Asplenia refers to the absence of normal spleen function and is associated with some serious infection risks. Hyposplenism is used to describe reduced (hypo-) splenic functioning, but not as severely affected as with asplenism. Functional asplenia occurs when splenic tissue is present but does not work well (e.g. sickle-cell disease, polysplenia) -such patients are managed as if asplenic-, while in anatomic asplenia, the spleen itself is absent. Causes
Congenital
Congenital asplenia is rare. There are two distinct types of genetic disorders: heterotaxy syndrome and isolated congenital asplenia. polysplenia

Acquired
Acquired asplenia occurs for several reasons:

Following splenectomy due to splenic rupture from trauma or because of tumor
After splenectomy with the goal of interfering with splenic function, as a treatment for diseases (e.g. idiopathic thrombocytopenic purpura, thalassemia, spherocytosis), in which the spleens usual activity exacerbates the disease
After splenectomy with the goal of arresting the progression of cancers (Chronic lymphocytic leukemia, Hodgkins disease (starting in the 1970s), non-Hodgkin lymphoma)
Due to underlying diseases that destroy the spleen (autosplenectomy), e.g. sickle-cell disease. Celiac disease: unknown physiopathology. In a 1970 study, it was the second most common cause of abnormalities of red blood cells linked to hyposplenism, after surgical splenectomy. Functional asplenia
Functional asplenia can occur when patients with metabolic or haematological disorders have their splenic tissue organisation altered. This can lead to results similar to those seen in patients who have undergone a splenectomy e.g. becoming infected with encapsulated bacteria such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis.
Individuals not taking MAOIs may consume at least 2 grams of tyramine in a meal and not experience an increase in blood pressure, whereas those taking MAOIs such as tranylcypromine may experience a sharp increase in blood pressure following consumption of as little as 10 mg of tyramine, which can lead to hypertensive crisis.Foods containing tyramine include aged cheeses, cured meats, tofu and certain red wines. Some, such as yeast extracts, contain enough tyramine to be potentially fatal in a single serving. Spoiled food is also likely to contain dangerous levels of tyramine. Adverse effects
Incidence of adverse effectsVery common (>10% incidence) adverse effects include:

Dizziness secondary to orthostatic hypotension (17%)Common (1-10% incidence) adverse effects include:

Tachycardia (5–10%)
Hypomania (7%)
Paresthesia (5%)
Weight loss (2%)
Confusion (2%)
Dry mouth (2%)
Sexual function disorders (2%)
Hypertension (1–2 hours after ingestion) (2%)
Rash (2%)
Urinary retention (2%)Other (unknown incidence) adverse effects include:

Increased/decreased appetite
Blood dyscrasias
Chest pain
Diarrhea
Edema
Hallucinations
Hyperreflexia
Insomnia
Jaundice
Leg cramps
Myalgia
Palpitations
Sensation of cold
Suicidal ideation
TremorOf note, there has not been found to be a correlation between sex and age below 65 regarding incidence of adverse effects.Tranylcypromine is not associated with weight gain and has a low risk for hepatotoxicity compared to the hydrazine MAOIs.It is generally recommended that MAOIs be discontinued prior to anesthesia; however, this creates a risk of recurrent depression. In a retrospective observational cohort study, patients on tranylcypromine undergoing general anesthesia had a lower incidence of intraoperative hypotension, while there was no difference between patients not taking an MAOI regarding intraoperative incidence of bradycardia, tachycardia, or hypertension.