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Difficulty: Very hardPharmacological Therapies

A client diagnosed with bipolar disorder has been managed on a daily maintenance dose of oral lithium. Three days ago, the healthcare provider prescribed oral hydrochlorothiazide for newly diagnosed hypertension. During the morning assessment, the practical nurse notes the client is experiencing vomiting, profound muscle weakness, and new-onset coarse hand tremors. The client's morning serum sodium level is 128 mEq/L128\text{ mEq/L} (128 mmol/L128\text{ mmol/L}). Which action should the practical nurse take first?

  1. Withhold the morning doses of both lithium and hydrochlorothiazide and immediately notify the registered nurse.Answer
  2. B
    Document the serum sodium level in the electronic health record and proceed with administering the scheduled hydrochlorothiazide.
  3. C
    Contact the pharmacy to request a temporary reduction in the lithium dosage until the client's serum sodium normalizes.
  4. D
    Administer a prescribed as-needed antiemetic for the vomiting and instruct the client to maintain strict bedrest.

Answer

The priority action is to withhold the morning doses of both lithium and hydrochlorothiazide and immediately notify the registered nurse.
The correct answer synthesizes three critical clinical points: the drug-drug interaction between lithium and thiazide diuretics, the interpretation of a critically low sodium level (128 mEq/L128\text{ mEq/L}), and the recognition of advanced lithium toxicity symptoms (coarse tremors, vomiting, profound weakness). Thiazide diuretics cause sodium depletion. Because lithium has a similar chemical structure to sodium, the kidneys compensate for hyponatremia by reabsorbing lithium, rapidly leading to toxicity. The safest and most appropriate action within the practical nursing scope of practice is to withhold both the diuretic and the lithium, and immediately escalate the situation to the registered nurse.

Step-by-Step Solution

1
Analyze the client's medication regimen and recent additions.
The client is taking lithium (a mood stabilizer) and was recently started on hydrochlorothiazide (a thiazide diuretic).
Identifying drug classes helps predict potential adverse interactions.
2
Evaluate the morning laboratory results.
The serum sodium level is 128 mEq/L128\text{ mEq/L}, which indicates severe hyponatremia (normal range is typically 135135 to 145 mEq/L145\text{ mEq/L}).
Thiazide diuretics promote the excretion of sodium and water, directly causing this low sodium level.
3
Correlate the client's physical symptoms with the physiological effects of the medications.
Because lithium is a salt, the kidneys will reabsorb lithium in the presence of low sodium. This leads to lithium accumulation and toxicity, manifesting as vomiting, profound weakness, and coarse hand tremors.
Recognizing the connection between hyponatremia and lithium toxicity is critical for prioritizing care.
4
Determine the safest priority action within the practical nurse's scope of practice.
The nurse must withhold the interacting medications to prevent further harm and urgently report the critical lab values and toxic symptoms to the registered nurse.
LPNs/LVNs must monitor for adverse effects, ensure medication safety, and escalate acute deteriorations to the RN or provider.

Key Concept

Lithium toxicity precipitated by thiazide diuretic-induced hyponatremia
Estimated Time:1m 30s
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Topics

Pharmacological Therapies

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