Serum erythrocyte folate levels in thalassaemic patients in Thailand.

The mean serum and adjusted red cell folate levels, as measured by microassay using Lactobacillus casei, respectively were 8.87 +/- SD 3.28 microgram/l and 436 +/- SD 107 microgram/l in 76 normal subjects, 4.22 +/- SD 2.70 microgram/l and 182 +/- SD 114 microgram/l in 55 patients with beta-thalassaemia/Hb E disease and 6.36 +/- SD 2.95 microgram/l and 320 +/- 158 microgram/l in 37 patients with Hb H disease. The mean serum and adjusted red cell folate values of the patients with beta-thalassaemia/Hb E disease and the mean serum folate value of the patients with Hb H disease were significantly lower than those of the normal subjects (P less than 0.001). 33% of the beta-thalassaemia/Hb E patients and 8% of the Hb H patients showed low serum folate levels (less than 3 microgram/l) whereas 84% of the former and 45% of the latter showed low adjusted red cell folate levels (less than 270 microgram/l). The group of beta-thalassaemia/Hb E disease with low serum folate levels had lower mean haemoglobin concentration and lower mean adjusted red cell folate level than the group with normal serum folate levels. Since the Thai diets have high folate content, the observed low serum and erythrocyte folate levels in thalassaemic patients most likely occur from massively increased erythropoiesis. Folate, 5 mg/d, is now routinely prescribed to such patients especially to those with severe anaemia.