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Contributors: Casey Silver MD, Abhijeet Waghray MD
Other Resources UpToDate PubMed


Hypocalcemia is a condition of low serum calcium concentration and, specifically, low levels of ionized (nonprotein-bound) calcium. Causes can be differentiated by low parathyroid hormone (PTH) levels or high PTH levels.

Hypocalcemia with elevated PTH can be caused by vitamin D deficiency (rickets) or resistance, postrenal transplant or parathyroid surgery, medullary thyroid carcinoma, pancreatitis, alcohol use disorder, a need for massive blood transfusion (due to citrate chelation), or rhabdomyolysis. Hypocalcemia can be drug-induced by medications including anticonvulsants, corticosteroids, barbiturates (in elderly patients), bisphosphonates, calcitonin, methicillin, mithramycin, colchicine, estrogens, and glutethimide. Ethylene glycol poisoning, fluoride poisoning, and vitamin A intoxication are other possible causes. In pregnant patients, tetracycline can contribute to hypocalcemia.

Hypocalcemia with decreased PTH can be caused by genetic disorders, hemosiderosis, Wilson disease, DiGeorge syndrome, hungry bone syndrome, thyroid or parathyroid surgery, parathyroid radiation therapy, HIV, or autoimmune hypoparathyroidism.

The presentation of acute hypocalcemia ranges from asymptomatic to life-threatening. Severe hypocalcemia is characterized by neuromuscular irritability (tetany). Other symptoms include seizure, paresthesia, facial muscle tics (Chvostek sign), laryngospasm, bronchospasm, and/or carpopedal spasm (Trousseau sign). Other signs and symptoms include papilledema and cardiac irregularities including arrhythmias, hypotension, prolonged QT interval, or heart failure.

Chronic hypocalcemia findings range from ectopic calcification (basal ganglia), dry skin, cataracts, and dental anomalies to neurological findings of dementia, parkinsonism, or extrapyramidal signs.

Infants with hypocalcemia are mostly asymptomatic. Some may present with neuromuscular irritability with muscle twitching or may have clonic seizures. Rarely laryngospasm, bronchospasm, or pylorospasm may be present, and there may be findings of inspiratory stridor, wheezing, or vomiting.

Management primarily involves supplementation with oral or intravenous (IV) formulations of calcium. Choice of formulation and route of administration depends on clinical severity and types of access available.


E83.51 – Hypocalcemia

5291005 – Hypocalcemia

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Differential diagnosis for patients with hypocalcemia is divided into high PTH and low PTH etiologies. Postsurgical hypoparathyroidism, autoimmune hypoparathyroidism, and vitamin D deficiency are most common.

Low PTH:
  • Primary or secondary Hypoparathyroidism, such as following thyroid surgery
  • Hypoalbuminemia
  • Acid-base disturbances
High PTH:
  • Vitamin D deficiency
  • Chronic kidney disease
  • Pseudohypoparathyroidism type 1A (PTH resistance)
  • Hyperphosphatemia
  • Acute pancreatitis
  • Large-volume transfusion
  • Drugs

Best Tests

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:01/07/2019
Last Updated:08/12/2021
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A medical illustration showing key findings of Hypocalcemia (Chronic) : Dry skin, Muscle weakness, Myalgia, Ca decreased, Confusion
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