12 Causes of Hypocalcemia (Calcium Deficiency)

Could You Have a Calcium Deficiency?

12 Causes of Hypocalcemia (Calcium Deficiency)

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Calcium is an essential mineral that helps keep your bones and teeth strong. Here's how to tell if you're getting enough of it.

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You have more calcium in your body than any other mineral, and 99% of it is stored in your bones and teeth. This means consuming enough calcium is critical for keeping your bones and teeth strong, especially as you age. Calcium is also important for your nerves, heart, and muscle function.

The current recommended daily allowance (RDA) for women and men is 1,000 mg to 1,300 mg, depending on your age. By staying within these limits, you’ll be on your way toward maintaining healthy bones and teeth and warding off osteoporosis.

But if you don't drink milk or eat dairy products, could you be at risk for a calcium deficiency?



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A true calcium deficiency, or hypocalcemia, usually has nothing to do with diet. Instead, blood levels of calcium become too low as a result of taking certain medications and medical conditions (more on this later).

Dietary calcium deficiency—when you're not taking in enough calcium from food and beverages—is very rare. “I rarely ever see a healthy individual with low calcium,” says Lynn Mack, MD, an endocrinologist at the University of Nebraska Medical Center in Omaha. “Most people can get enough calcium by eating a variety of foods rich in calcium.”

Calcium inadequacy is more common, which is when someone's dietary intake of the mineral is lower than recommended. This can lead to health problems osteoporosis over time.

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Some types of medication can cause hypocalcemia by reducing calcium stores or making it more difficult for the body to absorb calcium. One category of medication is diuretics, which increase how much calcium is passed the body through urine. Certain antibiotics and antiseizure medications can also lower calcium stores.

Proton pump inhibitors (PPIs), which are used to combat stomach acid, don’t cause hypocalcemia, but they could reduce absorption of calcium, says Dr. Mack.

If you are taking a PPI and don’t get enough calcium from food, you may need to take a calcium citrate supplement such as Citracal, which doesn’t need stomach acid to be absorbed, she adds.


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Problems with the parathyroid glands, which are located on the thyroid in the neck, can affect blood calcium levels. These four glands produce parathyroid hormone (PTH), which helps your body maintain appropriate balance of calcium and phosphorus in the blood.

If you’re not producing enough PTH—called hypoparathyroidism, which may be caused by an injury to the gland, a genetic condition, or an endocrine disorder—calcium levels can decline. (If you have too much PTH, on the other hand, then your blood calcium rises.


Kidney dysfunction can also bring down calcium levels; excess calcium is excreted in urine, which affects the kidneys' ability to activate vitamin D.

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There are four groups that are most at risk for calcium inadequacy:

Postmenopausal women: During and after menopause, women produce less estrogen, which in turn decreases calcium absorption and increases bone resorption (the breakdown of old bone).

This can lead to osteoporosis. As you approach menopause, talk to your doctor about whether you should increase the amount of calcium-rich foods in your diet.

The RDA for adult women through age 50 is 1,000 mg, and 1,200 mg after that.

Women with amenorrhea: Amenorrhea is a condition in which menstrual periods stop (or never start) due to low body weight, a hormonal imbalance, stress, or other causes. Women who don't get a period have reduced circulating estrogen levels, which can mess with calcium balance.

Vegans and people who are lactose intolerant: Dairy is the top source of calcium in most diets, so if you avoid those products, you may not be getting enough of the mineral. Loading up on plenty of non-dairy calcium sources, such as collard greens and broccoli, may help offset this.

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There’s an important connection between calcium and vitamin D. “Vitamin D is the key ingredient to allow the gut to absorb calcium,” says Dr. Mack. “So if you are vitamin D deficient, you don’t efficiently absorb calcium.”

Luckily, vitamin D is found in many foods, such as fatty fish (salmon, tuna, mackerel are all great sources), as well as fortified foods, including cereal, milk, and some types of orange juice. Your body also makes vitamin D after you’ve been in the sun, which makes a little exposure every day important (with plenty of SPF, of course).



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If you aren't eating enough calcium-rich foods and have a calcium inadequacy, then you won't experience any symptoms.

