Fifty‐five patients with clinical signs of acute DVT were investigated with thermography, plethysmography and phlebography. A comparison between phlebography and thermography showed a diagnostic agreement of 84%. Thermography was found, however, to have a low reliability for the localization of acute thrombi and was therefore combined with plethysmography in an attempt to obtain better results in this respect. Compared to the invasive phlebography, the noninvasive combination of thermography and plethysmography adequately located acute DVT in 95% of the cases.

Plasma levels of platelet factor 4 (PF4) determined in 58 apparently healthy subjects were found to increase with age. In 66 insulin dependent diabetics, PF4 plasma levels were increased but unrelated to the age of subject. Mean fibrinopeptide A levels were elevated in the diabetics but not correlated to PF4 levels. Activation of the coagulation system with thrombin generation thus seems to be operative in diabetes, but the enhanced platelet activation also observed in this disease is probably not thrombin mediated. No correlation was found between PF4 plasma concentration and the degree of vascular complication, HbA1c, blood glucose, 24‐h urinary glucose, serum cholesterol or serum triglycerides.

Plasma levels of platelet factor 4 (PF 4) were determined in 30 patients with recent acute myocardial infarction. Comparisons were made with the levels in 26 age-matched controls. In another 15 patients, also with recent myocardial infarction, PF 4 plasma levels were determined before and immediately after a standardized exercise stress test. At rest, none of the patients had elevated PF 4 levels. Only one patient demonstrated an increase after exercise. These fmdings are in conflict with some recent reports. The importance of age-matched controls, the hazard of in vitro platelet activation and the possible effect of &blocking and calcium-antagonistic drugs on PF 4 plasma levels is discussed below.