From the Guidelines
To evaluate limb movements during sleep, I recommend ordering a comprehensive blood panel including complete blood count (CBC), ferritin, iron studies, vitamin B12, folate, and thyroid function tests, as iron deficiency is strongly associated with periodic limb movement disorder (PLMD) and restless legs syndrome (RLS) 1. When evaluating limb movements during sleep, it is essential to consider the potential underlying causes of PLMD or RLS.
- Low ferritin and iron levels are particularly important to check, as iron deficiency is strongly associated with these conditions, even when hemoglobin levels appear normal 1.
- Vitamin B12 and folate deficiencies can cause neurological symptoms that may manifest as limb movements during sleep.
- Thyroid dysfunction can also contribute to sleep disturbances and movement disorders. Additionally, consider checking kidney function with creatinine and BUN tests, as renal insufficiency can exacerbate RLS symptoms 1.
- If the patient is taking medications, particularly antidepressants or antipsychotics, these should be reviewed as they can sometimes induce or worsen limb movements during sleep. These blood tests provide objective data to guide treatment decisions, which might include iron supplementation, vitamin replacement, or medication adjustments depending on the findings 1. The most recent and highest quality study suggests that iron supplementation is likely to improve restlessness and restless legs syndrome severity in comparison to placebo, even in patients without low blood levels of iron 1.
From the Research
Limb Movements in Sleep and Blood Work
- Limb movements in sleep, such as those experienced in restless legs syndrome (RLS) and periodic limb movement disorder (PLMD), can be evaluated through blood work to check for iron deficiency or other underlying conditions 2, 3, 4, 5.
- Iron deficiency is a common underlying condition in RLS and PLMD, and iron supplementation can be an effective treatment 3, 4, 5.
- Blood tests can measure serum ferritin levels, which can indicate iron deficiency, and transferrin saturation, which can also indicate iron deficiency 5.
- Other blood tests may be ordered to rule out other underlying conditions, such as kidney disease or diabetes, which can contribute to RLS and PLMD 2, 5.
Treatment and Blood Work
- Treatment for RLS and PLMD may involve iron supplementation, dopaminergic medications, or other therapies 2, 3, 4, 5.
- Blood work may be ordered to monitor the effectiveness of treatment and to check for any potential side effects 3, 4, 5.
- For example, iron supplementation can increase serum ferritin levels and reduce symptoms of RLS and PLMD 3, 4.
- Dopaminergic medications can also be effective in reducing symptoms of RLS and PLMD, and blood work may be ordered to monitor their effectiveness and potential side effects 2, 5.
Relationship Between Limb Movements in Sleep and Blood Pressure
- Treatment of periodic limb movements in sleep (PLMS) has been shown to decrease systolic blood pressure in patients with and without sleep apnea 6.
- The exact mechanism of this relationship is not fully understood, but it is thought that improving sleep quality through treatment of PLMS may have a positive effect on blood pressure 6.
- Further research is needed to fully understand the relationship between limb movements in sleep and blood pressure, and to determine the potential benefits of treatment on cardiovascular health 6.