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Nonimmune Hemolytic Anemia. Most etiologies of nonimmune hemolytic anemia
require observation and supportive care, including removal of the offending agent and
prevention of renal damage due to significant hemolysis (see Table 93.3 ). Infectious
agents that may induce hemolytic anemia include malaria, other protozoa, and a wide
variety of gram-positive and gram-negative organisms. Hemolysis secondary to
infection requires rapid identification and prompt treatment. When hemolysis is a result
of small-vessel disease, treatment of the underlying disorder (e.g., collagen vascular
disease) or primarily affected organs (e.g., renal failure in hemolytic-uremic syndrome)
is the first priority. The prompt institution of plasma exchange for TTP can be
lifesaving.
Clinical Indications for Discharge or Admission
Hospitalize patients with severe or symptomatic anemia or an unclear clinical trajectory
for close clinical monitoring and treatment. Frequently, a critical care setting is
appropriate for these patients. Consider outpatient management in patients with a clear
or well-established underlying diagnosis and mild anemia with short-interval follow-up
for monitoring and ongoing management.

METHEMOGLOBINEMIA
Goals of Treatment
Methemoglobin (MHb) is the end product of a number of mechanisms (toxic exposure,
dietary trigger, acidosis, genetic abnormality) that oxidize the iron associated with a
heme group from the ferrous (Fe2+ ) to ferric state (Fe3+ ) rendering it unable to
reversibly bind oxygen. In high quantities, insufficient gas exchange may be
incompatible with life. The primary goal of treatment is to remove the causative agent,
provide supportive care to optimize end-organ oxygenation, and allow time for
reduction of MHb back to hemoglobin. In symptomatic and life-threatening situations,
therapeutic intervention can hasten the reduction process.
CLINICAL PEARLS AND PITFALLS
Suspect MHb when a cyanotic patient has a normal arterial PO2 , and pulse
oximetry (generally in the mid 80s) is significantly lower than the oxygen
saturation reported on arterial blood gas.

MHb levels are reported as percent of total hemoglobin; therefore, patients
with anemia will manifest more symptoms at lower levels of MHb.
Methylene blue administration for methemoglobinemia is contraindicated in
patients with G6PD.

Clinical Considerations