There have been calls to reclassify sickle cell trait as a disease state, based on its malignant clinical presentations. Significance may be greater during exercise. Association with other medical conditions
Malaria
The sickle cell trait provides a survival advantage against malaria fatality over people with normal hemoglobin in regions where malaria is endemic. The trait is known to cause significantly fewer deaths due to malaria, especially when Plasmodium falciparum is the causative organism. This is a prime example of natural selection, evidenced by the fact that the geographical distribution of the gene for hemoglobin S and the distribution of malaria in Africa virtually overlap. Because of the unique survival advantage, people with the trait become increasingly numerous as the number of malaria-infected people increases. Conversely, people who have normal hemoglobin tend to succumb to the complications of malaria.The way in which sickle cell protects against malaria is attributed to several different things. One of the more common explanations is that the sickle hemoglobin inhibits the plasmodium parasite from infecting the red blood cells which reduces the number of malaria parasites to infect the host. Another factor is the production of heme oxygenase-1 (HO-1) enzyme, which is highly present in the sickle hemoglobin. This enzyme produces carbon monoxide which has been proven to protect against cerebral malaria. Established associations
Hematuria
Hyposthenuria
Renal medullary carcinoma, a cancer affecting the kidney, is a very rare complication seen in patients with sickle cell trait. Renal papillary necrosis (only considered "possible" by some sources)
Splenic infarcts at high altitude. Surgery may not always be necessary.
Deformability of the erythrocytes that cause the microcirculatory distress can be demonstrated through various other hemorheological characteristics. In order to determine the deformability of erythrocytes multiple factors including blood and plasma viscosity and hematocrit (a calculation of the percent of red blood cells present in the blood) are measured. Alpha-thalassemia
Alpha-thalassemia, like sickle cell trait, is typically inherited in areas with increased exposure to malaria. It manifests itself as a decreased expression of alpha-globin chains, causing an imbalance and excess of beta-globin chains, and can occasionally result in anemic symptoms. The abnormal hemoglobin can cause the body to destroy red blood cells, essentially causing anemia.In endurance-trained individuals with sickle cell trait the presence of alpha-thalassemia has been shown to act protectively against microvasculatory distress before, during, and after exercise. Signs, symptoms, and prevention
Because of the microcirculatory distress, a telltale sign or symptom of a potential sickling collapse is cramping. Specifically to sickle cell trait, cramping occurs in the lower extremities and back in athletes undergoing intense physical activity or exertion. In comparison to heat cramps, sickling cramps are less intense in terms of pain and have a weakness and fatigue associated with them, as opposed to tightly contracted muscles that lock up during heat cramps.A sickling collapse comes on slowly, following cramps, weakness, general body aches and fatigue.