Explanation: Hand hygiene (washing hands with soap and water or using an alcohol-based hand rub) is the single most important and mandatory practice to perform before and after working with *each and every* patient in a medical setting. This is the cornerstone of medical asepsis and infection control. Donning (B) and doffing (D) gloves are performed when needed for specific tasks involving potential exposure to body fluids, not necessarily for every patient interaction. Hand sanitization (C) is a component of hand hygiene but is not as comprehensive as the general term.

Explanation: Unopened insulin vials and pens should typically be stored in the refrigerator (not frozen) to maintain their potency until their expiration date. Once opened, insulin can generally be kept at room temperature for a specific period (usually 28 days, depending on the type), but long-term storage for unopened vials is refrigeration. Direct sunlight (C) or freezing (D) can damage the insulin and reduce its effectiveness. Therefore, the general manufacturer's recommendation for long-term storage is refrigeration.

Explanation: Computerized Provider Order Entry (CPOE) is a system that allows healthcare providers to directly enter medical orders (such as medications, laboratory tests, radiology orders, and consultations) into a computer system, replacing paper and verbal orders. Diagnostic tests are a key component of these orders. A problem-oriented list (B) is part of a patient's medical record. Next of kin (C) is demographic data. Follow-up appointment dates (D) are part of scheduling, not typically the order entry system.

Explanation: An electronic health record (EHR) system is designed to be accessible by multiple authorized users (e.g., doctors, nurses, medical assistants, billing staff) within a single healthcare organization and, increasingly, across different healthcare organizations through interoperability features. This allows for a comprehensive, shared view of a patient's health information. A patient portal (B) is accessed by the patient. Protected health information (PHI) (C) is the data itself, not a system. A patient health record (D) is a general term; EHR specifies the electronic, shareable system.

Explanation: Fatigue, weight gain, and thinning hair are common symptoms associated with hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormones. A Thyroid Stimulating Hormone (TSH) test is the primary screening test for thyroid dysfunction. An electrolyte panel (A) checks electrolyte balance. A urinalysis (C) examines urine for various health conditions. A blood culture (D) checks for bacterial or fungal infections in the blood.