Hypocalcemia Definition

Hypocalcemia is a type electrolyte imbalance in which the calcium levels in the blood are lower than the normal values [1]. The normal serum calcium levels range from 8.5 mg/dL to 10.5 mg/dL [2].

Calcium Homeostasis

  • Calcium is one of the most numerous electrolytes present in the body. This electrolyte performs vital roles in cellular functions, neurotransmission, musculoskeletal functions, and blood homeostasis [3].
  • Its regulation is maintained by the parathyroid hormone (PTH), calcitonin and vitamin D. It is also affected by other electrolytes such as magnesium and phosphorus.
  • Normally, the food ingested that contains calcium undergoes absorption at the intestines. Then, later on, it is excreted in the urine. Even if the body consumes calcium-rich foods, the calcium levels are still regulated.

1. Parathyroid Hormone (PTH)

  • This stimulates the bone reabsorption of calcium.
  • Responsible for mediating the absorption of calcium in the intestines.

2. Vitamin D

  • Plays a role in controlling the release of PTH
  • Facilitates the stimulation of bone reabsorption by the PTH
  • Triggers the absorption of calcium in the intestines

3. Calcitonin

  • Maintains balance by lowering the calcium levels by addressing losses at the bone, GI, and renal sites.[4]

Calcium Metabolism picture

Picture 1: Calcium Metabolism
Source: en.wikipedia.org

Hypocalcemia Causes

When the body is in the hypoglycemic condition, 40% of the serum plasma is bound or attached to albumin. The remaining serum calcium fractions are unbound or free. These are referred to as ionised calcium. The ionised percentage of calcium is important because these are physiologically active [5].

The level of calcium circulating in the body can be influenced by different factors and can be impaired by imbalances in the absorption, distribution, and excretion of calcium [3].

The following are the common causes of hypocalcemia:

Parathyroid Hormone Imbalances

1. Absent/Low Levels of Parathyroid Hormone (Hypoparathyroidism)

  • Parathyroid destruction: This may be caused by factors such as radiotherapy, metastases, systemic diseases, or surgery.
  • Lowered secretion of parathyroid hormones: Results from neonatal hypocalcemia (associated to maternal hypercalcemia), hungry bone disease (occurs after the performance of parathyroidectomy to the patient), gene defects.
  • Hypomagnesemia/Hypermagnesemia

2. Elevated Parathyroid Hormone Levels

  • Inadequate vitamin D: Lack of sunlight exposure, malabsorption, nutritional deficiency, liver diseases, chronic kidney disease, post-gastric bypass surgery.
  • Vitamin D resistance: Particularly in rickets, Fanconi’s syndrome (renal tubular dysfunction)[5, 6]

Other Electrolyte Imbalances

1. Magnesium imbalances

  • Hypomagnesemia
  • Severe hypermagnesemia

2. Phosphorus imbalances

  • Hyperphosphatemia: Tumor lysis syndrome, renal failure, rhabdomyolysis, phosphate administration


1. Widespread osteoblastic metastases

  • Breast Cancer
  • Prostate Cancer

2. Tumor lysis

  • Caused by chemotherapy[7]

Medications/Treatment Related

1. Antimicrobials

  • Ketoconazole
  • Foscarnet
  • Pentamidine

2. Blood transfusion

  • Rapid infusion of blood which contains high levels of citrate

3. Chemotherapy agents

  • Leucovorin
  • Cisplatin
  • 5-Fluorouracil

4. IV therapy

  • IV fluid administration post-surgery
  • IV biphosphonate thrapy in patients who are deficient in vitamin D

5. Others:

  • Anticonvulsants
  • Hypercalcemic agents: Calcitonin
  • Chelation therapy: EDTA
  • Gadolinium-based contrast agents used in MRI/MRA (done in chronic renal failure patients)
  • Prolonged use of laxatives and other medications that contain magnesium [1, 6, 7, 8]

Other causes

  • Sepsis
  • Toxic Shock syndrome
  • Alkalosis (hyperventilation)[1, 6, 7]