Symptoms of hypocalcemia, on the other hand, can vary and depend on what is causing the deficiency, how severe it is, and other individual factors, according to the National Osteoporosis Foundation.

Some people have no symptoms, while others may experience a variety of symptoms, such as muscle cramps or spasms, numbness, tingling sensations, poor appetite, or seizures. In addition, symptoms of related vitamin D deficiency can include achiness or tenderness in the bones, says Dr. Mack.

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A simple bloodtestcan determine if you have low calcium levels.Your doctor might suggest a test if he or she thinks your levels are low due to parathyroid or other health problems.

There are two tests: one measures ionized calcium,but the test can be expensive and readings aren’t always accurate.The other measures total calcium. “It’s what is used by almost everyone to look at the calcium level,” explains Dr. Mack.

If tests show a deficiency, your doctor will try to determine the cause and then decide whether or not you need supplements.

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The good news is that a calcium inadequacy can be corrected simply by ingesting more calcium and making sure you’re also getting enough vitamin D. “It’s better to get calcium through diet,” says Howard A. Selinger, MD, chair of family medicine at the Frank H.

Netter MD School of Medicine at Quinnipiac University in Hamden, Conn. The main sources are dairy products such as milk, low-fat cheese, and yogurt, as well as some fruits and veggies. Many foods have added calcium, including soymilk, bread, and some kinds of bottled water.

And make sure you’re also filling your plate with plenty of vitamin D-rich foods, such as spinach and other deep-colored vegetables. “We say the darker the green, the better for you,” says Dr. Selinger.

If you’re concerned that diet won’t be enough, speak to your doctor about whether or not you need calcium or vitamin D supplements.

When a person has hypocalcemia, a doctor may recommend calcium and vitamin D supplements, and will also work to treat the underlying condition causing it.


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There is such a thing as too much calcium, which is called hypercalcemia. You can consume too much calcium through supplements, but certain health problems can cause your body to develop excessive calcium stores, as well.

Those problems include overactive parathyroid glands, certain cancers, immobility, medications, and hereditary factors. Signs of excessive calcium are nausea, vomiting, confusion, and fatigue.

More serious symptoms can include problems with your kidneys, weakened bones, arrhythmia, or even severe nervous system problems dementia and coma.

Source: https://www.health.com/condition/osteoporosis/calcium-deficiency

Disorders of calcium balance

12 Causes of Hypocalcemia (Calcium Deficiency)

  • Clinical science
  • Physician

The maintenance of calcium homeostasis in the body is complex and influenced by several variables. Calcium is absorbed in the gastrointestinal (GI) tract, integrated into and resorbed from the calcified bone matrix, and renally excreted.

Parathyroid hormone (PTH) regulates all of these processes, which are also dependent on the balance of vitamin D (specifically vitamin D3, or calcitriol), calcitonin, and phosphate in the body. Therefore, disorders of the parathyroid glands as well as the bone, kidney, and GI tract may lead to disruptions in calcium homeostasis.

Hypocalcemia, for example, is most often caused by hypoparathyroidism (e.g., autoimmune, surgical) or vitamin D deficiency (e.g., malabsorption, chronic kidney disease). Hypercalcemia is often the result of either primary hyperparathyroidism or malignancy.

In cases of malignancy, PTH-related protein (PTHrP) produced by tumor cells is often responsible; osteolytic bone metastases (e.g., multiple myeloma) must also be considered.

The concentration of calcium in the serum affects multiple processes in the body, including coagulation, cell signaling, and hormone release. In addition to hormonal control by PTH and calcitriol, calcium homeostasis is influenced by serum protein levels and acid-base status, both of which impact the ratio of protein bound to ionized calcium in the serum.

If serum ionized calcium concentrations are not maintained within a narrow range, signs and symptoms appear in a variety of systems.

Symptoms of hypocalcemia include signs of tetany (typically carpopedal spasm) and a “pins and needles” sensation or other paresthesia, which indicates neuromuscular excitation due to a lessening of the membrane-stabilizing effect normally exerted by calcium.

