Two panels, one deteriorating patient

An adult inpatient with a documented severe systemic inflammatory illness has coagulation studies drawn at 07:30 and again at 13:30 from a newly drawn, fully filled citrate specimen. The platelet count falls from 112 to 44 x10^9/L. PT rises from 15.2 to 19.0 seconds and aPTT from 34 to 48 seconds, both above the local adult reference interval. Clauss fibrinogen falls from 310 to 165 mg/dL, moving from normal to low against a 200-400 mg/dL interval. Quantitative D-dimer rises from 1,400 to 4,500 ng/mL fibrinogen-equivalent units (FEU) against a local upper limit of normal of 500 ng/mL FEU. Creatinine rises from 1.0 to 1.6 mg/dL, and the 13:30 smear now shows rare schistocytes with a platelet estimate concordant with the automated count.

None of these seven results is, by itself, a diagnosis. A single low platelet count could reflect a clotted or partially clotted specimen, a dilutional effect from fluid resuscitation, an unrelated marrow process, or early consumption. A single elevated D-dimer is common and nonspecific. What makes this pair of panels worth stopping on is that six analytes moved together over six hours, in a direction that is coherent with one process: platelets and fibrinogen both falling while PT, aPTT, D-dimer, and creatinine all rise.

This is not about whether the patient has DIC. It is about what several coagulation results deteriorating together actually mean: what process pattern is supported by the evidence in front of you, and what alternative explanations remain open until more information arrives. A laboratory scientist answers that question from trends, specimen integrity, and method limitations, not from a label alone.

Before reacting to any one abnormal value, pull the prior result and ask whether the direction of change, not just the current flag, is consistent across the panel.