A patient is scheduled for an intravenous pyelogram (IVP). After being NPO for 8 hours, the patient reports thirst. Lab results show: serum osmolarity 300 mOsm/L, serum sodium 155 mEq/L, and urine specific gravity normal. What is the most likely nursing interpretation?

1. A

   Fluid restriction; thirst is expected due to NPO

2. B

   ADH hormone is increased

3. C

   Kidney is not working properly

4. D

   Patient has diabetes insipidus

Appeared in: NORCET 9 Prelims-2025

Explanation

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• The patient exhibits classic signs of dehydration: high serum sodium (155 mEq/L) and high serum osmolarity (300 mOsm/L).
• In a normal physiological response to dehydration, Antidiuretic Hormone (ADH) would cause the kidneys to conserve water, leading to highly concentrated urine with a high specific gravity.
• The finding of a 'normal' urine specific gravity is inappropriate in this context. It indicates that the kidneys are not concentrating urine despite the body's dehydrated state.
• This specific triad of hypernatremia, hyperosmolarity, and an inability to concentrate urine is the hallmark of Diabetes Insipidus (DI).

Why Other Options Were Wrong

• Option A: While thirst is expected with NPO status, a normal physiological response would also include the kidneys concentrating urine to conserve water, resulting in a high urine specific gravity. The 'normal' specific gravity here is a pathological sign.
• Option B: If ADH were increased and functioning correctly, it would cause the kidneys to reabsorb water, leading to a high urine specific gravity. The patient's normal specific gravity indicates that ADH is either deficient (Central DI) or ineffective at the kidney level (Nephrogenic DI).
• Option C: This statement is too general. While the kidneys are not functioning correctly in their role of water conservation, 'Diabetes Insipidus' is the specific diagnosis that precisely describes the hormonal/renal defect presented by the lab values.

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Clinical Relevance

• Nursing practice connection: Knowing Interpretation of lab values for diagnosing Diabetes Insipidus helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Nurses must recognize the triad of symptoms for DI (polyuria, polydipsia, dehydration) and lab findings (hypernatremia, low urine specific gravity) to initiate prompt interventions and prevent life-threatening dehydration and electrolyte imbalances.
• Accurate monitoring of intake, output, daily weight, and neurological status is critical in managing patients with DI, as rapid fluid shifts can lead to cerebral edema or hypovolemic shock.
• What if? If the patient's labs showed low serum sodium (e.g., 125 mEq/L), low serum osmolarity, and high urine specific gravity, the diagnosis would shift to Syndrome of Inappropriate Antidiuretic Hormone (SIADH), and the treatment would be fluid restriction, the opposite of DI management.

How to Approach the Question

• First, identify the key clinical information: the patient is NPO and thirsty, suggesting dehydration.
• Next, analyze the lab values against their normal ranges. Recognize that serum sodium (155 mEq/L) and osmolarity (300 mOsm/L) are high, confirming systemic dehydration.
• Critically evaluate the urine specific gravity. Understand that while a 'normal' value might seem reassuring, in the context of dehydration, it is an abnormal finding. The expected finding would be a high specific gravity.
• Correlate the triad of findings: high serum sodium, high serum osmolarity, and inappropriately normal/low urine specific gravity. This specific pattern points directly to a failure in the ADH system.
• Evaluate the options based on this correlation. Eliminate options that describe a normal response or are too general, and select the option that names the specific condition matching the evidence: Diabetes Insipidus.

Concept Tested & Keywords

• Concept Tested: Interpretation of lab values for diagnosing Diabetes Insipidus
• Stem keywords: intravenous pyelogram (IVP), NPO, thirst, serum osmolarity, serum sodium, urine specific gravity
• Lead-in keywords: most likely nursing interpretation
• Clinical cues: Serum sodium 155 mEq/L indicates hypernatremia.
• Clinical cues: Serum osmolarity 300 mOsm/L indicates hyperosmolarity.

Question ID

Q5J1Md13LGo83ia9p2vqX2

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Reference Book

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 4 p. 11-13

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 141-143

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 524-526