Nokea
Which of the following are causes of nephrogenic diabetes insipidus?
- A. Sheehan's syndrome
- B. Lithium
- C. Mutations in the vasopressin (ADH) receptor gene
- D. Mutations in vasopressin gene
Correct Answer: B
Rationale: Nephrogenic diabetes insipidus (NDI) is a condition where the kidneys are unable to respond to antidiuretic hormone (ADH) as they should, leading to excessive urination and extreme thirst. One of the main causes of nephrogenic diabetes insipidus is the use of certain medications, with lithium being the most common culprit. Lithium can interfere with the kidney's response to ADH, resulting in decreased water reabsorption and the characteristic symptoms of diabetes insipidus. Other causes of NDI can include genetic mutations affecting the vasopressin receptor gene or other underlying conditions such as hypercalcemia, hypokalemia, or obstructive uropathy.
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What is Addison's disease?
- A. Addison's disease is a long-term endocrine disorder in which the adrenal glands do not produce enough steroid hormones.
- B. Addison's disease involves the overproduction of cortisol and aldosterone by the adrenal cortex.
- C. Addison's disease involves the overproduction of androgens by the adrenal medulla.
- D. Addison's disease involves the underproduction of androgens by the adrenal medulla.
Correct Answer: A
Rationale: Addison's disease, also known as primary adrenal insufficiency, is a condition where the adrenal glands do not produce enough steroid hormones, mainly cortisol and sometimes aldosterone. This deficiency in steroid hormone production is typically caused by autoimmune destruction of the adrenal cortex. Without enough cortisol and aldosterone, various symptoms may arise, such as fatigue, weight loss, low blood pressure, and skin discoloration. Therefore, option A accurately describes the nature of Addison's disease.
Myxoedema is characterized by all except:
- A. Butterfly rash in face
- B. Sinus bradycardia
- C. Solid oedema
- D. Madarosis
Correct Answer: A
Rationale: Myxoedema is a term used to describe severe hypothyroidism. The characteristic features of myxoedema include sinus bradycardia (choice B), solid oedema (choice C), and madarosis (choice D), which refers to loss of eyebrows and eyelashes. However, a butterfly rash is not a typical feature of myxoedema. A butterfly rash is commonly associated with conditions like systemic lupus erythematosus rather than myxoedema.
The receptors for non-steroid peptide hormones are found on the ______.
- A. plasma membrane
- B. nuclear envelope
- C. mitochondria
- D. lysosomes
Correct Answer: A
Rationale: The receptors for non-steroid peptide hormones are typically found on the plasma membrane of target cells. These hormones are large or polar molecules that cannot easily diffuse through the cell membrane. Instead, they bind to specific receptors on the cell surface, initiating signaling pathways that eventually lead to changes within the cell. Once the peptide hormone binds to its receptor on the plasma membrane, secondary messenger systems are activated to relay the signal into the cell and initiate the appropriate cellular response. This distinct mechanism of action highlights the importance of the plasma membrane as the location of receptors for non-steroid peptide hormones.
In a patient with centripetal obesity, acne and hirsutism. The most likely diagnosis is:
- A. Cushing's syndrome
- B. Diabetes mellitus
- C. Hypogonadism
- D. Hypothyroidism
Correct Answer: A
Rationale: Centripetal obesity, acne, and hirsutism are classic features of Cushing's syndrome. Cushing's syndrome results from prolonged exposure to high levels of cortisol, which can be due to various causes such as adrenal tumors, pituitary adenomas, or exogenous glucocorticoid use. Centripetal obesity refers to the characteristic fat distribution pattern seen in Cushing's syndrome, where fat accumulates mainly in the face, neck, and trunk while sparing the limbs. Acne and hirsutism are also commonly seen in Cushing's syndrome due to the hormonal imbalances caused by excess cortisol. Testing for serum cortisol levels, dexamethasone suppression tests, and imaging studies can help confirm the diagnosis of Cushing's syndrome in a patient presenting with these symptoms.
All of the following are potential causes of elevated LDL , except:
- A. Cirrhosis
- B. Hypothyroidism
- C. Nephrotic syndrome
- D. Thiazide diuretics
Correct Answer: A
Rationale: Cirrhosis is not a potential cause of elevated LDL cholesterol levels. The liver plays a significant role in cholesterol metabolism, and liver disease like cirrhosis can actually lead to decreased levels of LDL cholesterol. Elevated LDL cholesterol levels can be caused by conditions such as hypothyroidism, nephrotic syndrome, or the use of certain medications like thiazide diuretics.