Magnesium levulinate, the magnesium salt of levulinic acid, is a mineral supplement. It has been shown that in some cases of congenital non-spherocytic haemolytic anaemia (CNSHA) with pyruvate kinase deficiency, the primary defect may be related to diminished magnesium-stimulated ATPase activity, followed by elevation of the erythrocyte ATP level. In CNSHA patients the administration of Magnesium levulinate was followed by an increase in PK activity almost to the control value. This may indicate that magnesium ions stimulate deficient ATPase activity and lead to diminution of ATP as a negative effector for other regulatory enzymes.