Protein‐loading test, urinary albumin excretion and renal morphology in diagnosis of subclinical diabetic nephropathy

Abstract

The acute effects of protein loading (1.5 g kg-1) on glomerular filtration rate (GFR) and urinary albumin excretion (UAE) were investigated in 23 type-I diabetic patients with no clinical nephropathy, and in 7 healthy subjects (controls). The results were compared with renal morphology data. In controls and in 14 diabetic patients (group 1) GFR increased by 27 and 37%, respectively, corresponding to normal renal reserve, but in 9 patients (group 2) GFR decreased by 20%, indicating the absence of a renal reserve. Microalbuminuria was found in none of the patients in group 1 and in 50% of patients in group 2. Two hours after the load UAE increased in all groups, but the increase was most marked in group 2, despite the fall in GFR. The two groups of patients did not differ with regard to the duration and control of diabetes, but differed markedly in terms of baseline GFR (131 vs. 195 ml min-1, P less than 0.01, in groups 1 and 2, respectively). Renal morphology showed minimal non-specific glomerular injury in group 1, and signs of glomerulosclerosis in group 2. We conclude that the impaired renal response to protein load precedes other subclinical manifestations of diabetic renal injury, and may be useful in the diagnosis of latent diabetic nephropathy.

Renal Functional Reserve in Patients with Recently Diagnosed Type 2 Diabetes mellitus with and without Microalbuminuria

“…If lost, maximal GFR is established [18]. FRR is lost at early phases of type 1 DM [19]. At that stage the FRR and its relationship with urinary protein excretion and metabolic control are unknown.…”

Dissociation of Blood Pressure and Albuminuria in Normal Subjects Infused With Angiotensin Ii and Noradrenaline

“…This time point was prior to commencement of infusions and the finding is of considerable interest. Many factors other than BP have been associated with acute elevation in AER, including dietary protein (Shestakova et al 1992), posture, exercise (Gatling et al 1985 and diuresis (Viberti et al 1982). There was no relationship between urine volume and AER (Fig.…”

Renal functional reserve in patients with Type 1 diabetes mellitus

“…In the literature there is considerable inconsistency in reported RFR values in patients with Type 1 diabetes. In two studies where kidney biopsies were performed, negative RFR was found in patients with histological signs of glomerulosclerosis [1] and in patients with hilar glomerular lesions with expanded mesangium [2]. In both studies it was suggested that negative RFR precedes other subclinical manifestations of diabetic nephropathy.…”

“…Some patients with Type 1 diabetes mellitus have decreased renal functional reserve (RFR) before they develop incipient diabetic nephropathy [1,2] as characterised by microalbuminuria. At a very early stage of diabetic nephropathy, reduced endothelial sensitivity of renal afferent arterioles to nitric oxide occurs [3], possibly caused by reactive oxygen species [4,5].…”