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CCRN practice question: Endocrine, Hematology/Immunology, GI, Renal/GU, Integumentary

Endocrine, Hematology/Immunology, GI, Renal/GU, IntegumentaryDifficulty 2/5

A patient has serum sodium 118 mEq/L, serum osmolality 250 mOsm/kg, concentrated urine and no oedema. Which condition is most consistent?

  1. ADiabetes insipidus with excessive free water loss
  2. BSIADH, because water is retained while urine stays concentrated
  3. CHypovolaemic hyponatraemia from gastrointestinal losses
  4. DCerebral salt wasting with a contracted intravascular volume
Show answer and rationale

Correct: B. SIADH retains water: dilutional hyponatraemia, low serum osmolality, inappropriately concentrated urine and euvolaemia. Diabetes insipidus produces the opposite picture, and salt wasting is accompanied by volume depletion.

  • A — Diabetes insipidus causes hypernatraemia with dilute urine.
  • C — Gastrointestinal losses produce signs of volume depletion.
  • D — Cerebral salt wasting presents with hypovolaemia rather than euvolaemia.

Concept being tested

21% of the exam and the largest clinical category. Adrenal insufficiency, DI, DKA and HHS, SIADH, thyroid disorders; anemia, coagulopathies (DIC, HIT, ITP), myelosuppression, oncologic emergencies, transfusion reactions; GI hemorrhage, bowel obstruction and infarction, hepatic failure, abdominal compartment syndrome; acute kidney injury and renal replacement; wounds and pressure injuries. — 21% of the exam. Study guide for Endocrine, Hematology/Immunology, GI, Renal/GU, Integumentary.

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Primary references

  1. CCRN Exam Handbook — Direct Care (July 2026) — AACN Certification Corporation · primary · retrieved 2026-09-22, verified 2026-09-22
Last reviewed: 2026-10-07Reviewed by: Marcus Vance, MSN, RN, CCRN-CSC, Critical care nursing curriculum & clinical item reviewHow we verify facts