Metabolism and Transcapillary Escape Rate of Albumin in Acromegaly

Abstract

Albumin metabolism was studied with ¹³¹ I-labeled albumin in 6 patients with acromegaly and raised plasma levels of growth hormone. The objective was to see whether the rate of albumin synthesis was increased, as animal experiments may suggest. The fractional catabolic rate of albumin (i.e. fraction of intravascular albumin mass catabolized per unit time) was increased by 64 % (form 8.5 to 13.8 % per 24 h), and the rate of synthesis must have been increased to the same extent, since the intravascular albumin mass was quite normal. Plasma albumin concentration and the intravascular and total masses were normal. The transcapillary escape rate, i.e. the fraction of the intravascular mass passing extravascularly per unit time, was increased on an average 40% above normal levels. It is concluded that growth hormone acts primarily by increasing albumin production.

Key Words:

• Acromegaly
• albumin metabolism
• albumin synthesis
• growth hormone
• ¹³¹I-labeled albumin
• plasma volume
• transcapillary escape rate