Summary
14 patients (5 diabetics with arteriosclerotic complications, 4 patients with thrombo-embolic
disease, 4 with cirrhosis, coagulation defects and increased fibrinolytic activity,
and 1 cancer patient) and 3 control patients were subjected to turnover studies with
13iodine labelled human fibrinogen.
Half-life times in the control patients were found to be 4 days, the fractional turnover
rates 19–23 per cent, of intravascular fibrinogen per day, and the absolute turnover
0.02 to 0.06 gm per day per kg. body weight. The other patient’s half-life times and
turnover rates varied considerably from 0.9–5.5 days, 13–160 per cent, per day of
intravascular fibrinogen and 0.02–0.4 gm per day per kg. body weight respectively.
As fibrinogen unlike other proteins subjected to turnover studies, is converted to
fibrin, it is not possible to measure the true intra-extravascular distribution ratio
of fibrinogen. But intravascular fibrinogen could be approximated to constitute 68–99
per cent, of the total fibrinogen. There is justification in believing that fibrinogen
is degradated through a continuous coagulation in equilibrium with fibrinolysis, and
that the organism contains a greater mass of fibrin, the “fibrin pool”. Considerations
of the turnover mechanism can however only be hypothetical.
