Is there any need for re testing (additional laboratory) once a diagnosis of HAE is established?
Jul 6, 2015
Dr. C: A belated Happy Fourth of July. Thank you to Lois Perry of the HAEA for bringing up this topic. It had come to her attention that some physicians were requiring patients to come in for annual testing as a condition for renewing their prescriptions. As we reviewed in our last ‘Question of the Week’ for HAE type I & II this is an inherited condition that will not change once established within a family. The diagnostic testing (a low C4 level, low C1 inhibitor protein, and low C1 inhibitor functional level for Type I; low C4 level, normal C1 inhibitor protein, and low C1 inhibitor functional level for Type II) needs only to be done on a single occasion to establish the diagnosis. We unfortunately do not yet have a biomarker or test with the exception of mutations in the factor XII gene that accurately identifies HAE with normal C1 inhibitor. In an earlier Question of the Week we had discussed monitoring for individuals that had been exposed to attenuated androgens—Marc, what thoughts do you have about tests that should be done on a more routine basis?
: Once the diagnosis of C1INH-deficiency is definitively established by laboratory testing, there is no need to continue repeating C1INH levels for clinical management. Following C1INH levels over time hasn’t been shown to be useful in optimizing therapy – medications are adjusted based on clinical (symptom) response rather than tracking any predictive lab value. Labwork should certainly be repeated if the diagnosis is unclear (i.e. borderline or conflicting C4/C1INH results) and some consensus expert guidelines recommend getting 2 sets of labs several weeks apart in the case of abnormal C1INH levels on initial evaluation in order to be certain that the diagnosis of C1INH deficiency is correct. There are also safety labs that are recommended periodically with ongoing treatment in order to ensure the HAE medications used are not causing any adverse side effects. It’s definitely important that individuals with HAE follow-up with their physician periodically to review the efficacy and safety of their management plan, but repeating C1INH levels is generally not necessary as part of that follow-up evaluation.
Thank you, Marc. Independent of testing, how often do you think that patients with HAE should come in for follow up? Bruce, would you like to weigh in on this?
: The timing of follow-up visits will depend in part on how the patient is doing. I prefer to see my patients at least once every 6 months, but more frequently if they are continuing to have problems. Even if the patient is doing well, I find that it is important to regularly review what has happened since the last visit. This is also a good time to go over whether the treatment plan needs to be tweaked, discuss any new developments in the field, and answer questions. In addition to follow-up visits, it’s important that there is a regular and complete transfer of information between the patient and the physician. Patients should let their physicians know when they’ve needed to use an on-demand medicine to treat an attack so that the physician knows when they might need to consider alternatives. It’s also very helpful for patients to keep diaries of their symptoms and medicines and bring these diaries to the appointments.
: Thank you, management should indeed be a partnership between patients and physicians. Hopefully this information will be helpful for our readers. We look forward to your input, and will be back with our next ‘question of the week’.