From “BJ:” I recently cared for a 60 yr old type 2 diabetic in hyperglycemic hyperosmolar state. Initial serum glucose 960. The partial thromboplastin time (PTT) was initially 78 seconds without clear reason. The international normalized ratio (INR) was 1.4. The prothrombin time (PT) was not initially checked. I felt that the value was likely spurious and I repeated the test a few hours later, with normal result. At that time blood glucose had improved to within the 300s with fluids and insulin. Are you aware of a mechanism whereby severe hyperglycemia can cause the PT/PTT to result artifactually high?
Hello, and thank you. Yes, I agree that the prolonged PT and PTT were artifacts. You don’t mention ketoacidosis, but I’m assuming an acid pH in addition to the raised osmolality, which together would reduce the normal function of coagulation enzymes. Your question drove me to PubMed, where I found no publication to support this conclusion, so we’ll have to agree it is a “scientific wild guess” based on our understanding of physiology.
Mar 31 2014
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Screening Assays
Several earlier publications (based on in vitro studies) sug
Several earlier publications (based on in vitro studies) suggested that a high plasma glucose level might affect fibrinogen polymerization leading to TT, APTT and PT prolongation:
“…hypertonic glucose caused a significant prolongation in TT at only 5% volume replacement. Since TT is a measure for functional fibrinogen, the effect of glucose on TT indicates therefore that the latter impair the clot-forming ability of fibrinogen. This is in agreement with Einerson, who demonstrated that addition of 3% glucose to fibrinogen causes a profound decrease in the amount of clottable protein and a prolongation in the thrombin clotting time…”
also from:
Wilder DM et al. Hypertonic resuscitation and blood coagulation: in vitro comparison of several hypertonic solutions for their action on platelets and plasma coagulation. Thromb Res. 2002 Sep 1;107(5):255-61.
Einerson R. The clot-forming ability of fibrinogen in solutions containing glucose and sorbitol. Thromb Res. 1975;7:9258.