case study by Azin Mashayekhi , MD , MBA 1 ; Justin Bean 1 ; Hoda Hagrass , MD , PhD 1
A Patient Without Hemoglobin A1c
1
Department of Pathology , UAMS , Little Rock , Ark .
Abstract
Diabetes prevalence is high . International diabetes federation determined that 463 million adults live with diabetes ( 2019 ), and the projected number will increase to 578 million by 2030 .
Glycated hemoglobin is routinely measured in the clinical laboratory to diagnose and monitor diabetes mellitus . The hemoglobin ( Hb ) variants can affect the HbA1c measurement ' s accuracy either through analytical interferences or by influencing the HbA1c result ' s interpretation by changing RBC lifespan . The most prevalent types are HbS , HbC , HbD , and HbE . In a patient with HbE , HbA1c may not be detectable by ion-exchange chromatography but may be measured by immunoassay technique .
Table 1 . Patient ’ s laboratory test results
Lab test Value ( reference interval )
CBC RBC Hb Hct MCV MCHC RDW WBC PLT
Case Presentation
A 77-year-old male was presented with painful left-foot ulceration with surrounding cellulitis , after a fall and foot fracture sustained about two months previously . The patient had a history of diabetes type 2 and was scheduled for below-knee amputation . The orthopedic team ordered CBC , BMP , C-reactive protein ( CRP ), Hb A1C , and troponin as pre-procedure screening ( Table 1 ).
For Hb A1C , we use HPLC technology D-100 cationic liquid chromatography ( Bio-Rad Clinical Diagnostic Solutions ); a flag “ No Hb A1C peak ” was shown ( Figure 1 ). We sent the specimen to our sister pediatric hospital for HbA1c by immunoassay on Vitros 5600 Ortho Clinical Diagnostics . The result using this method was 5.8 %. Based on the HbA1c result flag and the immunoassay ’ s result , we reached out to the clinical team and advised them
5.08 M /µ L ( 4.50 - 5.70 M /µ L ) 10.2 g / dl ( 13.0 - 17.0 g / dL ) 30.5 %( 40.0 - 50.0 %) 60 fl ( 80.0 - 100.0 fL ) 33.4 g / dl ( 32.0 - 36.0 g / dL ) 17 % ( 12.0 - 15.0 %) 16.48 K /µ l ( 3.60 - 9.50 K /µ L ) 219,000 K /µ L ( 150 - 450 K /µ L )
K 3.2 mmol / L ( 3.5 - 5.1 mmol / L ) Ca 8.0 mmol / L ( 8.6 - 10.2 mg / dL ) BUN 35 mg / dl ( 6 - 20 mg / dL ) Creatinine 1.9 mg / dl ( 0.6 - 1.3 mg / dL ) ESR 97 mm / hr ( 0 - 20 mm / hr ) CRP 50.90 mg / L (<= 10.00 mg / L ) Plasma glucose 110 md / dl ( 70 - 110 mg / dL ) to order either glycated albumin or fructosamine to confirm the glycemic control . The result for fructosamine reported by our reference laboratory was within the reference interval of 200-285 µ mol / L ( i . e ., fructosamine = 266 µ mol / L ). The fructosamine was measured using colorimetric assay ( absorbance is measured photometrically at 546 nm ), which depends on its ability to reduce nitroblue tetrazolium to formazan in an alkaline solution ( Package insert : Roche Fructosamine reagent , Roche Diagnostics Corp ., Indianapolis , IN 1999 ).
We observed a prominent peak in the E window after reviewing the HbA1c chromatogram ( Figure 1 ). We reanalyzed the specimen using the D-10 extended ( HbP ) program . A peak of 85.6 % in the A2 area was found . According to our procedure , as hemoglobin D and E have been observed to co-elute with HbA2 , we sent the specimen to our reference laboratory for confirmation by a different methodology ; electrophoresis cascade . The patient is confirmed to have HbE ( 93.0 %) ( Table 2 ).
Discussion
The glycated hemoglobin ( HbA1c ) has been proved as a gold standard biomarker for long-term glycemic control and can also be used to diagnose diabetes . Highly precise and accurate HbA1c assays , under supervision of the National Glycohemoglobin Standardization Program ( NGSP ) certification , allow clinicians to monitor diabetic patients , make treatment modifications , and analyze outcomes . 1 HbA1c concentration depends on the erythrocyte ( RBC ) lifespan and is related to the glucose concentration over the last 90-120 days . Due to the dynamic balance of the formation , breakdown , and removal of RBC together with their HbA1c molecules as the old RBC cohort leaves the circulation ; the HbA1c is more
177 • The Journal of the Arkansas Medical Society www . ArkMed . org