Which of the following is not associated with hypothyroidism?

Correct Answer: B

Rationale: The correct answer is B: Weight loss. Hypothyroidism is characterized by an underactive thyroid gland, leading to a decreased metabolic rate. This typically results in weight gain, not weight loss. Choices A, C, and D are all associated with hypothyroidism. Loss of libido can occur due to hormonal imbalances, cardiac failure can result from the decreased metabolic rate affecting the heart, and organic psychosis can be a symptom of severe untreated hypothyroidism.

Correct Answer: C

Rationale: The correct answer is C: Oxytocin. The anterior pituitary gland produces several hormones, including adrenocorticotropic hormone (A), growth hormone (B), and thyroid-stimulating hormone (D). Oxytocin is actually produced by the posterior pituitary gland, not the anterior pituitary. Oxytocin is responsible for uterine contractions during childbirth and milk ejection during breastfeeding. Therefore, C is the correct answer as it is not produced by the anterior pituitary unlike the other hormones mentioned.

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: D

Rationale: The correct answer is D: second messengers. Protein hormones typically bind to cell surface receptors, activating second messenger systems to relay the signal inside the cell. This mechanism allows for rapid and amplified cellular responses. Choices A and B (cytoplasmic and nuclear receptors) are more commonly associated with steroid hormones, not protein hormones. Choice C (cyclic ribosomal adenosine phosphate) is not a known mechanism of hormone action. Thus, the correct answer is D, as second messengers are the primary mediators of protein hormone actions.

Correct Answer: B

Rationale: The correct answer is B: Cretinism. Cretinism is the most common cause of preventable mental deficiency worldwide due to severe iodine deficiency during pregnancy. Iodine is crucial for thyroid hormone production, which is essential for fetal brain development. Beriberi disease (A) is caused by thiamine deficiency and affects the nervous system, not mental deficiency. Folate deficiency (C) can cause neural tube defects but not mental deficiency. Vitamin A deficiency (D) can lead to blindness and immune system issues, but not the most common cause of preventable mental deficiency.

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: A

Rationale: The correct answer is A. Visual changes such as double vision, reduced vision, tunnel vision are common symptoms of acromegaly due to the enlargement of tissues in the eye sockets affecting the optic nerve. Paresthesia and weakness in the hands (B) are not typical symptoms of acromegaly but may be seen in conditions affecting the peripheral nerves. Diarrhoea (C) and abdominal distention (D) are not associated with acromegaly but may be seen in gastrointestinal disorders.

Correct Answer: D

Rationale: The correct answer is D because oxytocin and anti-diuretic hormone are synthesized in the hypothalamus and stored in the posterior pituitary gland before being released into the bloodstream. This process is essential for regulating various physiological functions. Choices A and C are incorrect as oxytocin and anti-diuretic hormone are not complex steroids and are not released from the anterior pituitary. Choice B is also incorrect because while these hormones are indeed synthesized in the posterior pituitary, they are stored in the posterior pituitary before their release.

Correct Answer: C

Rationale: Leydig cells are found in the testes and are responsible for producing testosterone, a crucial male sex hormone. This hormone is essential for the development of male reproductive organs, secondary sexual characteristics, and sperm production. Oestrogen is primarily produced by the ovaries in females. Androgen binding globulin is a protein that binds to testosterone in the bloodstream but is not produced by Leydig cells. Semen is produced by the accessory glands in the male reproductive system, not by Leydig cells. Therefore, the correct answer is C: Testosterone.