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Urinary protein excretion and renal function in young people with diabetes mellitus
1Department of Renal Medicine, Karolinska Institute, Huddinge University Hospital, Sweden.
Insights
Early diabetic kidney disease in youth involves both glomerular and tubular damage. Hyperfiltration declines with increased albuminuria and longer diabetes duration, indicating progressive renal dysfunction.
Area of Science:
- Nephrology
- Endocrinology
- Pediatrics
Background:
- Diabetic nephropathy is a major complication of type 1 diabetes.
- Early detection of renal involvement in young patients with insulin-dependent diabetes mellitus (IDDM) is crucial.
- Urinary protein excretion and renal function markers are key indicators of kidney health.
Purpose of the Study:
- To investigate early renal involvement in young patients with IDDM.
- To assess the relationship between urinary protein excretion, renal function, and diabetes duration.
- To determine the origin (glomerular vs. tubular) of early albuminuria in diabetic youth.
Main Methods:
- Studied 110 young IDDM patients (aged 5.9-25.0 years).
- Measured inulin and PAH clearances, and urinary excretion rates of albumin (Alb), IgG, N-acetyl-beta-D-glucosaminidase (NAG), and creatinine (Cr).
- Grouped patients by IDDM duration and albumin excretion rate (non-albuminuria, microalbuminuria, albuminuria).
Main Results:
- Increased glomerular filtration rate (GFR) observed in non-albuminuric patients; GFR normalized in micro/albuminuric patients.
- Longer IDDM duration (>10 years) correlated with lower GFR in non-albuminuric patients.
- Shorter IDDM duration (<5 years) with micro/albuminuria was associated with reduced GFR.
- Elevated NAG excretion linked to altered sodium and creatinine excretion.
- Albumin excretion correlated with IgG and NAG excretion, suggesting combined glomerular and tubular dysfunction.
Conclusions:
- Early albuminuria in IDDM appears to originate from both glomerular and tubular damage.
- Hyperfiltration decreases as albuminuria increases and with longer diabetes duration.
- These findings highlight the complex, progressive nature of diabetic kidney disease in young individuals.
Abstract:
To detect early renal involvement in young diabetic patients (IDDM), urinary protein excretion and renal function were examined in 110 patients aged 5.9-25.0 years. Clearances of inulin and PAH were determined as well as albumin (Alb), IgG, N-acetyl-beta-D-glucosaminidase (NAG) and creatinine (Cr) excretion rates (UV). The patients were grouped according to IDDM duration (2- less than 5, 5-10 and greater than 10 years) and albumin excretion rate (non-albuminuria less than 20, microalbuminuria 20-200, and albuminuria greater than 200 micrograms/min per 1.73 m2). Four patients had overt albuminuria, 17 microalbuminuria (equally distributed among the duration groups). Grouped according to albumin excretion rate, the mean GFR was increased in those without albuminuria but 'normalized' in patients with microalbuminuria/albuminuria. Grouped according to albumin excretion rate and the duration of the disease, the non-albuminuric patients with IDDM for greater than 10 years had a lower GFR than those with a shorter duration of IDDM. The patients with microalbuminuria/albuminuria and IDDM for less than 5 years had a reduced GFR. Patients with increased NAG excretion rate had lower Na excretion rate, lower fractional Na excretion and greater creatinine excretion than those with normal NAG excretion. Albumin excretion correlated with IgG excretion, but also with NAG excretion. Our results suggest that early albuminuria in IDDM is of both glomerular and tubular origin. The hyperfiltration declines with increasing albumin excretion but also with the duration of the disease.