects on **osteoblast activity** and **collagen synthesis**. - It interferes with **bone formation** and can enhance **bone resorption**, leading to a decrease in bone density.

Q: Secondary hyperparathyroidism due to Vit D deficiency shows :

Hypocalcemia. ***Hypocalcemia*** - **Vitamin D deficiency** leads to decreased intestinal absorption of calcium, causing **hypocalcemia** [3]. - This persistent **low serum calcium** is the primary stimulus for the parathyroid glands to increase PTH secretion, leading to secondary hyperparathyroidism [1], [2]. *Hypophosphatemia* - While PTH typically promotes phosphate excretion in the kidneys leading to hypophosphatemia, in **secondary hyperparathyroidism due to vitamin D deficiency**, the effect on phosphate can be variable [3]. - The goal of increased PTH is to raise calcium, and maintaining some level of phosphate is necessary for bone health and proper calcium regulation. Early or mild deficiency may not show significant hypophosphatemia. *Hypercalcemia* - **Hypercalcemia** is a characteristic feature of **primary hyperparathyroidism**, where the parathyroid glands autonomously overproduce PTH [1]. - In secondary hyperparathyroidism (due to vitamin D deficiency), the PTH is elevated in response to **low calcium**, and sustained significant hypercalcemia is not expected; in fact, the underlying problem is **hypocalcemia** [1]. *Hyperphosphatemia* - **PTH** generally acts to lower serum phosphate levels by promoting its renal excretion [2]. - Therefore, **hyperphosphatemia** is not typically observed in secondary hyperparathyroidism; rather, a more common finding would be normal or low phosphate due to the elevated PTH [3].

Q: A 48 year-old woman underwent subtotal thyroidectomy. She has a vague family history of malignant hyperthermia. She develops agitation, restlessness, fever, tremor, shivering, and tachypnea. Thyrotoxic crises can be best distinguished from malignant hyperthermia by estimating -

Muscular rigidity. ***Muscular rigidity*** - **Malignant hyperthermia** is characterized by severe **muscle rigidity** due to uncontrolled calcium release from the sarcoplasmic reticulum, which is typically absent in thyrotoxic crisis. - This rigidity, especially of the **jaw and limb muscles**, is a cardinal and specific differentiating sign for malignant hyperthermia [2]. *Increased CPK levels* - While both conditions can cause elevated **creatine phosphokinase (CPK)**, the increase is usually far more pronounced and rapid in malignant hyperthermia due to widespread muscle breakdown. - However, CPK elevation can occur in severe thyrotoxicosis due to metabolic stress, making it less specific as a primary differentiating factor. *LDH* - **Lactate dehydrogenase (LDH)** can be elevated in both conditions due to cellular damage and increased metabolic activity. - This elevation is a non-specific marker of tissue injury and does not reliably distinguish between thyrotoxic crisis and malignant hyperthermia. *Temperature variation* - Both conditions present with **hyperthermia** and significantly elevated body temperatures [1]. - While the rapidity and degree of temperature rise can vary, it is not a consistently reliable distinguishing feature in isolation because both can manifest extremely high fevers.

Q: Patchy hair loss with hyperhidrosis of skin points to the diagnosis of -

Hyperthyroidism. ***Hyperthyroidism*** - **Hyperthyroidism** can cause **diffuse hair thinning** or **patchy hair loss**, and increased **sweating (hyperhidrosis)** is a classic symptom due to increased metabolic rate [1]. - Other common symptoms include **heat intolerance**, **tachycardia**, **weight loss**, and **tremors**. *Alopecia areata* - Characterized by **well-demarcated, smooth non-scarring patches of hair loss**, often with **exclamation mark hairs** [1]. - It is an **autoimmune condition** and typically does not present with hyperhidrosis as a primary symptom. *Trichotillomania* - Defined by the **compulsive pulling out of one's hair**, leading to **irregular patches of hair loss** with hairs of varying lengths [1]. - It is a **psychiatric disorder** and does not cause hyperhidrosis. *Adenoma sebaceum* - This term is a misnomer for **facial angiofibromas**, which are small, red-to-flesh-colored papules typically found on the nose and cheeks. - These lesions are a common feature of **Tuberous Sclerosis Complex** and do not cause hair loss or hyperhidrosis.

Question 1

A 14-year-old male presents with type I diabetes mellitus. His mother wants to know if the boy's brother might also have an increased risk of getting the disease. Which of the following genotypes, if present in the brother, would be associated with the greatest risk of developing diabetes?

Accepted Answer

DR3/DR4

Answer

DR2/DR4

Answer

DR2/DR2

Answer

B27/B27

Question 2

What is the characteristic hormone pattern in hypergonadotropic hypogonadism?

Accepted Answer

Increase FSH increase LH

Answer

Decrease FSH and increase LH

Answer

Decrease FSH and LH

Answer

Increase FSH decrease LH

Question 3

Hypertension with androgenization of a female child is a feature of congenital adrenal hyperplasia due to deficiency of:

Accepted Answer

C-11 hydroxylase

Answer

C-17 hydroxylase

Answer

C-21 hydroxylase

Answer

Desmolase

Question 4

Which of the following is NOT a feature of Autoimmune Polyglandular Syndrome type 1 (APS-1)?

Accepted Answer

Autoimmune thyroiditis

Answer

Mucocutaneous candidiasis

Answer

Addison's disease

Answer

Hypoparathyroidism

Question 5

Difference between thyrotoxicosis and malignant hyperthermia is -

Accepted Answer

Elevated serum CPK level

Answer

Tachycardia

Answer

Hyperthermia

Answer

Muscle rigidity

Question 6

The most common presentation of hyperparathyroidism beyond the neonatal period is –

Accepted Answer

Stones, bones, abdominal groans, thrones and psychiatric overtones

Answer

Bronchospasm

Answer

Seizure

Answer

Syncope secondary to prolonged QT intervals

Question 7

All are causes of Osteoporosis, except:

Accepted Answer

Hypothyroidism

Answer

Thyrotoxicosis

Answer

Old age

Answer

Chronic heparin therapy

Question 8

Secondary hyperparathyroidism due to Vit D deficiency shows :

Accepted Answer

Hypocalcemia

Answer

Hypophosphatemia

Answer

Hypercalcemia

Answer

Hyperphosphatemia

Question 9

A 48 year-old woman underwent subtotal thyroidectomy. She has a vague family history of malignant hyperthermia. She develops agitation, restlessness, fever, tremor, shivering, and tachypnea. Thyrotoxic crises can be best distinguished from malignant hyperthermia by estimating -

Accepted Answer

Muscular rigidity

Answer

Increased CPK levels

Answer

LDH

Answer

Temperature variation

Question 10

Patchy hair loss with hyperhidrosis of skin points to the diagnosis of -

Accepted Answer

Hyperthyroidism

Answer

Alopecia areata

Answer

Trichotillomania

Answer

Adenoma sebaceum

Endocrinology — MCQs

Endocrinology — MCQs

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