A nurse caring for a patient with neurological impairment often must use painful stimuli to pressure. She neither slaps the patient nor pinches the nipple to elicit a response to pain. In this scenario, the nurse is exemplifying the ethical principle of

Rationale:
A. Innate immunity is incorrect because it provides immediate, non-specific defense against pathogens and does not involve antibody production. Examples include physical barriers like skin, phagocytic cells, and inflammatory responses.

B. Autoimmune response is incorrect because this occurs when the immune system attacks the body’s own cells, rather than responding to a foreign antigen introduced by a vaccine.

C. Humoral immunity is correct because it involves B lymphocytes (B cells) and plasma cells producing antibodies that circulate in the blood and lymph to neutralize specific antigens. Vaccines stimulate this adaptive immune response, creating immunologic memory for future protection.

D. Cell-mediated immunity is incorrect because this arm of the immune system involves T lymphocytes that directly attack infected or abnormal cells, rather than producing antibodies. It is important for fighting viruses, intracellular pathogens, and tumor cells.

Rationale:
A. Fatigue is incorrect because, although patients with diabetes insipidus (DI) may experience fatigue, this symptom is nonspecific. Fatigue can result from many conditions, including dehydration, electrolyte imbalances, chronic illness, or sleep disturbances. In DI, fatigue may develop secondary to fluid and electrolyte loss, but it is not a primary or diagnostic feature of the disorder.

B. Polydipsia is correct because it is the most indicative and classic symptom of DI. Diabetes insipidus results from either a deficiency of antidiuretic hormone (ADH, also called vasopressin) in central DI or the kidneys’ inability to respond to ADH in nephrogenic DI. Without adequate ADH activity, the kidneys cannot concentrate urine, leading to the excretion of large volumes of dilute urine (polyuria), sometimes up to 3–20 liters per day in severe cases. The body attempts to compensate for this fluid loss by triggering intense thirst (polydipsia), often resulting in the patient drinking large amounts of water to prevent dehydration. Polydipsia is thus a hallmark symptom and a key diagnostic clue for DI.

C. Weight gain is incorrect because the fluid loss associated with DI typically causes weight loss rather than gain. Patients may have decreased body mass due to the ongoing loss of water and potential electrolyte depletion. Weight gain is not associated with DI unless there is excessive water intake beyond renal capacity, which is uncommon.

D. Diarrhea is incorrect because DI affects renal water reabsorption, not gastrointestinal function. Diarrhea is unrelated to the pathophysiology of DI and may indicate a separate gastrointestinal issue rather than the endocrine disorder itself.