# Situation: A mental health day program at a government hospital serves adults with mood disorders. During the weekly clinic, the nurse reviews each client's treatment plan. A 28-year-old woman taking valproate for bipolar I disorder has had drowsiness, confusion, and vomiting for 2 days. Her valproate level is 85 mcg/mL (therapeutic range for mania 50–125 mcg/mL), and her liver function tests and serum lipase are normal. Which test should the nurse ask the prescriber to order?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=630214  
> language: ko  
> subject: Nursing Practice V — Care of Clients with Maladaptive Patterns of Behavior; Care of Clients with Life-Threatening Conditions, Acute Multi-Organ Problems, High Acuity and Emergency Situations

## 문제

Situation: A mental health day program at a government hospital serves adults with mood disorders. During the weekly clinic, the nurse reviews each client's treatment plan.

A 28-year-old woman taking valproate for bipolar I disorder has had drowsiness, confusion, and vomiting for 2 days. Her valproate level is 85 mcg/mL (therapeutic range for mania 50–125 mcg/mL), and her liver function tests and serum lipase are normal. Which test should the nurse ask the prescriber to order?

## 보기

1. Platelet count
2. Thyroid-stimulating hormone level
3. Serum sodium level
4. Serum ammonia level **✔ 정답**

**정답: 4**

## 해설

Valproate can raise blood ammonia and cause lethargy, vomiting, and confusion even with a therapeutic drug level and normal liver tests. Normal lipase makes pancreatitis less likely. An ammonia level is checked when a client on valproate becomes lethargic or confused.

## 심화 해설

Clinical context

A 28-year-old woman with bipolar I disorder is taking valproate. She now has drowsiness, confusion, and vomiting for 2 days. Her valproate level is 85 mcg/mL, which is inside the therapeutic range for mania (50–125 mcg/mL). Liver function tests and serum lipase are normal. The key point is that a therapeutic drug level and normal liver tests do not rule out a serious valproate-related neurotoxicity.

Why the answer is serum ammonia

Valproate can raise blood ammonia even when the valproate level is therapeutic and liver enzymes are normal [1][2]. The clinical picture of drowsiness, confusion, and vomiting matches valproate-induced hyperammonemic encephalopathy (VHE). In VHE, the patient develops a decreasing level of consciousness, cognitive slowing, lethargy, vomiting, and drowsiness [1]. The main biochemical driver is hyperammonemia, not a high valproate level or hepatocellular injury [1][2].

A normal valproate level and normal liver function tests do not exclude hyperammonemic encephalopathy. Valproate-associated hyperammonemia can occur in people with normal liver function, despite normal doses and serum levels of VPA [2]. Therefore, when a patient on valproate becomes lethargic or confused, the prescriber should order a serum ammonia level.

Why the other options are less appropriate

| Option | Why it is not the priority |
| --- | --- |
| 1. Platelet count | Valproate can cause thrombocytopenia, but drowsiness, confusion, and vomiting are not typical presenting features of low platelets. Bleeding or bruising would be more relevant. |
| 2. TSH level | Valproate may affect thyroid function over time, but acute drowsiness, confusion, and vomiting do not point to hypothyroidism or hyperthyroidism as the immediate cause. |
| 3. Serum sodium level | Hyponatremia can cause confusion and vomiting, but valproate is not a common cause of acute hyponatremia. The symptom cluster and drug exposure make hyperammonemia far more likely. |
| 4. Serum ammonia level | Directly evaluates the suspected mechanism of valproate-induced encephalopathy. This is the correct test when a patient on valproate becomes lethargic or confused. |

Pathophysiology and clinical reasoning

Valproate increases blood ammonia through several mechanisms. It can reduce hepatic urea cycle activity and increase renal ammonia production. The resulting hyperammonemia crosses the blood–brain barrier and causes cerebral edema and neurotoxicity. The clinical syndrome includes vomiting, drowsiness, lethargy, cognitive slowing, and focal neurological deficits [1]. Because the valproate level is therapeutic and liver enzymes are normal, the patient does not have simple valproate toxicity or valproate-induced hepatitis. Normal serum lipase makes pancreatitis less likely, which is important because valproate can also cause pancreatitis.

