Endo Hypthal Pitu Phys Pharm MCQ's

The patient's symptoms of continuous thirst and polyuria, along with undetectable plasma ADH levels and low urine osmolality, suggest a diagnosis of central diabetes insipidus. Desmopressin is a synthetic form of ADH and would be appropriate for this patient to replace the deficient hormone and alleviate her symptoms. Hydrochlorothiazide, Amiloride, Carbamazepine, and Chlorpropamide are not indicated for central diabetes insipidus.

The correct answer is D. The explanation is that the hypothalamus releases releasing factors that travel through the bloodstream to the anterior pituitary gland, where they stimulate the release of specific hormones. This is known as the hypothalamic-pituitary portal system. On the other hand, the hypothalamus directly sends axonal connections to the posterior pituitary gland, allowing it to release hormones such as oxytocin and vasopressin. Therefore, D correctly lists the type of connections between the hypothalamus and the anterior and posterior pituitary glands.

Bromocriptine relieves symptoms of hyperprolactinemia in a patient with prolactin-secreting pituitary adenoma by stimulating dopamine receptors. This medication is a dopamine agonist, which means it binds to and activates dopamine receptors in the brain. By stimulating these receptors, bromocriptine inhibits the release of prolactin from the pituitary gland, thereby reducing the levels of this hormone in the body. This helps alleviate the symptoms associated with hyperprolactinemia, such as irregular menstrual periods, infertility, and breast milk production in non-pregnant women.

Octreotide is a synthetic analogue of somatostatin, a hormone that inhibits the release of growth hormone. The patient's symptoms, such as joint pain, headache, excessive sweating, deepening of the voice, protrusion of the jaw, enlargement of the hands, thickening of the skin, and a barrel chest, are consistent with acromegaly, which is caused by excessive growth hormone secretion. The presence of a pituitary adenoma further supports this diagnosis. Octreotide would be prescribed to help control the symptoms of acromegaly while waiting for radiotherapy to work on reducing the size of the adenoma and decreasing growth hormone secretion.

The most likely defect in this individual to explain his dwarfism is the inability of the liver to produce IGF-1. This is supported by the extremely low plasma IGF-1 levels found in the laboratory tests. IGF-1 is a hormone that is stimulated by GH and is responsible for the growth-promoting effects of GH. In this case, the high plasma GH levels indicate that GH production is not the issue, but rather the liver's inability to produce IGF-1 is preventing the growth-promoting effects of GH.

Desmopressin is a synthetic form of vasopressin, also known as antidiuretic hormone (ADH). It acts by stimulating V2 receptors in the renal collecting ducts, which leads to increased reabsorption of water and reduced urine production. This helps to alleviate the symptoms of excessive thirst and urination in patients with neurogenic diabetes insipidus.

When a tumor is present in the anterior pituitary, it can disrupt the normal secretion of hormones. In this case, the tumor causes a decrease in ACTH secretion. ACTH is responsible for stimulating the release of cortisol from the adrenal glands. Therefore, with decreased ACTH levels, there will be a decrease in cortisol secretion. However, the tumor can also lead to an increase in the production of CRH (corticotropin-releasing hormone) by the hypothalamus, which stimulates the release of ACTH. Therefore, the plasma levels of hormones in this scenario would be increased CRH, decreased ACTH, and decreased cortisol.

The correct answer is Prolactin (Prl). Prolactin is a hormone produced by the pituitary gland that is responsible for stimulating milk production in the breasts. In this case, the woman's symptoms, such as the absence of menstrual cycle, weight gain, fatigue, and the presence of a white crystalline deposit around her nipples, suggest that she may be experiencing hyperprolactinemia, which is an elevated level of prolactin in the blood. This condition can be caused by head trauma, such as the accident she experienced, and can lead to disruptions in the menstrual cycle and other symptoms described.

Pegvisomant is the correct answer because it acts by blocking receptors for growth hormone. This drug is used for treating acromegaly, a condition characterized by excessive growth hormone production. By blocking the growth hormone receptors, pegvisomant helps to reduce the effects of the excess hormone in the body. It does not stimulate the production or release of growth hormone, but instead directly inhibits its action.

IGF-1 is considered to act as a paracrine signaling factor in most tissues. Paracrine signaling occurs when a cell secretes a signal molecule that acts on nearby cells, influencing their behavior or function. In the case of IGF-1, it is produced by various tissues and acts on neighboring cells to regulate processes such as cell growth, proliferation, and differentiation. This localized signaling allows for precise control and coordination of cellular activities within a specific tissue or organ.

The most likely explanation for the patient's polyuria is that the magnocellular neurons of the Para ventricular and suproptic nuclei of the hypothalamus are not responding to an increase in whole body osmolarity and are not releasing vasopressin from the posterior pituitary. Vasopressin, also known as antidiuretic hormone (ADH), is responsible for regulating water balance in the body by controlling the reabsorption of water in the kidneys. In this case, the lack of response from the hypothalamus leads to a decrease in vasopressin release, resulting in excessive urine production and polyuria.

Given the man's signs and symptoms of postural hypotension, unusual fatigue, lightheadedness, darker-than-usual complexion, and hyponatremia, hyperkalemia, and hypocalcemia, it is likely that there is a dysfunction in the adrenal glands. The adrenal glands are responsible for the production of cortisol, which helps regulate blood pressure and electrolyte balance. In this case, the most likely combination of hormone secretion would be hypersecretion of CRH, hypersecretion of ACTH, and hyposecretion of cortisol. Hypersecretion of CRH and ACTH would lead to increased stimulation of the adrenal glands, resulting in increased production of cortisol. However, the hyposecretion of cortisol would lead to the symptoms observed in the patient.

When the man fails to adequately compensate for the nutritional content of dairy products in his former diet, his intake of calcium drops dramatically. The hormone 1,25-dihyroxycholecalciferol, also known as active vitamin D, plays a crucial role in maintaining plasma calcium levels. It promotes the absorption of calcium from the intestines and reabsorption of calcium from the kidneys, ensuring that enough calcium is available in the bloodstream. Therefore, in this situation, the direct actions of 1,25-dihyroxycholecalciferol are most important in maintaining his plasma calcium levels.

A key piece of information in the diagnostic strategy would be low plasma levels of growth hormone binding protein. Growth hormone binding protein (GHBP) is responsible for binding to growth hormone and prolonging its half-life in the bloodstream. If there are low levels of GHBP, it suggests that there is a dysfunction in the binding of growth hormone, which could be caused by growth hormone receptor dysfunction. This information would support the hypothesis that the patient's dwarfism is caused by growth hormone receptor dysfunction rather than pituitary dysfunction.