Molecules that can react with antibodies but cannot induce an immune reaction by themselves are called:

Correct Answer: C

Rationale: The correct answer is C: Haptens. Haptens are molecules that can react with antibodies but cannot induce an immune response on their own. They need to bind to a larger carrier molecule to trigger an immune reaction. Antigens (A) are molecules that can induce an immune response. Immunoglobulins (B) are antibodies produced by the immune system. Immunogens (D) are substances capable of inducing an immune response by themselves. Therefore, haptens best fit the description provided in the question.

Correct Answer: C

Rationale: The correct answer is C: Bone marrow suppression. Sulfonamides are known to cause hematologic adverse effects, such as bone marrow suppression leading to decreased production of blood cells. This can manifest as anemia, leukopenia, or thrombocytopenia. Monitoring for signs and symptoms of bone marrow suppression, such as fatigue, pallor, easy bruising, and increased susceptibility to infections, is crucial. Explanation of other choices: A: Ototoxicity - Sulfonamides do not typically cause ototoxicity. B: Nephrotoxicity - While sulfonamides can cause kidney damage in some cases, bone marrow suppression is a more common adverse effect. D: Increased white blood cell (WBC) count - Sulfonamides do not typically lead to an increase in WBC count; instead, they are more likely to cause a decrease due to bone marrow suppression.

Correct Answer: C

Rationale: The correct answer is C: Failure to cleave von Willebrand factor multimers. This patient's presentation is consistent with thrombotic thrombocytopenic purpura (TTP), caused by a deficiency of ADAMTS13 leading to the accumulation of ultra-large von Willebrand factor multimers. This results in platelet aggregation, microthrombi formation, hemolytic anemia, and renal failure. A is incorrect because DIC typically presents with bleeding manifestations. B is incorrect as antiplatelet antibodies would not lead to the specific findings in this case. D is incorrect as verotoxin-induced endothelial damage is associated with hemolytic uremic syndrome, which typically presents with bloody diarrhea.

Correct Answer: D

Rationale: The correct answer is D: Cystoscopy and retrograde pyelography. This is the most useful test for evaluating painless hematuria in a 65-year-old smoker. Cystoscopy allows direct visualization of the bladder and can identify potential sources of bleeding. Retrograde pyelography helps assess the upper urinary tract for any abnormalities. The other choices are not as relevant in this context: A (urine culture) is used for diagnosing urinary tract infections, B (PSA) is for prostate cancer screening, and C (bladder scan) is used for assessing bladder volume, not for evaluating hematuria.

Correct Answer: B

Rationale: The correct answer is B: Myeloproliferative syndrome. Given the patient's symptoms (fatigue, itching, splenomegaly) and lab results (elevated Hb and platelets), it suggests an overproduction of blood cells, characteristic of myeloproliferative syndromes. Myelodysplastic syndrome (choice A) presents with cytopenias, not elevated blood counts. Paraneoplastic syndrome (choice C) is associated with malignancies, not blood disorders. Cushing syndrome (choice D) is characterized by hypercortisolism, not blood abnormalities.