Normal Levels of Folate in Serum, Red Blood Cell and Whole Blood in the Northeast of Thailand: Microbiological Technique - ค่าปรกติของระดับโฟเลตในซีรัม เม็ดเลือดแดงและเลือดรวมในคนไทยภาคตะวันออกเฉียงเหนือ กรณีศึกษาเทคนิค Microbiological assay

Abstract

           The function of folate or folic acid was mainly in human metabolism. Folate deficiency leads to impaired cell division manifested as megaloblastic anemia and foetal development neural tube defect. Moreover, it has also been linked to elevated levels of serum homocysteine, a condition implicated as an independent risk factor for coronary artery discase and stroke.

           Six hundred of blood samples were collected from healthy subjects attending Subpasitthiprasong Hospital Ubon Ratchathani province, Amnatchareon Hospital and Khon Kaen Hospital. Levels of folate present in serum, red blood cell and whole blood were assayed microbiologically using chloramphenicol resistant, Lactobacillus rhamnosus (ATCC 27773) that was previously known as Lactobacillus casei subsp. rhamnosus, as the test organism. Folate was used in their growth and the growth rate was detected from turbidity of medium by a spectrophotometer; the readings of folate concentrations were derived from a standard curve. The results revealed that the ranges of serum, red blood cell and whole blood folate were 5.7-42.7, 402.36-1,160.24 and 118-502 nmol/L, respectively. Their distributions appeared normal. As such, ± 2 SD had been used to calculate the normal levels of folate in serum of 5.12 - 40.48 nmol/L, red blood cell of 445.28 - 1,065.84 nmol/L and whole blood of 189.91-454.87 nmol/L. The cut-off points are less than 5.28 nmol/L in serum, 290.14 nmol/L in red cell and 123.67 nmol/L in whole blood. It could be concluded that the detection of folate level by this method has good precision, accuracy and sensitivity. Moreover, the method is relatively, less expensive and simple.