342 thrombosis and hypertension, the latter perhaps exacerbated by reduction in hypoxic vasodilatation. Experience in adults [1 5] has shown that both these adverse effects are indeed seen. The assessment of hypertension is particularly difficult in this population as the underlying renal disease is itself a major aetiological factor. The need for a third of the previously hypertensive children to increase their medication, together with the need for first-time anti-hypertensive medication in a further 4 children during the first 16 weeks o f treatment, suggests that there was indeed a tendency for r-HuEPO treatment to increase blood pressure, but the lack of any significant change in mean blood pressure with time shows that the problem was successfully addressed by the anti-hypertensive treatment. The incidence of thrombotic events was largely confined to clotting affecting the venous access or the artificial kidney, problems well recognised in haemodialysis, regardless of r-HuEPO therapy. As r-HuEPO is immunologically indistinguishable from the native hormone, it would not be expected to promote an immune response. This was confirmed by the absence of anti-r-HuEPO antibodies in all the children tested. In summary, we conclude that r-HuEPO is a valuable treatment for the correction of anaemia of chronic renal failure in children undergoing haemodialysis. The results strongly suggest that the initial dose of 75 U/kg per week should be raised to 150 U/kg per week.

Acknowledgements. We would like to acknowledge: Dr. R Henning, Department of Nephrology, Adelaide Children's Hospital, North Adelaide 5006, Australia; Dr. E Janssen, Htpital Univers. des Enfants Reine Fabiola, Av. J. J. Crocq 15, 1020 Brussels, Belgium; Dr. A. M. Roodhooft, UIA, Wilrijkstraat 10, 2520 Edegem, Belgium; Prof. Dr. R Oetliker, Universit~its-Kinderspital, 3010 Bern, Switzerland; PD Dr. E. Leumann, Kinderspital Zttrich, 8032 Zfirich, Switzerland; Prof. J. R Guignard, Sfirvice de Pddiatrie, CHUV, 1011 Lausanne, Switzerland; Prof. Dr. K. Schaerer, Universit~its-Kinderklinik, 6900 Heidelberg, Germany; Dr. B. Klare, Kinderklinik rechts der Isar, K61ner Platz 1, 80804 M0nchen, Germany; Dr. S. A. Birkeland, Odense Sygehus, Dialyseafdelingen, Sdr. Boulevard 29, Odense C, Denmark; Dr. G.

Ahlbom, Aalborg Sygehus, Dialyseafd, Postbox 365, 9100 Aalborg, Denmark; Dr. K. Olgaard, Department of Nephrology, Rigshospitalet, 2100 Copenhagen, Denmark; Prof. C. Loirat, H6pital R. Debr4, 48 Boulevard Serurier, 75019 Paris, France; Dr. M. H. Winterborn, East Birmingham Hospital, Birmingham B16 8ET, UK; Dr. Malcolm Lewis, Royal Manchester Children's Hospital, Pendlebury, Manchester M27 1NA, UK; Dr. M. Kiriakos, Children's Hospital, Aglaia Kiriakou, 11527 Athens, Greece; Prof. E Zachello, Clinical Pediatrica, Universita di Padova, Padova, Italy; Dr Donckerwolcke, Wilbelmina Kinderziekenhuis, 3501 Utrecht, The Netherlands; Prof. Monnens, St. Radboudziekenhuis, University of Nijmegen, 6525 GA Nijmegen, The Netherlands; Dr. Wolff, Sofiakinderziekenhuis, University of Rotterdam, 3038 GE Rotterdam, The Netherlands; Dr. J. Colarinha, Clinica de doencas renais, 1000 Lisbon, Portugal

References

1. Eschbach J, Egrie J, Downing M, Browne J, Adamson J (1987) Correction of the anemia of end stage renal disease with recombinant human erythropoietin. Results of a combined phase I and II clinical trial. N Engl J Med 316:73-78 2. Winearls C, Oliver D, Pippard M, Reid C, Downing M, Cotes P (1986) Effect of human erythropoietin derived from recombinant DNA on the anaemia of patients maintained by chronic haemodialysis. Lancet II: 1175-1178 3. Erslev AJ (ed) (1991) Erythropoietin: molecular, cellular, and clinical biology. The Johns Hopkins University Press, Baltimore and London 4. Stevens JM, Winearls CG (1990) Clinical use of recombinant human erythropoietin in haemodialysis and CAPD patients. Nefrologia 2:38-43 5. Digenis GE, Yatzidis H (1990) Recombinant human erythropoietin and peritoneal dialysis. Int J Artif Organs 13:344-346 6. Jabs K, Harmon WE (1990) Potential use of erythropoietin in the pediatric population. In Marc D, Garrick MD (eds) Erythropoietin in clinical applications. An international perspective. Dekker, New York 7. Welch TR (1991) Renal failure in children. Curt Opin Pediatr 3: 264-267 8. Hisano S, Yoshitsugu K, Kohji U, Onoyama K (1992) Human erythropoietin in children undergoing continuous ambulatory peritoneal dialysis. Acta Paediatr Jpn Overseas Ed 34:36-41

Literature abstract J Urol (1992) 148:525-531

Nonoperative management of unilateral neonatal hydronephrosis Stephen A. Koff and Kevin Campbell

We followed nonoperatively 45 neonates with unilateral hydronephrosis and suspected ureteropelvic junction obstruction for 30 months, regardless of the degree of hydronephrosis, shape of diuretic renogram washout curve or initial degree of functional impairment. Of the patients 30 had mild hydronephrosis and no renal deterioration, while 15 had severe hydronephrosis, an obstructed diuretic renogram and markedly decreased hydronephrotic kidney function. During followup percentage and absolute renal function rapidly increased in all patients,

hydronephrosis improved in 7 and contralateral compensatory hypertrophy did not develop in any. These findings help to define the natural history of untreated hydronephrosis, suggest that many newborn kidneys with severe hydronephrosis are not obstructed despite even profound initial decreases in renal function and demonstrate that traditional tests for diagnosing obstruction are inaccurate in this age group. Therefore, the methods for assessing obstruction and the indications for surgical intervention in these patients require reexamination.