Magnesium · low result
Low magnesium (magnesium deficiency): symptoms, causes and what to check next
Short answer
Low magnesium (hypomagnesemia) — below about 1.7 mg/dL — is common, under-recognized and usually caused by something that wastes magnesium rather than by diet alone: proton-pump inhibitors, diuretics, alcohol, uncontrolled diabetes and chronic diarrhea lead the list. Cramps, twitching, palpitations and fatigue are the typical complaints, and because a low magnesium drags potassium and calcium down with it, those two are checked at the same time.
Medically reviewed by Youmna DiStefano, MD · Last reviewed November 2026
When does this result need same-day care?
- Palpitations with an irregular or racing pulse, fainting, or a seizure with a low magnesium — emergency care; intravenous replacement and cardiac monitoring
- Spasms of the hands and feet, or a magnesium below about 1.0 mg/dL — same-day care
What is the normal range for Magnesium?
- age 18+: 1.70 – 2.20 mg/dL
Common in alcohol use, diuretic use, GI losses, or poor diet. Can cause muscle cramps and arrhythmias.
Full reference table, citations and testing options: Magnesium biomarker page.
What are the common causes of low Magnesium?
- Proton-pump inhibitors (omeprazole, pantoprazole and relatives) taken for more than a year — the most common medication cause; it reverses within weeks of stopping
- Diuretics — loop (furosemide) and thiazide — and other magnesium-wasting drugs: aminoglycosides, amphotericin, cisplatin, calcineurin inhibitors, some EGFR-inhibitor cancer drugs
- Alcohol use disorder — poor intake, urinary loss and often diarrhea together; magnesium is low in most people admitted with heavy alcohol use
- Gastrointestinal loss — chronic diarrhea, Crohn's and ulcerative colitis, celiac disease, short bowel, bariatric surgery, laxative use
- Poorly controlled diabetes — glucose in the urine pulls magnesium out with it; low magnesium in turn worsens insulin resistance
- Low intake over weeks — refeeding after starvation, parenteral nutrition without enough magnesium, very restrictive diets
- Kidney tubular disorders — Gitelman and Bartter syndromes, post-obstructive diuresis, the recovery phase of acute kidney injury
- Hungry bone syndrome after parathyroid surgery, acute pancreatitis, high calcium from any cause, and pregnancy or lactation with marginal intake
What symptoms go with low Magnesium?
- Muscle cramps, twitches and tremor, particularly in the calves and around the eyes
- Fatigue, weakness, poor sleep and low mood — nonspecific, which is why the level is often found incidentally
- Palpitations or a sense of skipped beats; an irregular rhythm when the level is very low
- Numbness and tingling, and at severe levels spasms of the hands and feet (tetany) or a seizure
- Nausea and loss of appetite early on
What do clinicians usually check next?
- Potassium and calcium on the same sample — both fall with magnesium and neither corrects until magnesium is replaced
- A medication review for PPIs and diuretics, and an honest alcohol history; the fix is usually there
- Kidney function (creatinine, eGFR) and, if the cause is not obvious, a 24-hour urine magnesium or spot fractional excretion to separate kidney wasting from gut loss or poor intake
- Glucose or HbA1c when diabetes is possible, and an ECG if there are palpitations, since a low magnesium prolongs the QT interval
- Parathyroid hormone and vitamin D when calcium is also low — magnesium deficiency suppresses PTH and blocks vitamin D activation
- Repeat two to four weeks after the cause is addressed; serum levels lag the body's stores, so a normal repeat does not always mean the deficit is gone
Follow-up tests available at TestWell: Calcium Test ($16.99), PTH Test (Parathyroid Hormone) ($59.99), Glucose Test ($14.99).
How do you recheck Magnesium?
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 Panel | Panel · 8 tests | $119.99 | Yes | 2–5 business days |
| Sleep Health Panel | Panel · 8 tests | $129.99 | Yes | 3–5 business days |
| Vitamin & Mineral Deficiency Panel (9 Nutrients) | Panel · 9 tests | $189.99 | No | 3–5 business days |
| Magnesium Test | Test | $18.99 | No | 2–4 business days |
Common questions
What are the symptoms of magnesium deficiency?
Muscle cramps and twitches, tremor, fatigue, poor sleep, palpitations and, when severe, numbness, tingling, tetany or seizures. Many people have no symptoms at all and the level is found on a panel ordered for another reason.
What is considered a low magnesium level?
Below the laboratory's lower limit, usually about 1.7 mg/dL (0.70 mmol/L). 1.2 to 1.7 is mild to moderate and is typically treated by mouth; below about 1.0–1.2, or any level with arrhythmia, tetany or seizures, is severe.
Can my magnesium be low even if the blood test is normal?
Yes. Serum magnesium is about 1% of the body's total, and the blood level is defended at the expense of bone and muscle stores. A low result is meaningful; a normal one does not exclude a deficit in someone with the symptoms and a cause such as long-term PPI use.
What causes low magnesium?
Most often a medication (PPIs, diuretics), alcohol, chronic diarrhea or bowel disease, and poorly controlled diabetes; less often kidney tubular disorders or simple low intake over weeks. Diet alone rarely produces a low serum level in someone with normal kidneys and gut.
Which foods are high in magnesium?
Pumpkin seeds, almonds and cashews, spinach and other leafy greens, black beans, whole grains, dark chocolate and avocado. Food helps maintain stores but will not correct a deficiency driven by a drug or ongoing loss until the cause is dealt with.
Does low magnesium cause low potassium?
Frequently. Magnesium is needed to keep potassium inside cells and to stop the kidneys wasting it, so a low potassium that will not correct until magnesium is replaced is a classic clue. Calcium behaves the same way through parathyroid hormone.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.