Hypocalcemia Symptoms

Acute Hypocalcemia

1. Neuromuscular Symptoms

  • Seizures
  • Circumoral and acral paresthesias: Occurs at the fingers, toes, and around the mouth
  • Muscle stiffness and spasms
  • Chvostek’s sign
  • Trousseau’s sign

2. Neurospychiatric Symptoms

  • Emotional problems: Involves depression, anxiety, irritability
  • Cognitive impairment: May cause inability to concentrate and brain fogging
  • Memory impairment

3. Cardiovascular Symptoms

  • Hypotension (Low blood pressure)
  • Prolonged QT interval
  • Cardiac Arrhythmias
  • Congestive Heart Failure

4. Autonomic Symptoms

  • Diaphoresis
  • Biliary colic
  • Bronchospasm/Laryngospasm

5. Other symptoms

  • Dysphagia (Difficulty in swallowing)
  • Difficulty in speaking: Characterized by raspy-like voice
  • Dermatologic problems: Eczema, dermatitis, dry coarse skin, hyperpigmentation
  • Gastrointestinal problems: Steatorrhea, Gastric achlorhydia

Chronic Hypocalcemia

1. Neuropsychiatric Symptoms

  • Memory loss or Demetia (for adults), Mental retardation (for children)
  • Confusion
  • Extrapyramidal symptoms (Usually parkinsonism)
  • Calcifications occurring at the basal ganglia

2. Dermatologic and dental problems

  • Dry coarse skin
  • Brittle nails
  • Abnormal teeth

3. Ophthalmic problems

  • Papilloedema
  • Cataract

4. Kidney problems

  • Kidney stones[5, 7, 9]

Hypocalcemia in Newborns

In newborns, hypocalcemia is termed as Neonatal Hypocalcemia. It is divided into two, according to its onset. These are:

  • Early Hypocalcemia: This occurs within the first three days of the newborn’s life.
  • Late Hypocalcemia: The onset is usually from fifth to tenth days of life. This occurs most commonly following several days of giving formula feedings to the baby. This is associated with some formulas which contain high levels of phosphate that causes the lowering of the serum calcium levels.[11]

Neonatal Hypocalcemia Causes

  • Prematurity (babies who were born early) and low birth weight
  • Diabetic Mother
  • Dystocia (difficult birth)
  • Episodes of hypoxia (low oxygenation level)
  • Stress due to severe illness
  • Infection
  • Certain medications[11, 12]

Neonatal Hypocalcemia Symptoms

In some newborns, the symptoms of hypocalcemia may not be noticed. However, the symptoms occurring in newborns and its onset vary. Here are some of the symptoms of hypocalcemia in newborns:

  • Poor feeding
  • Lethargy
  • Irritability, jitteriness
  • Tremors, muscle twitches
  • Seizure[11]

Calcium intake of newborns image

Picture 2: Calcium intake of newborns
Source: endotext.org

Hypocalcemia Treatment

The approach used in treating hypocalcemic patients is influenced by factors such as severity, cause, symptoms, and its onset. The following are the managements used in treating hypocalcemia:

Medical Management

1. Mild Hypocalcemia

  • Dose of supplemental calcium for healthy individuals: 1-3 g/day
  • Outpatient treatment: Oral calcium supplement
  • Admitted patients: IV replacement therapy

2. Severe Hypocalcemia

  • Supportive Treatment: Oxygen administration, IV fluid replacement (symptomatic patients), close monitoring
  • Dose of supplemental Calcium: 100-300 mg
  • 10 mL of Calcium Chloride incorporated in 5% dextrose in water (50-100 mL)
  • Digoxin therapy: Indicated for patients who have cardiac arrhythmias
  • Oral Calcium and Vitamin D: Particularly in patients who are in post-parathyroid surgery status.

