All of the following are criteria of a substance used for GFR measurement, except?

Correct Answer: D

Rationale: A substance for GFR measurement, like inulin, must be freely filtered, not secreted (A) or reabsorbed (B) by tubules, and non-toxic (C) to ensure clearance equals GFR. It should not be metabolized (D), as metabolism alters its concentration, invalidating the measurement. Thus, ‘should be metabolized' is not a criterion, making D correct.

Correct Answer: B

Rationale: Carbonic acid ([H₂CO₃]) in blood is very low (~0.001 mM) and unstable, rapidly dissociating into CO₂ and H₂O, making direct measurement difficult. It's estimated via PCO₂ (0.03 × PCO₂ in Henderson-Hasselbalch). It remains effective in the bicarbonate buffer equation (C is false), and no replacement is needed (D), making B correct.

Correct Answer: D

Rationale: The evaluation phase of the nursing process involves reassessment and audit (D) to determine if outcomes were met, adjusting care as needed. Data collection (A) is assessment, decision-making (B) and priority-setting (C) occur in planning, making D the primary evaluation action.

Correct Answer: C

Rationale: The kidneys regulate acid-base balance by excreting H⁺ and reabsorbing HCO₃⁻ (opposite of C), making this statement incorrect and needing education. Filtration (A), reabsorption (B), and secretion (D) are accurate, highlighting C as the error.

Correct Answer: D

Rationale: The thick ascending loop creates the medullary gradient (A), urine entering the collecting duct is hypotonic post-dilution (B), and without ADH, water isn't reabsorbed, keeping urine dilute (C). All are true—gradient drives concentration, urine starts hypotonic, ADH is key—making E (all are correct), reassigned as D, correct.