# Situation: A 27-year-old man has passed about 6 liters of urine a day for 2 months and is always thirsty, preferring ice-cold water. His serum sodium is 144 mEq/L (135–145), and his urine specific gravity is 1.002. He takes no medicines. He is admitted for a supervised water deprivation test. The provider explains how each part of the test will be read. Which result would indicate arginine vasopressin resistance (nephrogenic diabetes insipidus)?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=630513  
> language: ko  
> subject: Nursing Practice IV — Care of Clients with Problems in Nutrition and Gastrointestinal, Metabolism and Endocrine, Perception and Coordination

## 문제

Situation: A 27-year-old man has passed about 6 liters of urine a day for 2 months and is always thirsty, preferring ice-cold water. His serum sodium is 144 mEq/L (135–145), and his urine specific gravity is 1.002. He takes no medicines. He is admitted for a supervised water deprivation test.

The provider explains how each part of the test will be read. Which result would indicate arginine vasopressin resistance (nephrogenic diabetes insipidus)?

## 보기

1. Urine osmolality rises above 700 mOsm/kg during water deprivation
2. Urine osmolality rises from 160 to 540 mOsm/kg after desmopressin
3. Serum sodium falls below 135 mEq/L after desmopressin
4. Urine osmolality stays near 160 mOsm/kg after desmopressin **✔ 정답**

**정답: 4**

## 해설

In arginine vasopressin resistance the kidneys cannot respond to vasopressin, so urine stays dilute during water deprivation and still does not concentrate after desmopressin is given. A marked rise after desmopressin points instead to vasopressin deficiency, and concentration during water deprivation itself points to primary polydipsia.

## 심화 해설

Interpreting the response to desmopressin
After water deprivation, desmopressin, a synthetic analog of arginine vasopressin (AVP), the antidiuretic hormone, is given to see whether the kidneys can respond. In arginine vasopressin resistance (formerly nephrogenic diabetes insipidus), the kidneys cannot respond to vasopressin. Urine stays dilute during water deprivation and still does not concentrate after desmopressin. Urine osmolality that stays near 160 mOsm/kg after desmopressin indicates vasopressin resistance.

Comparing the three main causes of polyuria
In arginine vasopressin deficiency (formerly central diabetes insipidus), the pituitary does not release enough vasopressin. The kidneys are normal, so urine concentrates markedly when desmopressin is given, for example from 160 to 540 mOsm/kg. In primary polydipsia, excessive drinking dilutes the urine, but vasopressin release and kidney response are intact, so the urine concentrates during water deprivation itself, for example to above 700 mOsm/kg. In vasopressin resistance, neither deprivation nor desmopressin produces concentrated urine.

| Condition | During water deprivation | After desmopressin |
| --- | --- | --- |
| Primary polydipsia | Urine concentrates | Little further change |
| AVP deficiency (central) | Stays dilute | Marked rise in concentration |
| AVP resistance (nephrogenic) | Stays dilute | Stays dilute |

Why the other results do not indicate resistance
Urine osmolality rising above 700 mOsm/kg during water deprivation shows intact vasopressin release and response, as in primary polydipsia. A marked rise from 160 to 540 mOsm/kg after desmopressin shows that the kidneys respond, which indicates vasopressin deficiency. A fall in serum sodium below 135 mEq/L after desmopressin reflects water retention while the client continues to drink, not kidney resistance. Watch out! Current terminology uses AVP deficiency and AVP resistance; older sources call them central and nephrogenic diabetes insipidus.

Exam takeaway
The key question in the test is where the defect lies: in drinking, in hormone release, or in the kidney's response. Key point! No concentration after desmopressin means the kidney cannot respond to vasopressin: arginine vasopressin resistance.

## 임상 시나리오

Reading the Water Deprivation TestAVP deficiency, resistance, or primary polydipsia
Desmopressin tests the kidney's response to vasopressin after water deprivation.

AVP resistance (nephrogenic): urine stays dilute, near 160 mOsm/kg, even after desmopressin. AVP deficiency (central): urine concentrates markedly after desmopressin.

Primary polydipsia: urine concentrates during water deprivation itself.

CautionAfter desmopressin, restrict drinking to thirst to avoid water retention and hyponatremia.

## 핵심 개념

- **Arginine vasopressin** — Antidiuretic hormone released from the posterior pituitary that makes the kidneys concentrate urine.
- **Arginine vasopressin resistance** — Inability of the kidneys to respond to vasopressin, formerly called nephrogenic diabetes insipidus.
- **Arginine vasopressin deficiency** — Inadequate vasopressin release from the pituitary, formerly called central diabetes insipidus.
- **Desmopressin** — A synthetic vasopressin analog used to test and treat vasopressin deficiency.
- **Primary polydipsia** — Excessive fluid intake that dilutes the urine despite normal vasopressin release and kidney response.

## 같은 주제 문제

- [Situation: A 58-year-old man with alcohol-associated cirrhosis is admitted with tense asci…](https://mymerci.kr/pages/nclex_q.php?qn_id=630291)
- [Situation: A 58-year-old man with alcohol-associated cirrhosis is admitted with tense asci…](https://mymerci.kr/pages/nclex_q.php?qn_id=630292)
- [Situation: A 58-year-old man with alcohol-associated cirrhosis is admitted with tense asci…](https://mymerci.kr/pages/nclex_q.php?qn_id=630293)
- [Situation: A 58-year-old man with alcohol-associated cirrhosis is admitted with tense asci…](https://mymerci.kr/pages/nclex_q.php?qn_id=630294)
- [Situation: A 58-year-old man with alcohol-associated cirrhosis is admitted with tense asci…](https://mymerci.kr/pages/nclex_q.php?qn_id=630295)
- [Situation: A 46-year-old woman with obesity is admitted with acute cholangitis caused by a…](https://mymerci.kr/pages/nclex_q.php?qn_id=630296)
- [Situation: A 46-year-old woman with obesity is admitted with acute cholangitis caused by a…](https://mymerci.kr/pages/nclex_q.php?qn_id=630297)
- [Situation: A 46-year-old woman with obesity is admitted with acute cholangitis caused by a…](https://mymerci.kr/pages/nclex_q.php?qn_id=630298)

---

More free questions: [기출문제](https://mymerci.kr/)

_학습 참고용입니다. 실제 임상은 최신 지침과 소속 기관 프로토콜을 따르세요._