[Standardization of plasma determination of atrial natriuretic peptide (ANP)]

Comparison of normal values for plasma levels of atrial natriuretic peptide revealed a tremendous variability: the highest values being 10-times higher than lower mean values. We studied the impact of age, posture, sodium intake and the conditions of processing on the levels of ANP in normal control subjects. Middle-aged healthy subjects had p-ANP levels of 56 +/- 10 pg/ml compared to 25 +/- 10 pg/ml in 20-30-year-old students. Upright posture was followed by a decline in p-ANP of 20% whereas renin concentration rose 6-fold during upright posture. P-ANP increased during high sodium intake to 134 +/- 9 pg/ml, compared to 55 +/- 7 pg/ml during low sodium intake. We did not find a significant variability of p-ANP in the morning hours. Furthermore, when blood was stored at room temperature for 60 min, ANP levels remained unchanged. These variables should be taken into account when a control range is set up.