Relationship between urinary albumin excretion rate and renal histology in non-insulin-dependent diabetes mellitus: with reference to the clinical significance of microalbuminuria

Urinary afamin levels are associated with the progression of diabetic nephropathy

AIMS

In this study, we applied quantitative proteomic analysis to identify urinary proteins associated with diabetic nephropathy (DN).

METHODS

Two-dimensional image-converted analysis of liquid chromatography and mass spectrometry detected the proteins differentially excreted between normoalbuminuric and macroalbuminuric patients with type 2 diabetes mellitus (T2DM) (n = 6 each). Urinary levels of excreted proteins were measured by multiple reaction monitoring (MRM) analysis using an independent sample set (n = 77). Urinary afamin levels were measured by ELISA in T2DM and DN patients enrolled in this cohort study (n = 203).

RESULTS

One-hundred-four proteins displayed significant alterations in excretion. Nine of these candidates were validated by MRM analysis. Among them, the levels of afamin, CD44 antigen, and lysosome-associated membrane glycoprotein 2, which have not previously been implicated in DN, were significantly associated with both the urinary albumin to creatinine ratio (ACR) and eGFR. We further measured afamin levels in urine collected from T2DM patients who did not yet have significant kidney disease (ACR < 300 mg/g or eGFR change rate ≤ 3.3%/year). The urinary afamin to creatinine ratio (Afa/Cre) was significantly higher in patients who progressed to a more severe DN stage or had early renal decline than in patients who did not.

CONCLUSIONS

Afa/Cre was significantly increased in T2DM patients who subsequently developed DN. Afa/Cre may be useful to predict patients with T2DM at high risk of nephropathy before the development of macroalbuminuria or reduced kidney function, although further validation studies in a larger population are needed.

Blunted erythropoietin response to anemia in patients with Type 1 diabetes

BACKGROUND

It is known that patients with renal failure have normochromic normocytic anemia due to impaired endogenous erythropoietin (EPO) synthesis. The aim of this work was to determine whether low serum erythropoietin (s-EPO) levels play a role in the pathogenesis of anemia in patients with Type 1 diabetes without overt nephropathy.

METHODS

We included in the study 13 patients with Type 1 diabetes whose Hb levels were <11 g/dl. Blood cell count, s-EPO, urinary albumin excretion rate (AER), HbA(1c), glomerular filtration rate, serum iron, serum ferritin, the presence of neuropathy, retinopathy and nephropathy were determined.

RESULTS

Ten out of 13 patients with anemia (77%) had a blunted EPO response to anemia. All ten patients with low EPO levels had autonomic neuropathy; five had clinical nephropathy but with serum creatinine<1.6 mg/dl. Three patients were treated with rHuEPO and showed an improvement in their anemia after treatment.

CONCLUSION

The majority of patients with Type 1 diabetes who had anemia also had low EPO levels. The pathogenesis of this phenomenon is probably multifactorial. Autonomic neuropathy appears to play a role, but it is not sufficient, per se, to be the only cause. Dysautonomia might enhance the effect of renal damage.

The association of microalbuminuria with diabetic retinopathy. The Wisconsin Epidemiologic Study of Diabetic Retinopathy

PURPOSE

To investigate the relationship between microalbuminuria and the presence and severity of diabetic retinopathy in a large population-based cohort of individuals with diabetes.

METHODS

Microalbuminuria was measured by an agglutination inhibition assay in random urine samples obtained from participants in the Wisconsin Epidemiologic Study of Diabetic Retinopathy (n = 1139) who did not have hematuria, gross proteinuria, or a history of renal disease. Retinopathy was determined from stereoscopic color fundus photographs graded according to a modification of the Airlie House Classification System.

RESULTS

Younger-onset (diagnosed with diabetes before 30 years of age) and older-onset (diagnosed with diabetes when 30 years of age or older) individuals with microalbuminuria were more likely to have retinopathy than those without microalbuminuria. Younger-onset individuals who had microalbuminuria at the time of examination were more likely to have proliferative retinopathy than younger-onset subjects with normoalbuminuria. These relationships remained after controlling for glycemia, hypertension, duration of diabetes, and other potential confounders.

CONCLUSIONS

Microalbuminuria is associated cross-sectionally with the presence of retinopathy in persons with diabetes and with the presence of proliferative disease in younger-onset individuals. These data suggest that microalbuminuria may be a marker for the risk of proliferative retinopathy developing. If longitudinal studies confirm these findings, individuals with insulin-dependent diabetes mellitus (IDDM) who have microalbuminuria may benefit from ophthalmologic follow-up.

Renal hypertrophy as a prognostic index for the progression of diabetic renal disease in non-insulin-dependent diabetes mellitus

The aim of this study is to elucidate the clinical significance of estimating renal size in non-insulin-dependent diabetes mellitus (NIDDM). Renal size was compared in 57 NIDDM patients with persistent normoalbuminuria [group I; 19 cases, albumin excretion rate (AER) < 20 micrograms/min], microalbuminuria (group II; 24 cases, AER = 20-200 micrograms/min), or macroalbuminuria (group III; 14 cases, AER > 200 micrograms/min). Three groups were matched for age and diabetes duration. Renal size was estimated using drip-infusion pyelography according to Simon's method (mean kidney length/height of second lumbar spine and disc; renal ratio, RR). Thirteen patients with persistent microalbuminuria (10 normotensive and 3 hypertensive) were traced during at least 3 years. Angiotensin-converting enzyme inhibitor (enalapril) was used in 11 cases. The results are as follows: (1) Renal size in groups II (RR, 3.47 +/- 0.28; cited as mean +/- SD) and III (3.62 +/- 0.32) significantly increased compared with that in group I (3.26 +/- 0.20) (p < 0.01 and p < 0.001, respectively). No statistical differences could be detected between groups II and III. (2) As a whole, good metabolic (glycosylated hemoglobin, HbA1) and hemodynamic (systolic blood pressure, SBP) control was achieved during the last 12 months (HbA1, 8.4% +/- 0.9%; SBP, 122 +/- 8 mm Hg). There was no significant correlation between RR and creatinine clearance, HbA1, SBP, or diastolic blood pressure during the first and last 12 months. Initial RR significantly correlated with AER during the last 12 months (r = 0.651, p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)