title: [Circadian periodicity of serum erythropoietins. A study of 6 healthy subjects].
abstract: In the literature, opinions about circadian fluctuations of the erythropoietin concentration in the serum are contradictory. The present study was aimed to prove the possible circadian fluctuations of erythropoietin in the serum of normal volunteers. Six healthy volunteers (two females, four males) aged between 25 and 30 years (average age 28) have been investigated. During a period of 36 h, blood samples were taken every 3h., urine samples every 6 h. Erythropoietin levels were measured in the blood as well as in the urine samples by means of radioimmune assay. In all six individuals, erythropoietin levels varied during the time period investigated. Maximum levels appeared predominantly during early morning hours. Percentual variations of serum erythropoietin levels showed circadian periodicity in four probands and also in the averaged data of all six probands. Circadian fluctuations of erythropoietin excreted in the urine were neither proven nor excluded; however, urine samples collected during periods of highest serum levels showed low average concentrations. According to these results, erythropoietin measurements for diagnostic purposes should be interpreted carefully. The consequences of the circadian variability for the therapeutic dosage of erythropoietin are not known yet.
authors.affiliation: Medizinische Abteilung, Kantonsspital Glarus.
authors.forename: C
authors.initials: C
authors.lastname: Grünenfelder
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D004909:Erythrocyte Indices; D004921:Erythropoietin / Q000097:blood* / Q000652:urine; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins; D006801:Humans; D008297:Male; D011863:Radioimmunoassay; D012016:Reference Values
chemical_list: D006454:Hemoglobins; D004921:Erythropoietin
vernacular_title: Zirkadiane Periodik des Serumerythropoetins. Eine Untersuchung an sechs gesunden Versuchspersonen.