Cell metabolic activity in acromegaly: a microcalorimetric study of lymphocyte metabolism

A discrepancy between the clinical impression of disease activity and basal serum levels of growth hormone is often seen in patients with acromegaly. A slightly better relation has been found to serum levels of IGF-I, but a technique for evaluation of cell metabolic activity in this disease is still missing. For this purpose we used microcalorimetry to determine heat production rate in lymphocytes from 15 patients with acromegaly. The mean heat production rate was 2.90 +/- 0.15 pW/cell, significantly higher than in 13 healthy subjects, 2.31 +/- 0.12 pW/cell (p less than 0.01). Heat production rates did not correlate significantly with basal growth hormone levels, but increased, in a statistically significant manner (p less than 0.001), in parallel with the score index used to evaluate the clinical activity of the disease. Using the technique of microcalorimetry we could thus demonstrate an increased metabolic activity at a cellular level in patients with acromegaly, a finding that is in accordance with the view that an increased cell metabolic activity is a component of the disease process in acromegaly.