Symptom → lab tests
Which blood tests should you get for frequent muscle cramps?
Short answer
Most muscle cramps are benign — exertion, dehydration, pregnancy, age — but frequent or night-time cramps justify checking electrolytes and minerals (potassium, sodium, calcium, magnesium), kidney and liver function, thyroid, blood sugar and vitamin D, plus creatine kinase if muscles are also weak or sore. Statins and diuretics are common medication causes. Cramps with dark urine or severe weakness are urgent.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
When should you see a clinician instead of ordering a test?
- Cramps with dark or cola-colored urine, or severe muscle weakness — same-day care (possible rhabdomyolysis)
- Calf pain and swelling in one leg, especially after travel or immobility (possible clot)
- Cramps with progressive weakness, muscle wasting or twitching
- Cramps that started after a new medication — ask the prescriber rather than stopping it
Why these tests for muscle cramps?
A comprehensive metabolic panel covers potassium, sodium, calcium, kidney and liver function — diuretics, kidney disease and liver disease all disturb the balance muscles depend on. Magnesium is a separate test and a frequent low finding in people with cramps.
Hypothyroidism causes cramps and stiffness; TSH screens for it. A1c and fasting glucose matter because diabetes causes nerve-related cramping, and vitamin D deficiency contributes to muscle aches and weakness.
Creatine kinase measures muscle damage. It is raised with statin-related muscle injury, inflammatory muscle disease and after intense exercise, and helps decide whether cramps are a muscle problem or a nerve/electrolyte one.
Which conditions do these tests help evaluate?
- Thyroid Problems — TSH, Free T4/T3 and antibodies to evaluate an under- or over-active thyroid.
- Diabetes & Blood Sugar — A1c, fasting glucose and insulin to screen for prediabetes and diabetes.
Which tests, and what do they cost?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Fitness & Performance PanelSaves $99.93 vs ordering the tests separately | Panel · 8 tests | $119.99 | Yes | 2–5 business days |
| Vitamin & Mineral Deficiency PanelSaves $106.92 vs ordering the tests separately | Panel · 9 tests | $189.99 | No | 3–5 business days |
| General Wellness PanelSaves $6.97 vs ordering the tests separately | Panel · 4 tests | $89.99 | Yes | 1–3 business days |
| Comprehensive Metabolic Panel | Test · 14 biomarkers | $22.99 | Yes | 1–3 business days |
| Magnesium | Test | $19.99 | No | 2–4 business days |
| TSH (Thyroid Stimulating Hormone) | Test | $26.99 | No | 1–3 business days |
| Vitamin D, 25-Hydroxy | Test | $41.99 | No | 1–3 business days |
| Creatine Kinase (CK) | Test | $18.99 | No | 1–3 business days |
| Hemoglobin A1c | Test | $21.99 | No | 2–4 business days |
| Vitamin B12 | Test | $25.99 | No | 2–4 business days |
| Ferritin | Test | $24.99 | No | 1–3 business days |
Common questions
What deficiency causes leg cramps at night?
Low magnesium, low potassium and low vitamin D are the ones a blood test can confirm; iron deficiency is linked more to restless legs than true cramps. Many night cramps have no deficiency and are related to age, nerve compression or medications.
Can statins cause muscle cramps?
Yes — muscle aches, cramps and weakness are the most common statin side effect. A creatine kinase level tells whether there is actual muscle injury; the decision about the statin belongs with the prescriber.
Should I test magnesium if my metabolic panel is normal?
Yes if cramps persist. Magnesium is not on a standard metabolic panel and is the mineral most often low in cramp-prone people, particularly on diuretics or acid-reducing medication.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.