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Utility of filtration markers to monitor the quality of glomerular function
1Servicio de Análisis Clínicos, Hospital Universitario de Valme, Spain.
Abstract:
Diabetes mellitus can lead, along the years of its course, to chronic renal failure in a high proportion of cases. An early risk-indicator of later diabetic nephropathy is the presence of microalbuminuria, but it usually takes about fifteen to twenty years to appear. Before that, no clinical signs can disclose the underlying alterations of glomerular basement membrane that will eventually bring forth overt nephropathy. The usefulness of the altered excretion of isoenzymes of amylase as an early marker of the glomerular charge selectivity was tested in 202 juvenile onset insulin-dependent diabetics, compared with 51 normal subjects matched for age and sex. The diabetic patients studied showed increased excretion of salivary amylase into urine. The salivary to pancreatic amylase ratio of concentrations in urine was always below 1 in normal subjects, and was increased over 1 in 33.2% of diabetics, although microalbuminuria was present only in 26.2% of patients. The excretion of other proteins was within reference values in the majority of cases, indicating that the kidney was not seriously affected in those patients. Moreover, the altered salivary to pancreatic amylase ratio in urine was more prevalent than microalbuminuria (36.6% vs 18%) in the first decade of the evolution of the diabetes. These results indicate that the ratio of excretions of both isoamylases into urine is a more sensible and earlier marker of altered glomerular charge barrier for anionic proteins.
Insights
Diabetic nephropathy detection can be improved. A study found that the ratio of salivary to pancreatic amylase in urine is an earlier indicator of kidney damage in diabetics than microalbuminuria.
Area of Science:
- Nephrology
- Diabetology
- Biochemistry
Background:
- Diabetic nephropathy is a common complication of diabetes mellitus, often leading to chronic renal failure.
- Microalbuminuria is a known early indicator of diabetic nephropathy, but typically appears 15-20 years after diabetes onset.
- Early detection of glomerular changes before overt nephropathy is crucial for timely intervention.
Purpose of the Study:
- To investigate the utility of urinary isoenzyme excretion as an early marker for altered glomerular charge selectivity in diabetic patients.
- To compare the prevalence of altered amylase isoenzyme ratios with microalbuminuria in early-stage diabetes.
Main Methods:
- Assessed urinary isoenzyme excretion of salivary and pancreatic amylase in 202 juvenile onset insulin-dependent diabetics and 51 healthy controls.
- Calculated the ratio of salivary to pancreatic amylase concentrations in urine.
- Compared these ratios with the presence of microalbuminuria and other urinary protein levels.
Main Results:
- Diabetic patients exhibited increased urinary excretion of salivary amylase.
- The salivary to pancreatic amylase ratio was elevated (over 1) in 33.2% of diabetics, compared to normal subjects.
- Altered amylase ratios were more prevalent than microalbuminuria, especially within the first decade of diabetes (36.6% vs 18%).
- Other urinary protein excretions were largely within normal limits, suggesting preserved overall kidney function in many patients.
Conclusions:
- The ratio of urinary salivary to pancreatic amylase isoenzymes serves as a more sensitive and earlier marker of altered glomerular charge barrier for anionic proteins than microalbuminuria.
- This finding offers a potential new tool for the early detection of diabetic nephropathy, enabling earlier therapeutic interventions.