Causes
Pseudohypoglycemia or artifactual hypoglycemia can occur in the following situations:
- Decreased capillary flow resulting in decreased glucose transport through the tissues and increased tissue extraction of glucose.[5] It can occur in:
- Raynaud phenomena [6, 7]
- Acrocyanosis[8]
- Peripheral vascular disease
- Eisenmenger syndrome [9]
- Circulatory shock
- Increased glycolysis by the leucocytes and red blood cells when there is a delay in interpreting the blood sample or separating plasma from the blood sample. Even in patients with normal leucocyte counts an artificial decrease in glucose level (0.17 mmol/L/h) is seen when it is allowed to clot at room temperature.[10] Serum glucose concentration starts falling precipitously within 2 hours of collection if not refrigerated.[11] A 90% lowering of glucose levels occurred when the blood was kept at room temperature for 2 hours. That can happen with:
- Leukemia[12, 13, 14]
- Leukemoid reactions including eosinophilic leukemoid reaction due to underlying poorly differentiated carcinoma and hematopoietic cytokines-stimulated leukocytosis.[10]
- Polycythemia vera [15, 11]
- The same findings have also been observed in blood samples containing high levels of other cell types due to the above mechanism as in chronic hemolytic anemia.[16, 17] Primary red cell disorders associated with decreased survival and reticulocytosis can also alter glycohemoglobin measurements making them appear low.[17]
- African trypanosomiasis causes in vitro use of glucose.[18]
- Hyperviscosity syndromes can cause artifactual hypoglycemia as well, as observed in:
- Waldenstrom macroglobulinemia [19, 20]
- Monoclonal gammaglobulinemia of undetermined significance (MGUS)[21]
- This is no longer observed after the plasmapheresis or appropriate dilution of the sample to a serum viscosity of 1.4-1.8, as measured with a capillary Ostwald viscometer.[19, 21, 20]
- Hypertriglyceridemia[22]
- Effect of various drugs on interpretation of glucose by different glucose meters.[23] Although there is a dose response relationship with the drug level and glucose interpretation, this is confounded by various factors especially in critically ill patients due to associated liver or kidney dysfunction which may raise the level of the drugs even when given at a therapeutic dose. It becomes clinically important to monitor these patients closely. Drugs causing that problem include:
- Ascorbic acid (especially high doses used in cancer therapy)[24]
- Dopamine
- Acetaminophen
- Mannitol
- In hospital settings, various other factors should be taken into consideration which may affect the glucose meter readings.
Severe acidosis (pH <6.95) can falsely decrease glucose readings[22]
Patients receiving high flow oxygen can have false low readings with glucose meter using glucose oxidase method[22]
High hematocrit as in neonates can also cause false low blood glucose readings.[25]