Medical Surgical SIADH vs DI #5

Question

Which supports the diagnosis of diabetes insipidus? Select all that apply.

Answers

  1. Hyperosmolality
    • Rationale:

      This answer is correct because the osmolarity of the blood is high (hyperosmolality) in DI. This is because fluids are released excessively through the kidneys due to the lack of ADH.

  2. Serum sodium 143 mEq/L
    • Rationale:

      This answer is not correct because serum sodium would be elevated, not normal (135-145 mEq/L). The serum sodium level is elevated due to the decrease of fluid in the bloodstream.

  3. Urine specific gravity of 1.032
    • Rationale:

      This answer is not correct because in DI, the urine specific gravity is low or <1.005. The level in the answer is within normal range.

  4. Excessive thirst
    • Rationale:

      This answer is correct because excessive thirst with excessive, frequent urination are major symptoms of DI. This is due to the lack of ADH in the body.

  5. Blood pressure 80/62 mm Hg
    • Rationale:

      This answer is correct because hypotension is a consequence of the decreased fluid in the blood. The client is at risk for hypovolemic shock. All of this is due to the lack of ADH in the body.

Overview

Diabetes insipidus signs and symptoms include increased blood osmolality (hyperosmolality), the serum sodium level is elevated (>145 mEq/L), urine specific gravity is low, hypotension, excessive thirst, and frequent urination.

Explanation

Learning Outcomes

Diabetes insipidus (DI) is a condition that occurs related to lack of antidiuretic hormone (ADH). The lack of ADH causes a disorder of salt and water imbalance. This is a disorder involving ADH, a hormone produced in the pituitary, it is not diabetes mellitus, a disorder involving the pancreas and insulin. The major symptoms of DI are extreme thirst and frequent urination. The extreme urination can lead to dehydration, hypovolemia, and hypotension. The osmolarity of the blood is high (hyperosmolality), the serum sodium level is elevated (>145 mEq/L) and urine specific gravity is low in DI. Treatment of DI requires long-term vasopressin therapy and the client should not decrease the dose. Vasopressin is an antidiuretic hormone used to enhance reabsorption of water in the kidneys when diabetes insipidus is present.

Test Taking Tip

Understanding normal labs is helpful to determine the correct answer.

Video Rationale