HIT(T): Duration of Anticoagulation

  • Bilateral lower extremity compression ultrasonography may be considered in patients with HIT, whether or not there is clinical evidence of lower-limb DVT, because silent DVT is common and its presence may influence the recommended duration of anticoagulation.
  • For patients with HIT-associated thrombosis (i.e. HITT), anticoagulate for a defined course (typically 3 months) as with other provoked thromboses.
  • For patients with HIT without thrombosis (i.e. isolated HIT), the optimal duration of anticoagulation is unknown. Because there is an elevated risk of thrombosis extending 2 to 4 weeks after heparin is stopped, anticoagulation for up to 4 weeks should be considered.
  • For all patients, anticoagulation management should be based on an individualized risk/benefit assessment.

Common Variable Immunodeficiency

CVID is a rare form of severe antibody deficiency with an incidence of 1 in 25,000 to 1 in 100,000. The mean age of diagnosis is 30 years, although there can be a delay in diagnosis by many years as demonstrated in our patient. The disorder results from failed B-cell differentiation. Thus, plasma cells do not develop and immunoglobulin secretion is impaired. A number of defects of T-cell function and deficits in the memory B-cell pool have been identified, but the underlying cause of this defect remains unknown.

CVID has variable clinical manifestations, the most common being recurrent bacterial infections caused by encapsulated bacteria [1]. Bacterial infections commonly involve the sinuses and respiratory tract leading to sinusitis, otitis media, bronchitis and pneumonia. Chronic sinusitis and bronchiectasis are frequent complications in untreated patients leading to significant morbidity and mortality. Giardiasis is a frequent infection in patients leading to chronic diarrhea. They can also have diarrhea secondary to dysgonic fermenter 3, which is unusual in immunocompetent patients. They are prone to severe herpes simplex, cytomegalovirus infections of the gastrointestinal tract and meningoencephalitis from enteroviral infection. Patients who are not receiving IVIG owing to a delay in diagnosis may develop sepsis or meningitis, which can be fatal. These patients are also at higher risk of developing other autoimmune diseases such as thrombocytopenic purpura, hemolytic anemia and/or neutropenia. In the largest published case series of 248 patients, a 7.7% incidence of non-Hodgkin’s lymphoma (NHL) was reported. Mucosal associated lymphoid tissue lymphomas, an uncommon form of NHL, can occur in these patients in the stomach or bronchial tissue. Other uncommon manifestations include granulomatous lung disease, follicular bronchiolitis, inflammatory bowel disease, sprue-like illness, nodular lymphoid hyperplasia and lymphoid interstitial pneumonia.

CVID should be suspected in any patient with recurrent infections, especially of the upper or lower respiratory tract. IgG, IgA or IgM levels should be less than two standard deviations below the mean for age-adjusted standardized reference. They should also have inadequate antibody response to pneumococcal vaccine and tetanus toxoid or absent isohemagglutinins to confirm the diagnosis.

The mainstay of treatment is IVIG. The target trough level should be 400–500 mg/dl, which is achieved by infusing a dose of 200–400 mg/kg every three or four weeks. The dosage varies from patient to patient, and IgG levels should be checked periodically to attain a target trough level. Autoimmune and granulomatous components of this disease do not respond to treatment with IVIG. There has been recent interest in the use of tumor necrosis factor (TNF) antagonists and anti-CD20 immunomodulators in treating autoimmune and granulomatous diseases based on the dramatic improvement of some clinical manifestations documented in some case reports. However, long-term immunomodulators should be used with extreme caution as these patients are at high risk of developing malignancies.

Journal of Medical Case Reports 2008, 2:117