The presentation of hypercalcemia, in contrast, classically includes stones (nephrolithiasis), bones (bone pain, arthralgias), abdominal groans (abdominal pain, nausea, constipation), and psychiatric overtones (anxiety, depression). Management of calcium imbalance consists primarily of treating the underlying disorder and, if necessary, supplementing or eliminating calcium.

  • Hypercalcemia = total serum calcium concentration > 10.5 mg/dL (> 2.62 mmol/L)

The corrected calcium concentration calculated using serum albumin may not be accurate when major pH changes have taken place in the body (e.g., following surgery). In these cases, it is better to measure ionized calcium directly!

PTH = Phosphate Trashing Hormone

Hypocalcemia is most often due to hypoparathyroidism or vitamin D deficiency (e.g., malabsorption, chronic kidney disease)


Types of hypercalcemia Etiology PathophysiologyPTH-mediated Primary hyperparathyroidismFamilial hypocalciuric hypercalcemiaTertiary hyperparathyroidismNon-PTH-mediated Hypercalcemia of malignancyGranulomatous disorders (e.g., sarcoidosis)Other Intake of medicationsHyperthyroidismLong periods of immobilizationMilk-alkali syndromePaget's disease of the boneAdrenal insufficiency
  • Adenoma (sporadic) or multiple endocrine neoplasia
  • See “Differential diagnosis” below.
  • Most common cause: paraneoplastic production of PTHrP (e.g., squamous cell carcinomas of the lung, head, and neck; renal, bladder, breast, and ovarian cancer; lymphoma and leukemia)
  • Osteolytic metastases (e.g., multiple myeloma, breast cancer, lymphoma and leukemia, renal and prostate cancer)
  • Paraneoplastic production of 1,25-dihydroxyvitamin D (calcitriol): e.g., lymphoma, ovarian dysgerminoma
  • Thyroid hormones have osteoclastic activity.
  • Consumption of calcium carbonate
  • Increased rate of bone remodeling

Primary hyperparathyroidism and hypercalcemia of malignancy account for > 90% of cases of hypercalcemia. Compared with primary hyperparathyroidism, serum calcium is typically higher in hypercalcemia of malignancy (> 13 mg/dL, or > 3.25 mmol/L), and patients therefore exhibit more severe symptoms!

Suspect hypocalcemia in the postoperative thyroidectomy patient with new onset paresthesias and muscle spasms or cramping!

Hypercalcemia (variable presentation, may be asymptomatic)

Calcium and pancreatitis → hypercalcemia can cause pancreatitis. Hypocalcemia in patients with pancreatitis suggests pancreatic necrosis!

The presentation of hypercalcemia includes stones (nephrolithiasis), bones (bone pain, arthralgias), abdominal groans (abdominal pain, nausea, vomiting), and psychiatric overtones (anxiety, depression, fatigue). Note that these are also the findings of vitamin D overdose!

The typical laboratory findings of vitamin D deficiency are: ↓ calcium, ↓/↔︎ phosphate, ↑ PTH!

PTH in hypercalcemia

  • Etiology: autosomal dominant inactivating mutation in the CaSR gene → decreased sensitivity of calcium-sensing receptorskidneysparathyroid glands
  • Clinical features
    • Usually asymptomatic (incidental finding)
    • Neonatal hypocalcemia in children of mothers with FHH
  • Diagnosis
    • Hypercalcemia and inappropriately normal or increased PTH
    • Hypocalciuria
      • ↓ 24-hour urinary calcium excretion (< 200 mg/ day)
  • Therapy: no treatment necessary

The differential diagnoses listed here are not exhaustive.

  • Calcium supplementation

Patients receiving cardiac glycosides (digoxin and digitoxin) should never be given IV calcium, which can provoke ventricular fibrillation!


Loop diuretics Lose calcium → Discontinue them in hypocalcemia!

Thiazide diuretics are calcium sparing → Discontinue them in hypercalcemia!

