Abstract
Dear Editor,
Chloroquine (or hydroxychloroquine hereafter referred to as chloroquine), is currently being speculated, amidst growing controversy, as a treatment method for SARS-CoV-2 (also known as COVID-19). 1 Exposure to chloroquine for individuals with disorders involving red blood cell function, such as glucose-6-phosphate dehydrogenase (G6PD) deficiency, increases their risk for severe hemolytic anemia. 2 In recent clinical trials for COVID-19 treatment with combined chloroquine and azithromycin, scientists have been cautious not to include G6PD-deficient patients. 3
G6PD contributes significantly to the formation of ribose 5-phosphate and the production of NADPH in mature red blood cells. G6PD deficiency is one of the most common enzyme deficiency-related diseases worldwide. Its prevalence ranges between 3.8% and 5.2% in Europe and the United States. The highest reported incidence is in sub-Saharan Africa (8.5%). The disorder is also common in the Mediterranean area (7.2%). 4 A study conducted in Lebanon in 2007 on a group of adult males showed that 22.2% of G6PD-deficient individuals were unaware of their condition. 5 It is indeed well documented that many affected individuals may be asymptomatic and, unless investigated, may remain oblivious of the disease.5–7 Environmental factors, including some types of food (such as fava beans in the Mediterranean variants) and medications such as anti-malarial drugs that exert excessive oxidative stress on the organism, can elicit an acute hemolytic anemia crisis, which would require blood transfusion. 7
In 1996, screening for G6PD deficiency was introduced as part of the national program for neonatal screening in Lebanon. It has been shown to be highly cost effective, 8 although nationwide implementation has been challenging with only 50% compliance over the total number of newborns. 9 Undiagnosed G6PD deficiency may be challenging for the treatment of COVID-19. Therefore, we recommend testing for G6PD deficiency before initiating chloroquine treatment in patients with COVID-19, in order to prevent unnecessary detrimental consequences. Awareness of a potential adverse outcome should be disseminated in view of the high tendency towards self-medication often described in the Lebanese public. 10
