Introduction: Diabetes mellitus (DM) and hypertension are the most frequent causes of kidney function damage. Many different tests are developed to detect reversible functional kidney changes (detection of microalbuminuria and selective urinary enzymes).
Objective: The aim of our study was to examine tubular kidney function in type 2 DM patients with different proteinuria levels, and to compare these results with healthy people.
Method: The patients with type 2 DM and creatinine clearance >80 ml/min were included in the study. According to the levels of proteinuria, the patients were classified in three groups: group I--patients with proteinuria <300 mg/24 h, and no microalbuminuria; group II--the patients with proteinuria <300 mg/24 h and microalbuminuria >20 mg/24 h; and group III--the patients with proteinuria >300 mg/24 h. The control group consisted of healthy subjects.
Results: The study revealed that in type 2 DM patients and normal global kidney function, fractional excretions of sodium, potassium, and phosphates as well as renal phosphate concentrations were not adequately sensitive markers to detect damage in tubular kidney function in DM. There were some changes of urate fractional excretion in these patients: this value was significantly lower in patients with microalbuminuria compared with those with proteinuria >300 mg/24 h, as well as in the control group (p < 0.05). Hormone dependent tubular kidney activity, urinary osmolarity, and urea fractional excretion in all patients were within normal ranges.
Conclusion: It is evident that routine laboratory analyses are not sensitive markers to detect early changes of kidney function in type 2 DM.