What Blood Tests Should I Get for Muscle Weakness?

The key blood tests for muscle weakness are a comprehensive metabolic panel, TSH, vitamin D, magnesium, and a CBC. Electrolyte imbalances (low potassium, calcium) and thyroid dysfunction are leading treatable causes. Vitamin D and magnesium deficiencies also commonly contribute to muscle weakness.

Possible Causes

HypothyroidismVitamin D DeficiencyAdrenal FatigueKidney Disease

Recommended Tests

CMP

$10

Measures 14 substances including glucose, electrolytes, kidney and liver function markers.

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TSH

$8

Measures thyroid-stimulating hormone to evaluate thyroid function. TSH is the most sensitive marker for detecting thyroi...

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Vitamin D

$22

Measures vitamin D status. Deficiency is common and linked to bone health, immune function, and mood.

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RBC Magnesium

$15

Measures magnesium inside red blood cells. More accurate than serum magnesium for assessing true status.

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CBC w/ Diff

$5

Comprehensive blood cell analysis including red cells, white cells, platelets, and white cell differential.

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Total Cortisol

$13

Measures total cortisol levels to assess adrenal function and stress response.

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When to See a Doctor

If your muscle weakness is severe, rapidly worsening, or accompanied by alarming symptoms (chest pain, shortness of breath, high fever), seek immediate medical attention. Blood tests are a valuable first step, but they don't replace evaluation by a healthcare professional.

Frequently Asked Questions

Related Symptoms

FatigueJoint PainLow EnergyCold Intolerance

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Content reviewed for accuracy by the JustLabs editorial team.