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  • Video showing Chvostek's sign
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Source: https://www.amboss.com/us/knowledge/Disorders_of_calcium_balance

Hypocalcemia: Updates in diagnosis and management for primary care

12 Causes of Hypocalcemia (Calcium Deficiency)

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12 Causes of Hypocalcemia (Calcium Deficiency)

12 Causes of Hypocalcemia (Calcium Deficiency)

Studies suggest that calcium deficiency is much more common today than most people realize. Hypocalcemia, or low blood calcium, can trigger a wide range of symptoms, including muscle aches, irregular heartbeat, and fatigue. But what causes hypocalcemia in the first place? Read on to find out.


Hypocalcemia is when you have low blood calcium levels (“hypo” = low, “calcemia” = calcium in the blood). This condition can be either transient/acute or chronic.

You may or may not experience symptoms, depending on the severity of your deficiency. Symptoms can range from barely-noticeable and mild to serious and life-threatening complications. Hypocalcemia can even lead to death if left untreated [1].

This is unsurprising given that calcium is the most abundant mineral in the human body. Every cell in your body needs it to function. Calcium supports your bones, heart, muscles, and nervous system. But only around 1% of your total body calcium is found in the blood. The remaining 99% is stored in your bones and teeth [2].


Slightly lower calcium levels will generally not cause any symptoms.

However, more severe deficiency can be accompanied by symptoms such as [1, 3, 4]:

  • Muscle cramps
  • Tingling in the hands and feet
  • Fatigue
  • Confusion
  • Irregular heartbeat
  • Seizures
  • Dry skin
  • Tooth decay
  • Osteoporosis

This post will focus on the causes of calcium deficiency. Read more about the symptoms of calcium deficiency in this post and about the calcium blood test here.

Hypocalcemia Causes

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].

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 [8, 9].

Causes shown below are commonly associated with low calcium levels. Work with your doctor or another health care professional to get an accurate diagnosis. Your doctor will interpret your result, taking into account your medical history, symptoms, and other test results.

If you are suspected of being calcium deficient, your doctor may run more tests to confirm the diagnosis. Possible tests include measurement of magnesium, PTH, phosphate, and vitamin D [7, 1].

1) Vitamin D Deficiency

If you don’t get enough vitamin D (from sun or supplements), you can develop hypocalcemia. This is because vitamin D helps absorb calcium in the gut. Vitamin D deficiency is the most common cause of hypocalcemia in primary care. It is estimated that up to 50% of the population may be deficient in vitamin D, so make sure you are getting enough [10, 11, 12].

2) Hypoparathyroidism (Low PTH)

Calcium blood levels are tightly controlled by parathyroid hormone (PTH). Cells in your parathyroid gland – located in the neck just behind the thyroid – release PTH when they sense a drop in calcium blood levels [13].

PTH raises blood calcium levels by increasing the absorption of calcium from the gut and kidneys. This hormone can also mobilize calcium and phosphate from the bones: that is, it breaks down and frees the mineral content of bones to compensate for low calcium levels. This process is known as bone resorption [13].

PTH also increases the amount of vitamin D that is converted to its active form, calcitriol. Calcitriol increases calcium absorption in the gut [13].

If PTH levels drop too low, so does calcium.

Hypoparathyroidism or underactive parathyroid gland, is when there are low levels of parathyroid hormone. This condition can occur for several reasons, including [14, 10, 15]:

  • Damage to the parathyroid glands (e.g. from surgery, radiation)
  • Autoimmune disorders
  • Genetic disorders

It is also possible to have normal levels of PTH but experience the symptoms of low PTH. This condition is known as pseudohypoparathyroidism and happens when cells stop responding to PTH as they should [10].

3) Not Getting Enough Calcium

This one is perhaps obvious and self-explanatory. But a large study from 2007 showed that most Americans are not getting the calcium they need [16].

People who are lactose intolerant, for example, or have eating disorders are at a higher risk of being calcium deficient [17]

Take a look at the recommended daily intake (RDA) of calcium below, and make sure you’re getting enough. If you can’t get enough from your diet, discuss calcium supplements with your doctor.

