Malignant Hyperthermia: testing

Anesthesiologists are likely to care for a patient with known MH susceptibility or a patient with a personal or family history of what could potentially have been MH. While definitive knowledge of whether a patient is MH susceptible would be extremely valuable when they present for surgery, testing for MH is not nearly as simple as drawing a CBC.

Currently, there are two methods to test for MH: genetic testing and the Caffeine Halothane contraction Test (CHCT) performed on a muscle biopsy.

Caffeine Halothane Contraction Test

The CHCT is the standard for MH susceptibility testing and like the name suggests is done by exposing muscle tissue to halothane and/or caffeine. Using a two-component test where specimens were exposed to caffeine or halothane the CHCT was found to have a sensitivity of 97% (95% CI, 84-100%) and specificity of 78% (95% CI, 69-85%).

What may limit patients from being tested is that the CHCT requires a fresh tissue sample. Thus, the patient must travel to one of the testing centers for the biopsy to be performed at that location.

Testing centers: Toronto Canada, Bethesda MD, Davis CA, Minneapolis MN, Winston-Salem NC.

Genetic Testing

Genetic testing consists of sending a blood sample to one of the testing centers listed below and screening for some of the mutations linked with MH. The RYR1 gene has been linked to MH; however, abnormalities in other muscle membrane proteins such as dihydropyridine receptor have also been linked. Thus, discussion with a genetic counselor is important to consider what testing is available, what mutations could be identified, etc. Additionally, the cost of genetic testing may or may not be covered under insurance which can prohibit potentially susceptible individuals from being tested.

Testing Centers: Marshfield WI, Atlanta GA, Buffalo NY, Minneapolis MN.