Hypocalcemia with elevated parathyroid hormone (PTH) can be caused by vitamin D deficiency or resistance, post-renal transplant or parathyroid surgery, vitamin D therapy for rickets, medullary thyroid carcinoma, pancreatitis, alcohol use disorder, a need for massive blood transfusion (due to citrate chelation), and rhabdomyolysis. Hypocalcemia can be drug-induced by medications including anticonvulsants, corticosteroids, barbiturates (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 women, 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, human immunodeficiency virus, or autoimmune hypoparathyroidism.
The presentation of acute hypocalcemia ranges from asymptomatic to life-threatening. Severe hypocalcemia is characterized by neuromuscular irritability (tetany). This may include seizures, paresthesias, facial muscle tics (Chvostek sign), laryngospasms, bronchospasms, and carpopedal spasms (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 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