[Erythropoietin in serum and urine in healthy persons and patients with chronic renal disease upon hypoxic stimulation and hypoxic stimulation after pretreatment with fluoxymesterone (author's transl)].

The question of a latent erythropoietin (ESF)-deficiency was studied in incipient renal anemia using a double stimulation technique for ESF. After a 4-week stimulation of ESF production with oral administration of fluoxymesterone (flu) intermittent hypoxic ESF stimulation was performed corresponding to a maximum altitude of 4000 m in 7 patients with chronic renal disease without or with incipient renal anemia (mean hematocrit 40%) and in 11 normal subjects (mean hematocrit 46%). Double stimulation in patients was compared with hypoxic stimulation alone and both were compared with controls. After flu alone only ESF excretion was increased in patients and in normal subjects. After flu plus 10 h of hypoxia serum ESF--titers were higher in healthy subjects than in the patients. The mean ESF titer after double stimulation was 81 mU/ml in patients and 115 mU/ml in normal persons. Forty-eight hour ESF excretion was 11 U and 43 U respectively. Compared to hypoxic stimulation alone double stimulation increased serum ESF titers in patients by 5% versus 80% in controls. Correspondingly, ESF excretion was enhanced by 19% and 49%, respectively. Finally, renal ESF clearance was increased by 42% versus 200%. After hypoxia alone non-anemic patients had higher serum ESF titers than healthy controls excluding a latent ESF deficiency in incipient renal anemia. It is concluded that decreased ESF production after double stimulation in patients was due to a nephrotoxic effect of flu followed by a decreased excretory and ESF-producing function of the damaged kidneys.