How should I evaluate and manage an 18‑year‑old female with a one‑month history of bilateral lower‑leg pain and restlessness at night causing insomnia, with normal oxygen saturation, pulse, and blood pressure?

Approach to an 18-Year-Old Female with Bilateral Lower Leg Pain, Nighttime Restlessness, and Insomnia

This presentation is highly suggestive of Restless Legs Syndrome (RLS), and you should systematically confirm the diagnosis using the four essential clinical criteria, check iron status, and initiate treatment with gabapentin, pregabalin, or gabapentin enacarbil as first-line therapy.

Diagnostic Approach

Confirm RLS Diagnosis Using Four Essential Criteria

The clinical presentation strongly suggests RLS. You must verify all four diagnostic criteria 1, 2:

1. Urge to move the legs with or without uncomfortable sensations in the lower legs
2. Symptoms begin or worsen during rest (sitting or lying down)
3. Symptoms are relieved by movement (walking, stretching)
4. Symptoms are worse in the evening/night than during the day

This patient's bilateral lower leg pain with nighttime restlessness and insomnia fits this pattern perfectly. RLS affects approximately 10% of the Caucasian population and can occur at any age, including adolescents 3. Research shows that female adolescents with musculoskeletal pain have significantly higher rates of RLS (34.6%) compared to controls (4%) 4.

Essential Laboratory Evaluation

Check iron parameters immediately - this is critical before initiating any treatment 5:

• Serum ferritin (most important)
• Transferrin saturation
• Complete blood count

Iron deficiency is a major contributor to RLS pathophysiology and must be identified and corrected 2. The guidelines emphasize checking "appropriate iron status" before considering iron supplementation.

Rule Out Secondary Causes

At age 18, consider:

• Medications that may worsen RLS (antihistamines, antidepressants, antipsychotics)
• Pregnancy (if applicable)
• Renal disease
• Peripheral neuropathy (though less likely at this age)

Treatment Algorithm

First-Line Pharmacologic Treatment

The 2025 AASM guidelines provide strong recommendations for three medications as first-line therapy 5:

1. Gabapentin enacarbil (strong recommendation, moderate certainty)
2. Gabapentin (strong recommendation, moderate certainty)
3. Pregabalin (strong recommendation, moderate certainty)

These alpha-2-delta ligands are now preferred over dopaminergic agents because they avoid the serious long-term complication of augmentation (paradoxical worsening of symptoms with dopamine agonists).

Iron Supplementation (If Indicated)

If iron parameters are low 5:

• IV ferric carboxymaltose (strong recommendation, moderate certainty) - preferred IV option
• Ferrous sulfate (conditional recommendation, moderate certainty) - oral option
• IV low molecular weight iron dextran or ferumoxytol (conditional recommendations)

Iron supplementation improves RLS symptoms and may reduce the need for other medications 2.

What NOT to Use as Standard Treatment

Avoid dopamine agonists (pramipexole, ropinirole, rotigotine) as standard first-line therapy 5. The 2025 AASM guidelines now suggest against their standard use due to the high risk of augmentation with long-term use. They may only be considered in patients who prioritize short-term symptom relief over long-term adverse effects.

Do not use 5:

• Bupropion (conditional recommendation against)
• Carbamazepine (conditional recommendation against)
• Clonazepam (conditional recommendation against)
• Valproic acid (conditional recommendation against)
• Cabergoline (strong recommendation against)

Managing the Insomnia Component

While treating the underlying RLS will improve sleep, if insomnia persists after RLS treatment:

Cognitive Behavioral Therapy for Insomnia (CBT-I) is the first-line treatment for chronic insomnia 6. This includes:

• Sleep restriction
• Stimulus control
• Cognitive therapy
• Sleep hygiene education

Pharmacologic treatment for insomnia should only be added if CBT-I alone is unsuccessful 6.

Common Pitfalls to Avoid

1. Missing the diagnosis: RLS is underdiagnosed, especially in young patients 7, 3. The nighttime pattern and urge to move are key distinguishing features.

2. Starting dopamine agonists first: This was previous practice but is now discouraged due to augmentation risk. The 2025 guidelines represent a major shift toward alpha-2-delta ligands 5.

3. Ignoring iron status: Always check and correct iron deficiency - it's both therapeutic and may prevent augmentation if other medications are needed 2.

4. Treating only the insomnia: The insomnia is secondary to RLS in this case. Treating the RLS will improve sleep quality 8.

Specific Management Steps for This Patient

1. Confirm diagnosis using the four clinical criteria during history
2. Order labs: ferritin, transferrin saturation, CBC
3. Initiate gabapentin (300-1200 mg at night), gabapentin enacarbil (600 mg), or pregabalin (75-450 mg) 5
4. Add iron supplementation if ferritin is low (specific thresholds per AASM good practice statement)
5. Reassess in 2-4 weeks for symptom improvement and medication tolerance
6. Consider CBT-I referral if insomnia persists despite RLS treatment

The normal vital signs (SpO2 98%, pulse 78 bpm, BP 110/60 mmHg) rule out acute cardiopulmonary issues but don't exclude RLS, which is a neurological disorder with normal physical examination findings 1.