Laboratory diagnosis of renal failure: urine conductivity and tubular function.

AIM: Conductivity is a measure of a material's ability to conduct an electric current and it works thanks to movable charges. Conductivity in urine is directly proportional to ionic contents. The aim of this study was to evaluate the significance of urine conductivity by using the Sismex UF-100 analyser in correlations with other surrogate parameters of osmolality and renal diuresis, relative density, electrolytes and creatinine concentration. METHODS: For this study 140 urine samples were submitted for diagnostic urinalysis to the Clinical Pathology laboratory. Samples were collected from 70 healthy subjects, 42 diabetics with poor metabolic control and significant glicosuria, 28 patients with monoclonal gammopathy of uncertain significance, with significant proteinuria. All the samples were assessed for conductivity (UF-100 Sysmex), relative density (refract meter Zeiss), sodium, potassium, chlorine, creatinine, urea, glucose, protein (Olympus AU-2700). RESULTS: Urine conductivity appears to be related to ionic concentration but not to glucose and/or protein presence. CONCLUSIONS: This study results suggest that conductivity determination should be useful in diabetic patients to study the tubular function minimising interferences due to osmotic action of glucose.

Blood viscosity studies in native and reconstituted polycythemic blood.

In twelve subjects with Polycythemia vera (P.V.) whole blood, plasma and relative viscosities and the main factors capable of influencing such parameters (Hct, RBCs, WBCs and platelet count, total proteins, gamma-globulins and fibrinogen) were investigated. Ten normal subjects of similar age and sex were studied as control. Whole blood viscosity was determined both in basal conditions and after reconstitution of Hct to normal values by adding some autologous plasma. After the reconstitution of Hct the subjects studied were divided into two groups on the basis of the correlation between Hct and whole blood viscosity. The first group (group A) had a good correlation between Hct and whole blood viscosity; on the other hand the second group (group B) did not show any significant correlation between these two parameters after reconstitution. In basal conditions none of the parameters capable of influencing whole blood viscosity or plasma viscosity permitted any discrimination between the two groups. The relative viscosity, which represents an indirect index of red blood cell deformability, appears to be more elevated in group B. Therefore, the different behaviour of polycythemic blood after reconstitution of Hct might be conceived to be due to a difference in red cell deformability.

Clotting changes in Cushing's syndrome: elevated factor VIII activity.

Thirteen women and 2 men affected by Cushing's syndrome were investigated. The following parameters were used: plasma and urinary cortisol levels, factor VIII assay (antigen, activity and von Willebrand factor) together with other coagulative assays. Samples were taken before surgery or before medical and/or radiation therapy and every 30-50 days after treatment and continued for 11 months. Cortisol and factor VIII were increased before treatment and decreased slowly after treatment to become normal in 3-4 months. Other clotting tests did not show any significant changes. High plasma cortisol levels seem to stimulate the production of factor VIII. Patients with Cushing's syndrome often exhibit thromboembolic complications after surgery. The clotting abnormalities responsible for such complications may be due to increased factor VIII activities.

Increased factor VIII associated activities in Cushing's syndrome: a probable hypercoagulable state.

Thirteen women and 2 men affected by Cushing's syndrome were investigated. The following parameters were used: plasma and urinary cortisol levels, factor VIII assay (antigen, activity and von Willebrand factor) together with other coagulative assays. Samples were taken before surgery or before medical and/or radiation therapy and every 30-50 days after treatment and continued for 11 months. Cortisol and factor VIII were increased before treatment and decreased slowly after treatment to become normal in 3-4 months. Other clotting tests did not show significant changes. It seems that high plasma cortisol levels may stimulate the production of factor VIII. Patients with Cushing's syndrome often exhibit thromboembolic complications after surgery. It is likely that the clotting abnormalities responsible for such complications is the increased factor VIII activities level.