All of the following are associated with increased levels of total T4 in the plasma with a normal free T4 except:

Correct Answer: A

Rationale: The correct answer is A: Cirrhosis. In cirrhosis, there is a decrease in the binding proteins for T4, leading to decreased total T4 levels in the plasma. Pregnancy, euthyroid sick syndrome, and familial excess thyroid binding globulin are all conditions associated with increased total T4 levels due to various physiological changes. In pregnancy, there is an increase in thyroid hormone production to support fetal development. Euthyroid sick syndrome is a condition where there is a decrease in binding proteins, leading to an increase in free T4 levels but normal total T4 levels. Familial excess thyroid binding globulin causes an increase in total T4 levels due to excessive binding proteins.

Correct Answer: A

Rationale: The correct answer is A: Adrenaline. In injury to the adrenal cortex, adrenaline is least affected because it is primarily synthesized and secreted by the adrenal medulla, not the adrenal cortex. Cortisol, aldosterone, and androstenedione are hormones produced by the adrenal cortex. In adrenal cortex injury, the secretion of cortisol, aldosterone, and androstenedione would be significantly affected due to the damage to the adrenal cortex, leading to hormonal imbalance and related symptoms. Therefore, option A is the correct answer as it is not primarily secreted by the adrenal cortex and would be least affected in this scenario.

Correct Answer: A

Rationale: The correct answer is A because Klinefelter's syndrome is characterized by small, soft testes due to the presence of an extra X chromosome (47, XXY). This leads to hypogonadism and inadequate testosterone production, resulting in underdeveloped testes. Choice B (46, XO) is incorrect as it refers to Turner syndrome. Choice C (upper segment> lower segment) is unrelated to Klinefelter's syndrome. Choice D (Gynaecomastia) is a symptom of Klinefelter's syndrome but not the defining characteristic.

Correct Answer: B

Rationale: Thyroid acropathy, also known as thyroid dermopathy, is a skin condition commonly associated with Graves' disease. This autoimmune disorder causes an overactive thyroid gland, leading to high levels of thyroid hormones in the blood. The excess thyroid hormones can trigger changes in the skin, resulting in thyroid acropathy. Subclinical hypothyroidism (choice A) is characterized by slightly elevated TSH levels with normal thyroid hormone levels, not typically associated with thyroid acropathy. Myxoedema (choice C) refers to severe hypothyroidism and is not linked to thyroid acropathy. Medullary carcinoma of the thyroid (choice D) is a type of thyroid cancer and is not known to cause thyroid acropathy. Therefore, the correct answer is B, Graves' disease, as it is the most common condition associated with thyroid acropathy.

Correct Answer: D

Rationale: Step-by-step rationale: 1. Gynaecomastia is a known side effect of spironolactone, digitalis, and cimetidine. 2. Rifampicin is not associated with gynaecomastia. 3. Rifampicin is an antibiotic used to treat tuberculosis and other infections. 4. The mechanism of action of rifampicin does not involve hormonal changes that could lead to gynaecomastia. Summary of incorrect choices: - A: Spironolactone is a potassium-sparing diuretic that can cause gynaecomastia. - B: Digitalis (digoxin) can lead to gynaecomastia as a side effect. - C: Cimetidine, an H2 receptor antagonist, is also known to cause gynaecomastia.

Correct Answer: C

Rationale: Rationale for choice C (FSH) being correct: 1. FSH stimulates Sertoli cells in the testes. 2. Sertoli cells produce androgen binding globulin (ABG). 3. ABG binds to testosterone, regulating its availability. 4. FSH indirectly influences testosterone levels via ABG production. Summary of incorrect choices: A. LH stimulates Leydig cells to produce testosterone, not Sertoli cells. B. GnRH regulates the release of FSH and LH but does not directly stimulate ABG production. D. Oxytocin is not involved in the regulation of Sertoli cells or ABG production in males.

Correct Answer: C

Rationale: Rationale: 1. GnRH directly binds to pituitary receptors. 2. GnRH specifically targets gonadotroph cells to release LH and FSH. 3. CRH and ACTH are related to stress and adrenal function, not reproductive hormones. 4. Tremor is unrelated to pituitary hormone regulation. Summary: Gonadotrophin releasing hormone (GnRH) is the correct answer as it directly stimulates the release of LH and FSH from the pituitary gland. Other choices are incorrect as they are not involved in the regulation of reproductive hormones.

Correct Answer: B

Rationale: The correct answer is B: Intranasal vasopressin may be helpful. In diabetes insipidus, there is a deficiency of vasopressin leading to excessive urination and thirst. Administering vasopressin intranasally can help replace the deficient hormone, reducing urine output and thirst. Hypernatremia (choice A) can occur due to excessive water loss, but it is not always present. There is no osmolar gap (choice C) in diabetes insipidus. Urine specific gravity (choice D) is typically low in diabetes insipidus due to the dilute urine produced.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Anorexia nervosa can affect both males and females. 2. Therefore, it is not exclusively in females. 3. Hypokalaemia, primary amenorrhea, and low FSH and LH are commonly associated with anorexia nervosa. 4. Choice C is incorrect as anorexia nervosa can affect individuals of any gender.