Nokea
Which of the following is false regarding medullary carcinoma of thyroid?
- A. Cervical Iymphadenopathy
- B. High serum calcitonin
- C. Carcinoid syndrome may be associated with
- D. Psychosis
Correct Answer: D
Rationale: Medullary carcinoma of the thyroid typically presents with symptoms related to the thyroid gland itself, neck mass or swelling, and sometimes cervical lymphadenopathy. It is characterized by the production of calcitonin, leading to high serum calcitonin levels. Carcinoid syndrome, which includes symptoms such as flushing, diarrhea, and wheezing, is more commonly associated with neuroendocrine tumors, rather than medullary carcinoma of the thyroid. Psychosis is not a typical feature or manifestation of medullary carcinoma of the thyroid.
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Blood calcium is elevated:
- A. in rickets.
- B. in pseudohypoparathyroidism.
- C. by calcitonin.
- D. by Vitamin D3
Correct Answer: D
Rationale: Blood calcium levels are primarily regulated by the actions of parathyroid hormone (PTH) and Vitamin D. Vitamin D plays a crucial role in maintaining calcium balance in the body by promoting the absorption of calcium from the intestines. When blood calcium levels are low, Vitamin D works to increase absorption of calcium to raise the levels back to normal. Therefore, elevated blood calcium levels are commonly associated with excess Vitamin D intake or conditions that increase Vitamin D levels, such as hypervitaminosis D.
Which of the following is not a neuromuscular feature of thyrotoxicosis?
- A. Myasthenic syndrome
- B. Brisk knee jerk
- C. Hypokalaemic periodic paralysis
- D. Hyperkinesia
Correct Answer: A
Rationale: Thyrotoxicosis typically presents with hypermetabolism and various neuromuscular manifestations. Myasthenic syndrome, which involves muscle weakness and fatigability, is not a common neuromuscular feature of thyrotoxicosis. Instead, manifestations such as brisk knee jerk reflexes, hypokalaemic periodic paralysis (due to shifts in potassium levels), and hyperkinesia (excessive movement) are more commonly observed in patients with thyrotoxicosis. Myasthenic syndrome is more commonly associated with autoimmune disorders affecting the neuromuscular junction, such as myasthenia gravis.
All are features of diabetic ketoacidosis except:
- A. Hyperthermia
- B. Drowsiness
- C. Dehydration
- D. Air hunger
Correct Answer: A
Rationale: Hyperthermia is not a typical feature of diabetic ketoacidosis (DKA). DKA is typically characterized by high blood sugar levels, ketone accumulation, metabolic acidosis, dehydration, drowsiness, and, in severe cases, unconsciousness. Common symptoms include drowsiness, dehydration, and air hunger (deep and rapid breathing). However, hyperthermia, which refers to an elevated body temperature, is not a characteristic typically associated with DKA. It is important to monitor and manage DKA promptly as it is a serious complication of diabetes that requires immediate medical attention.
Sheehan's syndrome presents with:
- A. Cardiac failure
- B. Persistent lactation
- C. Fever
- D. Striking cachexia
Correct Answer: B
Rationale: Sheehan's syndrome, also known as postpartum hypopituitarism, is a condition characterized by pituitary gland dysfunction due to severe blood loss during childbirth, resulting in ischemic necrosis of the pituitary gland. As a consequence of pituitary hormone deficiency, one of the hallmark manifestations of Sheehan's syndrome is persistent lactation despite stopping breastfeeding. This occurs due to inadequate prolactin inhibition, leading to continuous milk production. Other common symptoms of Sheehan's syndrome include fatigue, weight loss, menstrual irregularities, hypothyroidism, adrenal insufficiency, and other pituitary hormone deficiencies. Cardiac failure, fever, and striking cachexia are not typical presentations associated with Sheehan's syndrome.
Thyroid-stimulating hormone (TSH):
- A. is synthesized in parafollicular cells
- B. is a template for thyroid hormone biosynthesis.
- C. is derived from iodinated tyrosine residues.
- D. secretion is inhibited by TRH from the hypothalamus.
Correct Answer: D
Rationale: Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). TSH secretion is regulated by the hypothalamus via the release of thyrotropin-releasing hormone (TRH). TRH acts on the anterior pituitary gland to stimulate the production and release of TSH. Therefore, TSH secretion is indeed inhibited by TRH, not stimulated as in the other options.