Endocrinology Exam Questions

Correct Answer: B

Rationale: Karyotype 47, XYY refers to the presence of an extra Y chromosome in males. This condition is known as XYY syndrome, also called Jacob's syndrome. Individuals with XYY syndrome are typically phenotypically male but may have some associated physical and behavioral characteristics. These individuals are often referred to as "supermales" due to the presence of the extra Y chromosome. This is different from true hermaphroditism, Klinefelter's syndrome, and gonadal dysgenesis, which have distinct chromosomal patterns and manifestations.

Correct Answer: D

Rationale: The most common cause of Cushing's syndrome is a pituitary adenoma, specifically a corticotroph adenoma. This adenoma leads to excessive secretion of adrenocorticotropic hormone (ACTH) by the pituitary gland, which in turn stimulates the adrenal glands to produce high levels of cortisol. This results in the symptoms and signs characteristic of Cushing's syndrome. Pituitary adenomas are responsible for around 70-80% of cases of Cushing's syndrome, making it the most common cause.

Correct Answer: B

Rationale: Hashimoto's thyroiditis is an autoimmune disease where the immune system mistakenly attacks the thyroid gland. The antibodies produced by the immune system target the thyroglobulin in the thyroid gland, leading to its destruction over time. This results in decreased thyroid hormone production, leading to hypothyroidism. Therefore, choice B, "A destructive autoimmune disease caused by auto-reactive antibodies against thyroglobulin," best describes Hashimoto's thyroiditis.

Correct Answer: B

Rationale: Myxoedema refers to severe hypothyroidism which can lead to neurological manifestations. The correct features associated with myxoedema include delayed relaxation of ankle jerk (Choice A), hypertonia (Choice C), and bradylalia (Choice D). Cerebellar ataxia, which involves incoordination and balance issues due to dysfunction of the cerebellum, is not a typical neurological feature seen in myxoedema.

Correct Answer: D

Rationale: Addison's disease, also known as primary adrenal insufficiency, is mainly caused by the autoimmune destruction of the adrenal cortex. This results in the inadequate production of hormones such as cortisol and aldosterone by the adrenal glands. While other conditions such as Adrenoleukodystrophy, Pyelonephritis, and Tuberculosis can also affect the adrenal glands, they are not known to be direct causes of Addison's disease.