How is MH definitively diagnosed?
The search for a simple diagnostic blood test of MH continues. Genetic testing presently detects 50% of cases in families with known genetic mutations. Therefore, skeletal muscle biopsy remains the gold standard of MH diagnosis. Elevated serum CPK in a close relative of a patient with known MH is diagnostic of MH in 70–80% of cases. Normal values, however, do not rule out the diagnosis; consequently, such relatives must be tested.
A sizable muscle biopsy is taken under local anesthesia. The specimen is exposed to caffeine, halothane, or a com-bination of the two. Unfortunately, the caffeine–halothane contracture test is not standardized in centers around the world, and false-positives and to a lesser extent false-negatives occur.