3. Chronic Hypocalcemia

  • Calcitriol: Active form of vitamin D
  • Oral calcium supplements
  • Sunlight exposure[10]

Dietary Management

1. Foods rich in calcium

  • Tofu, dairy products, green leafy vegetables, almonds, dried herbs, etc.
  • Recommended dietary calcium: 1g per day

2. Low dietary intake of phosphorus

  • Limited to 400-800 mg per day
  • This to prevent hyperphosphatemia.
  • Advised in hypocalcemic patients, especially those who have chronic renal failure[10, 11]

Hypocalcemia Exams and Tests

Patient Health History

Determined by the health care provider to pinpoint the underlying cause of hypocalcemia. Some questions regarding symptoms may be asked.[7]

Physical Assessment

The doctor will assess for any present symptoms manifested by the patient. The most common noted signs of hypocalcemia are:

1. Chvostek’s sign

  • Elicited by tapping the location of the facial nerve (Located below the zygomatic arch, just in front of the ears)
  • Positive Chvostek’s sign: As the tapping on the facial nerve is done, twitching of the facial areas, specifically, nose, mouth, and cheek will occur.

Chvostek’s sign picture

Picture 3: Chvostek’s sign
Source: quizlet.com

2. Trousseau’s sign

  • This occurs due to neuromuscular excitability.
  • To determine the presence of this, a blood pressure cuff will be needed.
  • The blood pressure cuff will be wrapped and pumped up until the patient’s systolic level. Then, it is kept at that pressure for several minutes.
  • Positive Trousseau’s sign is indicated when carpopedal spasm occurs. This is the flexion of the metacarpophalangeal joints, and wrist, adduction of fingers and thumbs, as well as extension of the interphalangeal joints.
  • Paresthesias located at the fingers may also be felt by the patient.[5]

Trousseau’s sign image

Picture 4: Trousseau’s sign
Source: medicalmystery.org

Laboratory Work-Ups

1. Serum Ionized Calcium

  • Most definitive diagnostic test for hypocalcemia.
  • A serum calcium level below 8.5 mg/dL indicates hypocalcemia.

2. Serum Electrolytes

  • Includes checking of serum Phosphorus and Magnesium

3. Parathyroid Hormone Level

  • Classified as an anti-body-mediated radioimmunoassay.
  • This should be performed as soon as possible to a patient with hypocalcemia.

4. Vitamin D metabolites

  • In most hypocalcemic patients, vitamin D is suspected.
  • Measures 1,25 (OH)2 D and 25 (OH) D
  • Deficiency in 1,25 (OH)2 D, when combined with high PTH levels, indicates ineffectiveness of the PTH. This is common in patients with chronic renal failure and rickets.
  • On the other hand, lack of 25 (OH) D is suggestive of Vitamin D insufficiency caused by malabsorption, lack of its nutritional intake, and lack of sunlight exposure.

Imaging Studies

1. Electrocardiogram

Common findings include: Prolonged QT interval, decreased myocardial contractility, and ventricular dysrhythmias. [10]

ECG showing ventricular dysrhythmia picture

Picture 5: ECG showing ventricular dysrhythmia
Source: physio-pedia.com


  1. http://en.wikipedia.org/wiki/Hypocalcaemia
  2. http://www.livestrong.com/article/262998-normal-calcium-levels-in-blood/
  3. http://bestpracticedx.bmj.com/best-practice/monograph/160.html
  4. http://emedicine.medscape.com/article/241893-overview#a0104
  5. http://www.patient.co.uk/doctor/Hypocalcaemia.htm
  6. http://www.endotext.org/parathyroid/parathyroid7/parathyroid7.htm
  7. http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/endocrinology/hypocalcemia/
  8. https://www.clinicalkey.com/topics/endocrinology/hypocalcemia.html
  9. https://www.hypopara.org/support-services/newly-diagnosed/what-is-hypocalcemia.html
  10. http://emedicine.medscape.com/article/241893-treatment#aw2aab6b6b5
  11. http://www.chp.edu/CHP/P02376
  12. http://umm.edu/health/medical/ency/articles/hypocalcemia-infants

Published on by under Diseases and Conditions.
Article was last reviewed on September 25th, 2017.

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