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Submitted by Dr. Yasser Mokhtar,
MD. Dept. of internal medicine. School of medicine, University of South
Definition: It is abnormal
reduction in serum ionized calcium
(active form) and therefore the clinically relevant parameter.
Etiology of hypocalcemia
Absence of the Parathyroid Glands or of PTH
X-linked or autosomally inherited hypoparathyroidism
Autoimmune polyglandular syndrome type I
PTH gene mutations
Hypoparathyroidism after radioactive iodine thyroid
Impaired Secretion of PTH
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Vitamin D- Related Disorders
Vitamin D Deficiency
Impaired 1alpha -Hydroxylation
Excessive Deposition in the Skeleton
Hypocalcemia of any cause is associated with certain
typical signs and symptoms. Most prominent among these is increased neuromuscular
excitability. Paresthesias of the fingers, toes, and circumoral region
are mild manifestations; in more extreme cases there may be muscle cramping,
carpopedal spasm, laryngeal stridor, and convulsions. Symptoms reflect
not only the degree of hypocalcemia but also the acuteness of the fall
in serum calcium concentration. Patients with long-standing severe hypocalcemia
may show surprisingly few symptoms. Signs of latent tetany include Chvostek's
sign (twitching of the upper lip after tapping on the facial nerve below
the zygomatic arch) and Trousseau's sign (carpal spasm after inflating
a cuff on the upper arm above systolic blood pressure for 2 to 3 minutes).
Various mental disturbances, such as irritability,
depression, and even psychosis, have been attributed to hypocalcemia.
Papilledema and other signs of increased intracranial pressure have been
reported. Intracranial calcifications, particularly of the basal ganglia,
may be seen on plain radiographs and even more frequently on CT. Long-standing
hypocalcemia may lead to cataract formation. Cardiac effects of hypocalcemia
include a prolonged QT interval and, rarely, congestive heart failure.
Dental anomalies depend on age of onset; in children hypocalcemia can
cause enamel hypoplasia and failure of the adult teeth to erupt.
Diagnosis of hypocalcemia
Relies on the results of serum ionized calcium (below
8.5 mg%). Labs ordered should include Mg++, PO4--, PTH levels, kidney
functions in order to determine the origin.
Treatment of hypocalcemia
IV calcium gluconate (20 ml of 10%).
Continuous IV infusion in D5W.
Correction of magnesium
? Wilson: Williams
Textbook of Endocrinology, 9th ed., 1998.
? Harrison?s principles
of internal medicine, 14th ed., 1998.
? Goldman: Cecil Textbook
of Medicine, 21st ed.,2000.
? Washington Manual
of Medical Therapeutics, 30th ed., 2001.
? Uptodate version