[Early diagnosis of impaired glomerular and renal tubule function in patients with acromegaly].

BACKGROUND

Albuminuria (A), increased urinary excretion of glycosaminoglycans (GAG) and increased activity of N-acetyl-beta-glucosaminidase (NAG) in urine are early markers of glomerular and tubular changes in various pathological conditions at a time when renal functions do not yet display impaired function and when the changes are still reversible. The objective of the presented study was to assess to what extent these early changes may play a part in acromegaly.

METHODS AND RESULTS

In a group of 24 acromegalic patients and in 18 healthy controls the authors examined the microalbuminuria (RIA Immunotech Prague), urinary excretion of glycosaminoglycans (spectrophotometrically by the carbazole method) and they assessed the NAG activity in urine (spectrophotometrically). In acromegalic patients before surgical and pharmacological treatment the authors found, as compared with healthy controls, increased urinary excretion of GAG [4.4 (0.9-22.7) g/mol creat. vs. 2.1 (0.8-5.5) g/mol creat, p < or = 0.001], elevated albuminuria [3.6 (0.3-37.4) g/mol creat. vs. 0.5 (0.1-2.2) g/mol creat, p < or = 0.001 and an enhanced NAG activity [1005 (345-2935) U/l vs. 470 (195-1135) U/l, p < or = 0.001]. The parameters of albuminuria and urinary GAG excretion characterize rather glomerular renal function, they correlate mutually (r = 0.64 p < or = 0.001), while the urinary NAG activity, depending on tubular function, does not correlate with them. No correlation of these parameters with the IGI concentration (for A: 0.3, for GAG: -0.04 and for NAG: -0.02 according to Pearson was found.

CONCLUSIONS

In hormonally active acromegalic patients without apparent altered renal functions (normal serum creatinine, Albustix negative) the authors detected early changes of glomerular and tubular functions. They found a significant correction between albuminuria and GAG excretion.