Is microalbuminuria a different problem for type I and type II diabetes mellitus?

As in previous studies an improved single radial immunodiffusion technique was used for albumin, calculating the albumin/creatinine ratio in spot urine (mg/g/1.73 m2). This ratio was 4.7 +/- 0.0174 (geometric mean +/- SEM as logarithm) in 130 healthy controls, the highest value being 10.8. The 182 non-selected ambulatory diabetic patients presented three subgroups, each showing a non-gaussian frequency distribution: 47% with normal values (5.0 +/- 0.0224); 42% with ratio values from 11.0 to 88.8 (22.7 +/- 0.0269, significantly differing from the controls); 11% with clinical proteinuria (subsequently excluded from the study). Type I (9.6 +/- 0.0452; n = 76) and type II diabetic patients (10.7 +/- 0.0430; n = 86) significantly differed (p less than 0.001) from the controls but not from one another. Irrespective of the diabetes type, ratio values were significantly correlated with the duration of diabetes, age of patients, age of diagnosis (for instance 16.2 +/- 0.0974 in 15 patients aged greater than 65 years versus 9.1 +/- 0.0792 in 23 patients aged less than 20 years), glycemia level and chronic complications (especially retinopathy). Therefore, more than half the diabetic patients, non-selected, presented an increased albumin excretion as compared to the controls. On the other hand, microalbuminuria appears to be linked to age, duration of the disease and quality of the metabolic control rather than to the diabetes type.

Albumin to creatinine ratios in early morning samples of urine from healthy persons and patients without clinical proteinuria.

Urinary excretion of albumin was determined in 133 clinically healthy subjects and 236 patients suffering from diabetes mellitus (150 cases), collagen diseases (45 cases), or arterial hypertension (41 cases) in whom there was no clinical or laboratory evidence of renal involvement. Urine albumin was measured by an improved single-radial-immunodiffusion technique and results were expressed as urine albumin to creatinine concentration ratio (mg/g). The geometric mean values in the patients were about 2 to 2.5 times higher than in controls. When considered on an individual basis, at least 40 per cent of the patients had values above the 99th-percentile value for controls. The results suggest that quantitative determination of urinary albumin may be useful for detecting early structural functional alterations of the glomerular filter.

An improved radial-immunodiffusion technique for measuring albumin in unconcentrated urine.

By exploiting the polymer-enhancing effect on the immunological precipitation, we have developed a highly sensitive, single radial-immunodiffusion (SRID) method for measuring albumin in urine. As little as 20 ng of albumin could be measured in a 4-microL sample of urine. Both within- and between-plate coefficients of variation were less than 5% over the range of albumin concentrations between 5 and 80 mg/L. Accuracy, as estimated from recovery studies, was also very good. The method is simple to perform and inexpensive (it requires only very small amounts of antiserum). The urinary albumin output, as determined on timed urine collections from 117 healthy persons (66 women and 51 men), ranged from 1.8 to 17.7 micrograms/min, with a geometric mean value of 6.8 micrograms/min (log SD = 0.1894). Based on the above-mentioned advantages of the method, we recommend it for routine use in clinical laboratories.

Urine proteins in renal disease. II. Alpha 2-microgiobulins in tubular proteinurias with special reference to endemic nephropathy.

Urine microglobulins were analyzed in 145 patients with a variety of chronic renal disease, 58 of whom had endemic nephropathy. On agarose-gel electrophoresis, the urinary-protein patterns of either tubular or mixed tubulo-glomerular type invariably showed two to three discrete alpha 2-migrating bands differing slightly in net charge. Marked differences in their relative concentrations occurred from one case to another and, following prolonged storage at 4 degrees C, in the same urine as well. All three fractions showed only a single precipitation line on immunoelectrophoresis when tested against antisera to urinary proteins; thus it would appear that they represent differently charged, but antigenically identical molecular forms of a protein of low molecular weight. The results also suggest that their detection might be used as an indicator for clinical purpose of impaired tubular function.

Influence of sex and age on serum immunoglobulin concentrations in healthy subjects.

Cencentrations of serum-immunoglobulins IG, IgA and IgM in 440 apparently healthy subjects aged 15 to 70 years were estimated by assay against the WHO International Reference Preparation 67/97. An improved single-radial-diffusion technique was used. Sex-related differences were separately examined for each age group by means of Stusdent's t test. Except for IgA mean value of the younger males (15--24 years), which was significantly (p less than 0.05) higher than that of females, no other significant sex differences were found for IgA mean levels; in contrast, mean IgM concentrations were significantly (p less than 0.001) higher in females than in males, in all but one (55--70 years) of the age groups. Linear-regression analyses of log10 Ig concentration on age have evidenced that a significant decrease in IgM levels with age occurred only in females (r = - 0.390; p less than 0.001); on the contrary, significant increases with age occurred in IgG concentrations of males (r = 0.271; p less than 0.001), as well as in IgA levels of both males (r = 0.240; p less than , less than 0.001) and females (r = 0.263 ; p less than 0.001).