Internal Medicine

0521779407-09 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:54

Hypokalemia Hypomagnesemia 789

➣cardiac: palpitations secondary to ventricular arrhythmia

EKG changes: U waves, ST-segment depression, widening, flat-

tening, or inversion of T waves

➣hypokalemia is generally readily treatable and has good progno-

sis

➣some causes of hypokalemia require chronic therapy with oral K

and K sparing diuretics

spironolactone in high doses can cause gynecomastia

Hypomagnesemia....................................

STANLEY GOLDFARB, MD

history & physical

History

■Usually diagnosed with screening lab tests. Symptoms include apa-

thy, depression, some or all facets of delirium, seizures, paresthesias.

Signs & Symptoms

■Tremor of extremities and tongue, myoclonic jerks, Chvostek sign

(common), Trousseau sign (rarely), tetany (rarely unless concomi-

tant hypocalcemia), general muscular weakness (particularly respi-

ratory muscles), coma, vertigo, nystagmus and movement disorders

(rarely).

tests

Laboratory

Blood Tests:

■Determining Magnesium Deficiency

■Only parameter to consistently predict magnesium depletion is

retention of >75% of magnesium after a magnesium infusion.

■A low serum magnesium level is the parameter that prompts therapy.

■A very low serum value (<1 mg/dl) always indicates significant

deficits that require therapy.

■Other findings:

■Refractory hypocalcemia responsive only to magnesium therapy

■Refractory hypokalemia responsive only to magnesium therapy

ECG

■Increased susceptibility to digoxin-related ventricular arrhythmias:

premature ventricular contractions, ventricular tachycardia, tor-

sades de pointes, ventricular fibrillation