Calcium Deficiency and Low Blood Calcium: Causes, Symptoms and Testing
Not eating enough calcium versus low blood calcium (hypocalcemia): causes and symptoms the sources list, which tests are used, and why a clinician leads treatment.
Content last updated . This page has not been medically reviewed.
Urgent first
Seizures or breathing problems in someone with low calcium or hypoparathyroidism are an emergency. In the US, call 911 or the local emergency number right away. [1] Muscle spasms that affect the throat can cause breathing difficulty. [1] Other symptoms listed below, such as tingling, cramps or an irregular heartbeat, are reasons to speak to a clinician.Two different problems
"Calcium deficiency" is used for two things, and they are not the same:- Not getting enough calcium in food over a long time. The NHS says a lack of calcium could lead to rickets in children and osteomalacia or osteoporosis in later life. [2]
- Low calcium in the blood (hypocalcemia). This is a medical finding, not a diet label. MedlinePlus says a result lower than normal may reflect low blood protein, an underactive parathyroid gland, too little calcium in the diet, too little vitamin D or magnesium, pancreatitis or kidney disease. [3]
About 1% of the body's calcium is in the blood, and parathyroid hormone works to bring low blood calcium back to normal. [3][4] A low blood result is therefore not just a sign of an empty plate, and symptoms alone cannot tell you which problem you have.
Symptoms the sources list
Many people with low or high calcium have no symptoms. [3] When they occur, MedlinePlus lists muscle cramps, spasms or stiffness; tingling in the lips, tongue, fingers and feet; irregular heartbeat; seizures if levels are extremely low; and, after a long period of low levels, dry skin, coarse hair and nails that break easily. [3] In long-term bone softening, symptoms include fractures without significant injury, muscle weakness and widespread bone pain, especially in the hips. [7] These symptoms have many other causes, so do not diagnose yourself.What the tests can and cannot show
| Test | What it measures | What it cannot show |
|---|---|---|
| Total calcium | All calcium in the blood; often part of a basic or comprehensive metabolic panel. [3] | Calcium in your bones; a bone density scan measures that. [3] |
| Albumin and protein | About half of blood calcium is attached to proteins, mainly albumin, and a low albumin level can lower the total. [8] | Whether the "free" calcium is normal without a further test. |
| Ionized calcium | Free calcium not attached to proteins; usually ordered when total calcium is not normal. [3] | Cause of the abnormal result. |
| Parathyroid hormone (PTH) | Helps find whether parathyroid disorders are causing abnormal calcium; read together with calcium. [4] | Dietary intake on its own. |
| Magnesium, vitamin D, kidney tests | Checked because low magnesium, low vitamin D and kidney disease can all lower calcium. [3] | A single test cannot name the cause. |
One lab list gives a normal total calcium range of 8.8 to 10.3 mg/dL (2.20 to 2.58 mmol/L) but says ranges vary slightly among labs. [8] Your own report's range is the one to use. Diet and certain medicines can affect calcium levels, and an abnormal result does not always mean a condition needing treatment. [3] You may be asked to pause some supplements, such as vitamin D, before a test; do not stop any medicine unless your provider says so. [3] See Calcium tests. At-home or hair "mineral panels" are not described in the sources we read as diagnostic; see Hair mineral analysis.
Treatment is led by a clinician
- For hypoparathyroidism, MedlinePlus describes treatment with calcium carbonate and vitamin D supplements, often for life, with regular blood tests to check the dose is correct. [1]
- Too much treatment with calcium and vitamin D can cause high blood calcium or high urine calcium and may affect the kidneys. [1]
- For rickets and osteomalacia, GPs check vitamin D and calcium levels and treatment depends on the cause. [9]
- MedlinePlus advises talking to a provider before supplementing; a blood test may come first. [5]
Frequently asked questions
What are the symptoms of low calcium?
MedlinePlus lists cramps, spasms, tingling in the lips and fingers, irregular heartbeat and, if extremely low, seizures. Many people have none. [3]
Does a normal blood calcium mean I eat enough calcium?
Not necessarily. A blood test measures the calcium in blood, not in bone. [3] MedlinePlus says a provider may order one to check whether you are getting enough. [5]
What causes low blood calcium?
Causes the sources list include low albumin, an underactive parathyroid gland, too little dietary calcium, low vitamin D or magnesium, pancreatitis and kidney disease. [3]
Can I fix low calcium with supplements on my own?
No. Treatment depends on the cause and is guided by blood tests. [1] Too much calcium and vitamin D can raise blood calcium. [1]
When is low calcium an emergency?
Seizures or breathing problems are an emergency; call 911 in the US. [1]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Who is at risk
- People who eat little calcium: MedlinePlus lists children and teens aged 4 to 18, adults 50 and older living in poverty, postmenopausal women and people who do not eat dairy. [5]
- People with lactose intolerance often have lower intake. [6]
- People with conditions that affect calcium: MedlinePlus names kidney disease, thyroid or parathyroid disease, malnutrition, problems absorbing calcium and certain cancers. [3]
- After neck or thyroid surgery, the most common cause of hypoparathyroidism is injury to the parathyroid glands. [1] See also Minerals after bariatric surgery and Vitamin D deficiency and testing.
Safety notes
- Medicine interactions: Medication interactions and Spacing supplements and medicines.
- Pregnancy, breastfeeding and children: Pregnancy and breastfeeding.
- Too much calcium is also a problem: Too much calcium.
Overview: Calcium.
References
- MedlinePlus Medical Encyclopedia, Hypoparathyroidism. Read 2026-10-22.
- NHS, Calcium (page last reviewed 3 August 2020). Read 2026-10-22.
- MedlinePlus, Calcium Blood Test. Read 2026-10-22.
- MedlinePlus, Parathyroid Hormone (PTH) Test. Read 2026-10-22.
- MedlinePlus, Calcium. Read 2026-10-22.
- MedlinePlus Medical Encyclopedia, Calcium in diet (review date 1/21/2025). Read 2026-10-22.
- MedlinePlus Medical Encyclopedia, Osteomalacia. Read 2026-10-22.
- MedlinePlus Medical Encyclopedia, Calcium blood test. Read 2026-10-22.
- NHS, Rickets and osteomalacia. Read 2026-10-22.