Which one of the following statements about lithium is accurate?

Correct Answer: C

Rationale: Lithium, used for bipolar disorder, stabilizes mood via inositol depletion and other mechanisms. It can cause hypothyroidism, not hyperthyroidism, by inhibiting thyroid hormone release. High sodium intake increases lithium excretion, lowering plasma levels, not raising them. Common adverse effects include acne (sebaceous gland stimulation), polydipsia, and polyuria (due to nephrogenic diabetes insipidus from ADH antagonism), affecting many patients and requiring monitoring. Teratogenicity concerns focus on Ebstein's anomaly (cardiac defect), not spina bifida, though risks are low with modern management. Sedation isn't rapid; therapeutic effects take days to weeks. The constellation of acne, polydipsia, and polyuria reflects lithium's broad physiological impact, making it the most accurate description of its side effect profile.

Correct Answer: D

Rationale: Spironolactone is a potassium-sparing diuretic that works by blocking the reabsorption of sodium and water in the kidneys while retaining potassium. This mechanism can lead to an increased risk of hyperkalemia, a condition characterized by high levels of potassium in the blood. Therefore, patients taking spironolactone should be closely monitored for signs and symptoms of hyperkalemia, such as muscle weakness, fatigue, and abnormal heart rhythms. In contrast, diuretics like hydrochlorothiazide (choice A), furosemide (choice B), and acetazolamide (choice C) are not typically associated with the risk of hyperkalemia.

Correct Answer: D

Rationale: The patient's chronic springtime symptoms-itchy, watery eyes, and runny nose-point to seasonal allergic rhinitis, a histamine-driven condition. Albuterol is a bronchodilator for asthma, not allergies. Diphenhydramine is an H1 antihistamine, effective but sedating, which may not suit an active steamroller operator. Epinephrine is for acute anaphylaxis, not chronic allergies. Hydroxyzine is another sedating antihistamine, less ideal for daily use. Loratadine (E), a non-sedating H1 antihistamine, effectively blocks histamine receptors, relieving symptoms without drowsiness, making it the most appropriate choice. Given his occupation and chronicity, a non-sedating option is critical for safety and compliance. Loratadine's long-acting, once-daily dosing also fits his reluctance to seek medical care, offering convenience and efficacy. The rationale prioritizes a treatment balancing symptom relief with minimal impact on his daily function, ruling out sedating or irrelevant options.

Correct Answer: D

Rationale: Luteinizing hormone (LH) from the pituitary stimulates testosterone production in testicular Leydig cells, its primary role in men, driving male physiology. Sperm production is regulated by FSH, not LH. Secondary sex characteristics and sex organ growth depend on testosterone, which LH indirectly supports by controlling its synthesis, not directly managing. Testosterone regulation is LH's specific function, triggering steroidogenesis, essential for fertility and masculinity, distinct from FSH's gamete role.

Correct Answer: B

Rationale: Cocaine is unique among local anesthetics because it undergoes metabolism by plasma esterases, unlike other local anesthetics which are typically metabolized by the liver. This rapid metabolism by plasma esterases contributes to its short duration of action as a local anesthetic. This property of cocaine also contributes to its potential for systemic toxicity and drug interactions, making it important to consider when using cocaine in a clinical setting.