An early diagnosis of kidney involvement in immunologically-mediated multisystem diseases.

Kidney involvement in immuno-mediated diseases is a life threatening complication to be early detected. Glomerulo-tubular functional indices, kidney-released enzymes and metabolic profiles were assessed in 21 patients with systemic lupus erythematosus, progressive systemic sclerosis and mixed cryoglobulinaemia, without overt nephropathy at a current laboratory examination, and in 31 age-sex-matched healthy controls. All patients had a urinary total protein excretion rate higher than controls (353.6 +/- 182.4 vs 243.0 +/- 108.2 mg/24 h, p < 0.01); 12 of them resulted albuminuric (775.5 +/- 1192.4 mg/24 h), while 9 were normoalbuminuric (16.6 +/- 7.6 mg/24 h). Urinary enzyme excretion rates (GGT and NAG) were significantly heightened compared to healthy subjects, both in albuminuric and in normoalbuminuric patients. Serum albumin resulted significantly lower in all patients, independent of their urinary albumin leakage. Finally, all subjects with connective tissue diseases had significantly higher triglycerides, lower HDL cholesterol and double serum fasting insulin than normals. In conclusion, all patients with collagen diseases show signs of subclinical nephropathy, not always detectable by albuminuria. They also provide evidence of insulin-resistance, a conceivable forerunner of cardiovascular complications.