Circadian Variation and Age Dependence of Human Atrial Natriuretic Peptide Levels in Hospitalized Patients

Summary

Circadian variation of plasma levels of human atrial natriuretic peptide (hANP) was studied in 8 patients ≤ 65 a of age (mean±SD = 43.8±13 a; 5 females, 3 males) and in 15 patients > 65 years of age (mean±SD = 81.4±5.7 a; 9 females, 6 males). Intraindividual variation was up to 40% relative to the day's mean level in both groups. A significant elevation of hormone levels in the evening was observed in patients > 65 years of age (P < 0.002), no circadian rhythm could be detected in patients ≤ 65 years of age. All patients except the two eldest had average plasma levels of hANP within our normal range of 3-75 ng/l (N=106; mean±SD = 29.9±15.3), found in healthy persons up to 65 years of age. We propose, that in the elderly hANP levels rise during the day by edema because of latent renal and/or cardial insufficiency. At rest, in the evening and during the night edema is eliminated by the well known nycturia, which might well be facilitated or at least partially caused by elevated levels of hANP.

Key-Words

Atrial Natriuretic Peptide - hANP Circadian Course - Diuresis - hANP Age Dependence