Be aware that certain substances in your diet can reduce absorption, or increase calcium loss. These include [18]:

  • Antinutrients (phytic acid, oxalic acid) that bind calcium in the gut
  • Alcohol, which reduces calcium absorption and limits vitamin D production
  • Caffeine, since it reduces absorption and increases calcium loss

Plant-Based Diets

If you follow a vegan diet, you might be at a higher risk of certain nutrient deficiencies, including calcium and vitamin D. A carefully-planned vegan diet can be healthy and nutritious. Eat more vegetables high in calcium but low in oxalic acid, which inhibits calcium absorption. Good sources of calcium include [19, 20, 21]:

  • Tofu (calcium-set is best)
  • Kale, broccoli, sprouts, cauliflower, bok choy, collard greens

Some foods – such as fruit juices, soy or nut milk – are fortified with calcium.

Dairy-free Diets

If you follow a paleo-style or carnivore diet, you are probably avoiding dairy, soy, and nuts. This leaves you with fewer calcium rich-options. Good calcium sources for people on meat-heavy diets include [19, 22]:

  • Canned or fresh fish with bones (sardines, sardelles, or even salmon)
  • Beef tripe

Those on a more liberal paleo diet have additional sources to choose from, including kale, broccoli, bok choy, and other leafy greens.

Below is the RDA 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 unly 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

IMPORTANT: Not getting enough calcium in your diet may not show on your blood test. That’s because the bones will release more calcium into the blood to compensate. Testing bone mineral density and PTH levels, instead, can tell your doctor more about your calcium status.

4) Gut Disorders

Disorders and diseases that compromise calcium absorption in the gut can also lead to hypocalcemia. Examples include chronic diarrhea and inflammatory bowel diseases such as Chrons and ulcerative colitis [23, 10].

5) Abnormal Magnesium Levels

Magnesium deficiency is another factor that can lead to hypocalcemia. Without sufficient levels of magnesium, parathyroid hormone (PTH) cannot function properly. Magnesium is important for both the production and secretion of PTH [24, 25, 26].

On the other hand, a study suggests that high magnesium levels can also suppress PTH release, decreasing the calcium levels as a result [26].

6) High Phosphorus Levels

When phosphorus levels increase suddenly (e.g. in rhabdomyolysis or tumor lysis syndrome). Phosphorus binds calcium, decreasing active/ionized calcium levels [4].

7) Low Protein Levels

Low calcium levels are often caused by low protein levels, especially albumin. This is the case in [4]:

  • Liver disease
  • Alcoholism
  • Malnutrition
  • Infections

However, in these cases, the unbound (ionized) calcium remains normal. Therefore, your doctor can rule this out by checking your albumin or ionized calcium levels [4].

8) Menopause

During menopause, the body’s production of PTH, estrogen and other hormones changes. Due to a decrease in estrogen production, women are less able to retain calcium from dietary sources. Bone turnover (breakdown and replacement) rapidly increases and hypocalcemia is more common. Women also have a higher risk of osteoporosis after menopause [27, 28].

9) Kidney Disease

Kidney disease causes hypocalcemia since damaged kidneys retain less calcium and let more of it slip out into the urine. Damaged kidneys also produce less active vitamin D, which causes less calcium to be absorbed in the gut. Meanwhile, rising phosphate levels increase bound calcium and its flushing with the urine [10, 29].

10) Pancreatitis

Pancreatitis or pancreas inflammation is often accompanied by hypocalcemia, but the exact reason is unknown [30].

One theory is that lipopolysaccharides (LPS), toxins released from bacteria, end up in the bloodstream when the gut barrier is compromised. LPS cause calcium to accumulate in cells and tissues, leading to a drop in blood calcium levels [31].

11) Certain Drugs

Certain medications may cause (or contribute to) hypocalcemia. These include:

  • Bisphosphonates used to treat osteoporosis [32]
  • Anticonvulsants [33, 32]
  • Glucocorticoids, used to suppress inflammation [32]
  • Proton pump inhibitors, used to decrease stomach acid [32, 24]
  • Laxatives [34]

12) Genetic Disorders

Some rare genetic disorders can cause low calcium [35, 36].

Irregular Calcium Levels?

Chronic or severe hypocalcemia should always be treated by a doctor. There may be serious underlying medical conditions that can have dangerous consequences and require immediate treatment.

Further Reading

Source: https://selfhacked.com/blog/causes-of-calcium-deficiency/