Correct Answer: C

Rationale: Rationale for Correct Answer (C): Elevated T and T3/T4 levels are indicative of primary hypothyroidism, such as myxedema. In this case, the patient presents with classic symptoms of hypothyroidism, including altered mental status, hypothermia, and heart failure. Elevated T3/T4 levels confirm the diagnosis. Summary of Incorrect Choices: A: Elevated adrenocorticotropic hormone is associated with adrenal disorders, not hypothyroidism. B: Elevated cortisol levels suggest Cushing's syndrome, a condition of excess cortisol production, not hypothyroidism. D: Elevated thyroid-stimulating hormone is seen in primary hypothyroidism, but in myxedema, the issue is not with TSH but with T3/T4 levels.

Correct Answer: D

Rationale: The correct answer is D because continuous venovenous hemodiafiltration (CVVHDF) combines ultrafiltration, convection, and dialysis to maximize fluid and solute removal. Ultrafiltration removes plasma water, convection removes fluids and solutes, and dialysis facilitates solute removal through diffusion. Choice A is incorrect because convection alone does not remove solutes, but CVVHDF combines convection with other methods. Choice B is incorrect because CVVHDF is not specifically used for volume overload, although it does remove fluids. Choice C is incorrect because CVVHDF does not involve adding dialysate to remove solutes; instead, it relies on diffusion for solute removal. In summary, the correct answer D is the best choice as it encompasses all the components needed for comprehensive fluid and solute removal in CVVHDF.

Correct Answer: C

Rationale: Rationale: Acute tubular necrosis (ATN) is the most common intrarenal condition causing acute kidney injury. ATN is characterized by damage to the renal tubules due to ischemia or nephrotoxic substances. Prolonged ischemia (choice A) and exposure to nephrotoxic substances (choice B) can lead to ATN. Hypotension for several hours (choice D) can result in ischemic injury, which may lead to ATN but is not the direct cause. Therefore, choice C is correct as it directly relates to the primary intrarenal condition of ATN.

Correct Answer: C

Rationale: Step 1: Syndrome of inappropriate antidiuretic hormone (SIADH) leads to excess water retention, diluting sodium levels in the blood. Step 2: Fluid restriction is the mainstay of treatment to prevent further dilution of sodium. Step 3: Administering 3% normal saline (choice A) can worsen the condition by further increasing sodium levels. Step 4: Exogenous vasopressin (choice B) would exacerbate the problem by increasing water retention. Step 5: Low sodium diet (choice D) may be beneficial in the long term but is not the immediate priority.

Correct Answer: A

Rationale: The correct answer is A: Kidney, ureter, bladder (KUB) x-ray. KUB x-ray is a noninvasive diagnostic procedure that provides information about the size, shape, and position of the kidneys, ureters, and bladder. It can help detect abnormalities such as kidney stones or structural issues. Rationale: 1. KUB x-ray is noninvasive, meaning it does not require any incisions or insertion of instruments into the body. 2. It is commonly used as an initial screening tool to assess kidney function. 3. Renal ultrasound (Choice B) is also noninvasive but primarily used for imaging the kidneys and not the entire urinary system. 4. MRI (Choice C) and IVP (Choice D) are more invasive procedures that involve injecting contrast agents and may not be routinely used for initial kidney function assessment. In summary, the KUB x-ray is the correct choice as it is a noninvasive procedure specifically designed to evaluate kidney