0071643192.pdf

■ Ca^2 +has a host of critical functions, including:
■ Control of cell membrane depolarization
■ Coagulation and platelet aggregation
■ Hormone secretion
■ Contractile protein function
■ Intracellular enzyme regulation
■ Drops in pH increase levels of ionized calcium because Ca^2 +binds to pro-
tein in place of H+. This is known as relative hypercalcemia.
■ The same relative hypercalcemia occurs with hypoalbuminemia with no
change in total calcium.

Hypocalcemia (Ca^2 +<8.5 mg/dL)

SYMPTOMS

■ Parasthesias, particularly perioral and distally
■ Muscle spasms, particularly carpopedal
■ Seizures

EXAM

■ Hyperreflexia
■ Chvostek sign (spasm when tapping along the facial nerve)
■ Trousseau sign (arm spasm when BP inflated)
■ Cardiovascular findings
■ Hypotension due to loss of vascular tone
■ CHF
■ Arrhythmias
■ QT prolongation

CAUSES

■ Vitamin D disorder
■ Malabsorption of Vitamin D from chronic diarrhea
■ Impaired production of 1,25-dihydroxy vitamin D, usually secondary to
renal or hepatic failure or anticonvulsants
■ Hypoparathyroidism
■ Hypomagnesemia
■ Acute pancreatitis as fat binds calcium
■ Alkalosis, either respiratory or metabolic
■ Rapid and massive blood transfusions
■ Rhabdomyolysis
■ Drugs: Dilantin, cimetidine, steroids, foscarnet, and anticonvulsants

TREATMENT

■ Emergent treatment of acutely symptomatic patients with 10% calcium
chloride
■ Transfusion-associated hypocalcemia is transient in most patients and will
resolve without treatment. Since citrate is metabolized through the liver,
patients with liver disease may require calcium during transfusions.

Hypercalcemia (Ca^2 +>10.5 mg/dL)

Hypercalcemia is generally a product of another underlying disorder and not
a primary process in itself.

ENDOCRINE, METABOLIC, FLUID, AND

ELECTROLYTE DISORDERS

Hypocalcemia can protect

against digitalis toxicity;

treatment of hypocalcemia

can expose digitalis toxicity.