Calcium deficiency symptoms

Short answer

“Calcium deficiency” can describe two different things. Hypocalcemia is low blood calcium; the NIH defines it as serum below 8.5 mg/dL (2.12 mmol/L) or ionized calcium below 4.61 mg/dL (1.15 mmol/L), and it is mostly the result of a disease or a medicine. ^[1] Long-term inadequate intake, on the other hand, affects bone first, not the blood level. Symptoms differ in the two situations, and the diagnosis is made by blood test, not from symptoms.

What are the symptoms of low blood calcium (hypocalcemia)?

According to the review by Fong and Khan, the most common symptoms in hypocalcemia are paresthesias (tingling), muscle spasms, cramps, tetany, numbness around the mouth and seizures. Less often, laryngeal spasm, nerve-muscle excitability, cognitive impairment, personality changes, QT prolongation on ECG, ECG changes mimicking a heart attack, or heart failure may be seen. When hypocalcemia develops acutely, severe symptoms requiring hospital admission can occur; when it develops slowly, it is more likely to be symptom-free. ^[2]

The NIH also reports that hypocalcemia can be symptom-free, especially if mild or chronic, and that the most common symptom is increased nerve-muscle excitability (numbness around the mouth, tingling in the hands and feet, muscle spasms). More severe pictures can include kidney calcification or damage, brain calcification, neurological symptoms such as depression, cataract, heart failure, seizures and, rarely, coma. ^[1]

In a physician’s examination, Chvostek and Trousseau signs may be checked; Fong and Khan report that the Trousseau sign is present in 94% of hypocalcemic people and in only 1–4% of healthy people. These signs help diagnosis but do not establish it alone; the diagnosis is made by measuring albumin-corrected total calcium or ionized calcium. ^[2]

What causes hypocalcemia?

Hypocalcemia is spoken of when corrected total calcium is below 2.12 mmol/L; the most common causes are vitamin D insufficiency or resistance and parathyroid hormone (PTH) insufficiency. The review’s list also includes postoperative hypoparathyroidism, autoimmune or genetic hypoparathyroidism, vitamin D insufficiency due to kidney disease or end-stage liver disease, low or high magnesium, severe illness, and phosphate infusion or citrated blood transfusion. Medicines such as bisphosphonates, cisplatin, antiepileptics, aminoglycosides, diuretics and proton pump inhibitors have also been associated with hypocalcemia. ^[2]

Hypoparathyroidism is most often seen after inadvertent removal of or damage to the parathyroid glands during thyroid surgery; the review reports this in 0.5–6% of total thyroidectomies and states that hypocalcemia persisting 6 months after surgery confirms the diagnosis in the presence of low or inappropriately normal PTH. ^[2]

The NIH, for its part, says hypocalcemia is usually the result of vitamin D or magnesium deficiency, impaired PTH production (hypoparathyroidism), impaired calcium release from bone, severe illness, or some medicines (bisphosphonates, cisplatin, proton pump inhibitors). ^[1] That is, the source of the problem is often not diet but a disorder in the regulation of calcium.

Detailed guideVitamin D deficiency symptoms: what is meaningful, what is not?→ Detailed guideMagnesium deficiency symptoms and what the test means→

What does low calcium intake lead to?

Because blood calcium is tightly regulated, serum level does not reflect nutritional status; the body uses bone as a store for calcium, and 98% of calcium is in bone. Bone mass, in turn, is assessed by dual-energy X-ray absorptiometry (DXA). ^[1] The NIH states that calcium deficiency can reduce bone strength and lead to osteoporosis, rickets in children, and osteomalacia in children and adults, but that rickets and osteomalacia are caused mostly by vitamin D deficiency. ^[1]

The relationship between intake and fracture within the usual intake range is a separate question. The systematic review by Bolland and colleagues (participants over 50) addressed two questions separately. For dietary calcium there were 44 cohort studies and only two small randomized trials (262 participants); in most cohorts no association was found between intake and fracture, and there was no clinical trial evidence that increasing intake from food prevents fracture. For supplements (with or without vitamin D) there were 26 randomized trials; in the 20 trials reporting total fracture (58,573 people) a small reduction was seen (RR 0.89; 95% CI 0.81–0.96), while there was no reduction in hip fracture (RR 0.95; 0.76–1.18). There were signs of publication bias, and in the four trials with the lowest risk of bias (44,505 participants) no effect on fracture risk was seen at any site. The only trial that significantly reduced fracture was conducted in frail older women living in a care home with low dietary calcium intake and low vitamin D levels. The authors found the evidence that supplements prevent fracture weak and inconsistent. ^[4]

Who is at higher risk of low intake?

The NIH lists postmenopausal women and those who avoid dairy products as groups more likely to have inadequate intake. In postmenopausal women, decreased estrogen reduces calcium absorption and increases urinary calcium loss and release of calcium from bone; women lose on average about 1% of bone density per year after menopause, and about 30% of postmenopausal women in the US and Europe have osteoporosis. For this reason the US reference is 1,200 mg for women over 51. People who do not consume dairy products because of lactose intolerance, milk allergy or a vegan diet are also at higher risk of inadequate intake. ^[1]

Absorption also changes with age: according to the NIH, net absorption of food calcium rises to as much as 60% in infants and young children, falls to about 25% in adulthood, and continues to decline with age. ^[1] Fong and Khan report that in vitamin D insufficiency, intestinal absorption can fall by as much as 50% and in this case only 10–15% of food calcium is absorbed; this is why the coexistence of low intake and vitamin D insufficiency is important. ^[2]

In Türkiye, the T.C. Ministry of Health publication “Calcium, Vitamin D and Osteoporosis” gives daily calcium recommendations derived from the Türkiye-Specific Dietary Guidelines (2006) as follows: for adults, 1,000 mg at ages 19–50 and 1,200 mg at 51 and over; 1,300 mg for pregnant women; for lactating women, 1,300 mg under age 18 and 1,000 mg over 19. These values belong to an older national publication, separate from the NIH and EFSA references. ^[3]

Which tests are done, and in whom are they considered?

According to the list by Fong and Khan, the basic tests when hypocalcemia is suspected are albumin-corrected serum calcium, phosphate, magnesium, electrolytes, creatinine, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, blood pH and complete blood count; in addition, tests such as ionized calcium and 24-hour urine calcium, phosphate, magnesium and creatinine may be requested. The review also states that the neck should be examined for a surgical scar on physical examination, because patients may not remember a distant neck operation. ^[2] This list is aimed at physicians; no conclusion about calcium level can be drawn at home by looking at a single symptom.

In which situations is urgent assessment needed?

Acute hypocalcemia can cause severe symptoms. Fong and Khan report that intravenous calcium is given when serum calcium falls below 1.9 mmol/L, when ionized calcium is below 1 mmol/L or when the person is symptomatic (based on expert opinion, level of evidence III). ^[2] Symptoms such as tetany, seizure, laryngeal spasm, change in heart rhythm or clouding of consciousness therefore require urgent medical assessment. This page gives no treatment plan; supplement and medication decisions are made together with a physician.

Detailed guideCalcium guide: roles, reference intakes and supplement safety→ Detailed guideHigh calcium (hypercalcemia): causes, symptoms and tests→ Detailed guideWhich foods contain calcium? Serving table and absorption→

Main guide: What is calcium? This guide does not recommend personal doses.