Calcium deficiency is relatively common but can be hard to pinpoint. How do you know if you lack 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].

Recommended Daily Intake

Below are shown the Recommended Dietary Allowances (RDAs) for calcium. You should aim to get enough calcium every day, either from food or supplements. Going below the RDA for a short while is unlikely to cause harm, but it can lead to health problems in the long run [2].

0–6 months*200 mg200 mg
7–12 months*260 mg260 mg
1–3 years700 mg700 mg
4–8 years1,000 mg1,000 mg
9–13 years1,300 mg1,300 mg
14–18 years1,300 mg1,300 mg1,300 mg1,300 mg
19–50 years1,000 mg1,000 mg1,000 mg1,000 mg
51–70 years1,000 mg1,200 mg
71+ years1,200 mg1,200 mg

* Adequate Intake (AI)

Calcium Blood Test

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

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

The calcium blood test is often done as part of a routine metabolic panel. The basic metabolic panel (BMP) checks blood sugar, calcium, and electrolytes, as well as kidney function. The comprehensive metabolic panel (CMP) also includes cholesterol, protein levels, and markers of liver function [5].

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 50% of the total blood calcium, although the exact percentage may vary. Ionized calcium levels are often just 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 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 [6, 7, 8].

Serious calcium deficiency is rare. However, a lower-than-recommended dietary intake is common and can cause a mild, chronic deficiency with negative health consequences [9, 10].

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 of your deficiency.

If you have mild or temporary hypocalcemia, you can improve by getting more calcium and vitamin D. Our post about the benefits of calcium breaks down the pros and cons of supplementation. Also, be sure you know the difference between various calcium formulations and doses.

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 tonicity. This can lead to aches, cramps, spasms, and muscle weakness [11, 12, 13].  

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 [11, 12, 13, 14].  

3) Fatigue

Hypocalcemia may cause fatigue. Since muscle fibers and nerves require calcium, its depletion in cells marks the onset of fatigue. Lacking calcium, the cells’ inner environment can become overwhelmed with phosphate, leading to exhaustion and weakness [1, 15, 16].

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 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 [17, 18, 19].

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. Without enough calcium, the brain loses its ability to quench and slow excessive activity [13].

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 [20].

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 [21, 22, 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 [23, 1, 24, 14].

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 [25].

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 [26, 27].

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 [28, 29].


Did you know that you can analyze your calcium lab test results with Lab Test Analyzer? It gives you natural recommendations and tells you if your values are below or in the range you need for optimal health.  

LabTestAnalyzer is a sister company of SelfHacked. The proceeds from your purchase of this product are reinvested into our research and development, in order to serve you better. Thank you for your support.


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 an irregular heart rhythm. In the long run, calcium deficiency will weaken your bones and teeth. Your doctor will run a blood test to check your calcium levels and uncover the underlying cause of the deficiency.

About the Author

Jimmy Julajak, MSc

MS (Psychology)

Jimmy got his MSc from the University of Copenhagen.

Jimmy is a psychologist and researcher. He is particularly interested in the workings of the brain and strategies for improving brain health. He believes that people shouldn't hand over the responsibility for their health only to their doctors. His aim is to empower each person with easy-to-understand, science-based health knowledge.

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