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11 Signs & Symptoms of Calcium Deficiency (Hypocalcemia)

Written by Biljana Novkovic, PhD | Last updated:
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Biljana Novkovic, PhD | Last updated:

Calcium deficiency is relatively common but can be hard to pinpoint. How do you know if you lack calcium? Calcium deficiency can cause diverse health issues: tingling in the hands and feet, muscle aches, irregular heartbeat, fatigue, and even memory loss. Learn how to spot the signs and symptoms of low blood calcium levels.

What is Calcium Deficiency (Hypocalcemia)?

Hypocalcemia is excessively low levels of calcium in the blood. Depending on the severity, symptoms can range from mild or unnoticeable to serious and life-threatening. Calcium deficiency can be both acute and chronic [1].

Calcium is the most abundant mineral in the human body. It is vital for the bones, heart, muscles, and nervous system. Every cell in your body needs calcium! But only around 1% of your calcium is found in the blood, while the remaining 99% is stored in the bones and teeth [2].

Keep in mind that blood calcium levels usually decrease due to non-dietary causes, and rarely due to dietary calcium deficiency. Read more about what causes hypocalcemia here.

Calcium Blood Test

A calcium test measures your calcium levels in the blood. Most commonly, the test estimates your total serum calcium, which includes [3, 4]:

  • Calcium bound to proteins, mainly albumin (about 40 – 45%)
  • Calcium complexed with phosphate and citrate (about 10%)
  • Ionized calcium, also known as free or active calcium (about 45 – 50%)

You don’t need to prepare for this test or fast beforehand. A healthcare professional will simply collect a blood sample from your vein that will be analyzed.

Your doctor may also order an ionized (free) calcium test.

Ionized calcium is the body’s active form of calcium. It is assumed to be around 45 – 50% of the total blood calcium, although the exact percentage may vary. Ionized calcium levels are often estimated based on total blood calcium and albumin levels. Testing ionized calcium is far more precise, but it requires special equipment and is expensive [3].

Low Levels

The normal range for calcium levels in adults is around 8.5 to 10.5 mg/dL. These values can vary slightly from lab to lab. Hypocalcemia is defined as total blood calcium under 8.5 mg/dL. If calcium blood levels drop under 7 mg/dL, hypocalcemia is considered severe [5, 6, 7].

Hypocalcemia Signs and Symptoms

Hypocalcemia can be life-threatening if left untreated. If you’re experiencing any of these symptoms, seek medical attention immediately. Your doctor will run tests to uncover the underlying causes.

1) Muscle Cramps & Spasms

The hallmark symptoms of calcium deficiency are muscle cramps and spasms. Calcium helps muscles contract and relax. Muscles lacking calcium can no longer maintain their normal tone. This can lead to aches, cramps, spasms, and muscle weakness [8, 9, 10].

2) Numbness and Tingling

Another key symptom of hypocalcemia is tingling in the extremities, especially in the hands and feet. Severe deficiency can also cause numbness. Every nerve cell in your body needs calcium. When calcium drops too low, nerve cells struggle to register sensations and send off signals [8, 9, 10, 11].

3) Fatigue

Hypocalcemia may cause fatigue. Since muscle fibers and nerves require calcium, its depletion in cells marks the onset of fatigue, leading to exhaustion and weakness [1, 12, 13].

4) Abnormal Heart Rhythm

Irregular heartbeat is a typical symptom of hypocalcemia and can be life-threatening if severe. It frequently causes several abnormalities that can be registered by an electrocardiogram (ECG).

It’s no surprise that calcium deficiency can disrupt the heart, considering that the heart is a muscle. If heart cells don’t get enough calcium, they stop working as they should. This can set off the normal heart rhythm, cause spasms of the heart muscle, and narrow the arteries [14, 15, 16].

5) Seizures

Brain cells need optimal levels of calcium to release neurotransmitters, while muscles need it to contract. Hypocalcemia can over-excite the brain, which can trigger seizures [10].

6) Osteopenia & Osteoporosis

Osteoporosis or brittle bones is considered a calcium deficiency disorder. Osteopenia is a milder form of osteoporosis. When calcium levels in the blood drop, your body has to release more of it from bones to compensate. Over time, calcium deficiency can cause extreme bone weakness, frailty, and dramatically increase the risk of fractures [17].

7) Dry skin

Dry or scaly skin may be a symptom of hypocalcemia. Calcium’s less-known role is to support skin health: it decreases the pH of the skin and protects the skin barrier. This prevents the excessive loss of water from the skin. When calcium blood levels fall too low, the skin can no longer maintain moisture and a healthy pH [18, 19, 1].

8) Confusion and Memory Loss

Confusion, disorientation, and memory loss can all be symptoms of hypocalcemia. Nerve and brain cells depend on calcium. Calcium entering nerve cells stimulates the release of neurotransmitters. Calcium deficiency can significantly impair cognitive function [20, 1, 21, 11].

9) Premenstrual Syndrome (PMS)

Premenstrual syndrome (PMS) is extremely common and the exact causes are diverse. Low levels of vitamin D and calcium can trigger it or contribute to the symptoms, according to a large review of 28 trials. In such cases, vitamin D and calcium can reduce or even eliminate the symptoms of PMS [22].

10) Tooth Decay and Gum Disease

Calcium keeps your teeth strong. Food, drinks, and mouth bacteria can all degrade minerals in the teeth. Adequate calcium levels are necessary to prevent this mineral loss. What’s more, studies suggest that calcium deficiency is one of the culprits of gum disease [23, 24].

11) Rickets

A lack of calcium (or vitamin D) can lead to rickets in children. Calcium deficiency prevents the proper mineralization of bones, which is extremely important for a growing child. Bones become weak and soft, while deformities are also possible. Rickets is uncommon in the developed world [25, 26].


You may or may not experience symptoms if your blood calcium levels are low. Symptoms can be mild or severe, depending on the extent and duration of time you’ve been in hypocalcemia. Muscle cramps, spasms, and fatigue are common. Other typical symptoms include numbness or tingling in the hands and feet, as well as irregular heart rhythm. In the long run, calcium deficiency can weaken your bones and teeth. Your doctor will run a blood test to check your calcium levels and uncover the underlying causes of a potential deficiency.

About the Author

Biljana Novkovic

Biljana received her PhD from Hokkaido University.
Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science and health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.


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