Postrenal acute kidney injury is caused by an acute obstruction that affects the normal flow of urine out of both kidneys. Urinary tract obstruction increases intratubular pressure and thus decreases glomerular filtration rate.

Material and methods:

 We report a case of neurogenic bladder in patient with Down syndrome complicated by a postrenal increase in the serum creatinine level and megaureter.

Results:

 The 10 years old boy with Down syndrome lives in the family for the last two years. Prior to that, he was in the orphanage and there were no reports about kidney anomalies or urination problems. In October 2017, the parents went to the Emergency Department complaining of the periorbital puffiness of the child, as well as the absence of urination. On US examination - marked dilatation of the urinary tract, the volume of the bladder - more than 500 ml. In laboratory tests: creatinine - 985 µmol/l (11.5 mg/dl), GFR (reversed Schwartz) - 5.2 ml/min, urea – 50,2 mmol/l. When the urethral catheter was staged, 700 ml of urine was excreted simultaneously. A permanent (Foley) catheter is left for the duration of treatment. The rapid decrease in azotemia was noted in the assays: a day later - creatinine 396 μmol /l (4.5 mmol/l), urea – 35 mmol/l, in a week - 95 μmol /l (1.07 mmol/l) and 14 mmol/l respectively, after 16 days – 75 μmol /l (0.85 mmol/l) and 6.8 mmol/l. No dilatation of urinary tract on US, no VUR or urethral obstruction on MCUG. Clean intermittent catheterization and correct water load was recommended. In 6 months –  creatinine - 60 μmol /l (0.68 mmol/l), GFR (reversed Schwartz) - 85 ml/min, no urinary tract dilatation.

Conclusions:

 Prompt diagnosis of postrenal acute kidney injury followed by early relief of obstruction is associated with improvement in renal function.