Watch out! Hyperammonemic encephalopathy can occur with a normal valproate level and normal liver tests. Do not wait for an elevated valproate level or abnormal LFTs before checking ammonia.

Key point! In a patient on valproate with new drowsiness, confusion, and vomiting, the first metabolic test to request is a serum ammonia level, regardless of the valproate concentration.

Clinical application for nursing practice

The nurse should recognize that valproate-related neurotoxicity is a clinical diagnosis supported by an elevated ammonia level. The nurse should ask the prescriber to order a serum ammonia level and should monitor the patient’s level of consciousness, orientation, and vital signs. If ammonia is elevated, the prescriber may reduce or discontinue valproate and consider treatments such as lactulose or L-carnitine [1]. Early recognition prevents progression to coma.

The priority nursing action is to identify the likely cause of altered mental status in a patient taking valproate by requesting a serum ammonia level. This test directly evaluates the suspected mechanism of valproate-induced hyperammonemic encephalopathy [1][2].References (research sources)

- [1]Valproate-induced hyperammonemic encephalopathy.Research articleSegura-Bruna N, Rodriguez-Campello A, Puente V, Roquer J (2006) · DOI: 10.1111/j.1600-0404.2006.00655.x

- [2]Valproate-associated hyperammonemic encephalopathy.Research articleWadzinski J, Franks R, Roane D, Bayard M (2007) · DOI: 10.3122/jabfm.2007.05.070062

## 임상 시나리오

Valproate Neurotoxicity WorkupThink ammonia even when level and LFTs are normal
In a patient on valproate with new drowsiness, confusion, and vomiting, order a serum ammonia level. Hyperammonemic encephalopathy can occur even when the valproate level is therapeutic and liver function tests are normal.

A valproate level of 85 mcg/mL is within the typical mania range of 50-125 mcg/mL, but this does not exclude neurotoxicity. Normal lipase makes pancreatitis less likely.

CautionDo not wait for elevated liver enzymes or a supratherapeutic drug level before checking ammonia. Early recognition of valproate-induced hyperammonemic encephalopathy can prevent progression to coma.

## 핵심 개념

- **valproate-induced hyperammonemic encephalopathy** — Neurotoxicity from elevated blood ammonia caused by valproate, presenting with lethargy, confusion, vomiting, and decreased consciousness even with therapeutic drug levels and normal liver enzymes.
- **therapeutic drug level** — A serum drug concentration within the expected effective range; for valproate in mania, commonly cited as 50-125 mcg/mL.
- **serum ammonia** — A blood test used to detect hyperammonemia, which can explain encephalopathic symptoms in patients taking valproate.
- **bipolar I disorder** — A mood disorder characterized by manic episodes, often managed with mood stabilizers such as valproate.
- **hepatotoxicity** — Liver injury that can occur with valproate, but normal liver function tests do not exclude hyperammonemic encephalopathy.

## 같은 주제 문제

- [Situation: A 29-year-old man is admitted to the psychiatric unit of a general hospital aft…](https://mymerci.kr/pages/nclex_q.php?qn_id=629986)
- [Situation: A 29-year-old man is admitted to the psychiatric unit of a general hospital aft…](https://mymerci.kr/pages/nclex_q.php?qn_id=629987)
- [Situation: A 29-year-old man is admitted to the psychiatric unit of a general hospital aft…](https://mymerci.kr/pages/nclex_q.php?qn_id=629988)
- [Situation: A 29-year-old man is admitted to the psychiatric unit of a general hospital aft…](https://mymerci.kr/pages/nclex_q.php?qn_id=629989)
- [Situation: A 52-year-old man is seen at the outpatient mental health clinic of a provincia…](https://mymerci.kr/pages/nclex_q.php?qn_id=629990)
- [Situation: A 52-year-old man is seen at the outpatient mental health clinic of a provincia…](https://mymerci.kr/pages/nclex_q.php?qn_id=629991)
- [Situation: A 52-year-old man is seen at the outpatient mental health clinic of a provincia…](https://mymerci.kr/pages/nclex_q.php?qn_id=629992)
- [Situation: A 40-year-old woman is admitted to the psychiatric ward with major depressive d…](https://mymerci.kr/pages/nclex_q.php?qn_id=629993)

---

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

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