OBJECTIVE: It is generally accepted that there is no clinically significant circadian variation in total insulin-like growth factor (IGF)-I or total IGF-II in healthy subjects. In contrast there is a significant nocturnal decrease in free IGF-I in healthy subjects, corresponding to the nocturnal increase in IGF binding protein-1. In this study we have investigated the circadian variation in circulating free IGF-I and IGF-II in patients with acromegaly and patients with adult onset growth hormone deficiency. PATIENTS: Seven acromegalic patients were studied with and without treatment with a slow-release formulation of octreotide. Seven GH-deficient patients were studied without GH replacement. In addition 5 of the GH-deficient patients were studied during GH replacement. DESIGN: Serum samples were obtained every hour for 24 h. Free IGF-I and IGF-II were measured every 2nd hour. Total IGF-I and IGF-II were measured every 2nd hour (acromegalic patients) or every 4th hour (GH deficient patients). IGF binding protein (IGFBP)-1 was measured every 2nd hour (acromegalic patients) or every hour (GH deficient patients). RESULTS: In the untreated acromegalic patients there was a significant nocturnal decrease in free IGF-I, but not free IGF-II, before treatment. During treatment there was a significant nocturnal decrease in both free IGF-I and free IGF-II. Peak values of free IGF-I were 112% and 75% above trough (treatment and withdrawal, respectively). In the GH-deficient patients there were no significant circadian variations in free IGF-I or free IGF-II in either of the two occasions. In contrast, there was a significant circadian variation of total IGF-I after adjustment for changes in plasma volume in both treated and untreated acromegaly and GH deficiency in all cases with a peak between 0300 h and 0400 h. The nocturnal increase in total IGF-I ranged from 20% to 35%. CONCLUSIONS: A significant circadian variation in free IGF-I and IGF-II was demonstrated in acromegalic patients. In contrast no significant circadian variation in free IGF-I and IGF-II was found in GH-deficient patients. Part of the variations may be due to poorly understood variations in IGF-I release. It is not clear whether and to what extent the observed circadian changes in free and total IGF-I are involved in circadian changes in IGF-I bioactivity.
RCT Entities:
OBJECTIVE: It is generally accepted that there is no clinically significant circadian variation in total insulin-like growth factor (IGF)-I or total IGF-II in healthy subjects. In contrast there is a significant nocturnal decrease in free IGF-I in healthy subjects, corresponding to the nocturnal increase in IGF binding protein-1. In this study we have investigated the circadian variation in circulating free IGF-I and IGF-II in patients with acromegaly and patients with adult onset growth hormone deficiency. PATIENTS: Seven acromegalicpatients were studied with and without treatment with a slow-release formulation of octreotide. Seven GH-deficientpatients were studied without GH replacement. In addition 5 of the GH-deficientpatients were studied during GH replacement. DESIGN: Serum samples were obtained every hour for 24 h. Free IGF-I and IGF-II were measured every 2nd hour. Total IGF-I and IGF-II were measured every 2nd hour (acromegalicpatients) or every 4th hour (GH deficientpatients). IGF binding protein (IGFBP)-1 was measured every 2nd hour (acromegalicpatients) or every hour (GH deficientpatients). RESULTS: In the untreated acromegalicpatients there was a significant nocturnal decrease in free IGF-I, but not free IGF-II, before treatment. During treatment there was a significant nocturnal decrease in both free IGF-I and free IGF-II. Peak values of free IGF-I were 112% and 75% above trough (treatment and withdrawal, respectively). In the GH-deficientpatients there were no significant circadian variations in free IGF-I or free IGF-II in either of the two occasions. In contrast, there was a significant circadian variation of total IGF-I after adjustment for changes in plasma volume in both treated and untreated acromegaly and GH deficiency in all cases with a peak between 0300 h and 0400 h. The nocturnal increase in total IGF-I ranged from 20% to 35%. CONCLUSIONS: A significant circadian variation in free IGF-I and IGF-II was demonstrated in acromegalicpatients. In contrast no significant circadian variation in free IGF-I and IGF-II was found in GH-deficientpatients. Part of the variations may be due to poorly understood variations in IGF-I release. It is not clear whether and to what extent the observed circadian changes in free and total IGF-I are involved in circadian changes in IGF-I bioactivity.
Authors: Artak Labadzhyan; L B Nachtigall; M Fleseriu; M B Gordon; M Molitch; L Kennedy; S L Samson; Y Greenman; N Biermasz; M Bolanowski; A Haviv; W Ludlam; G Patou; C J Strasburger Journal: Pituitary Date: 2021-06-25 Impact factor: 4.107