To the Editor: Chronic fibrotic liver disease accounts for virtually all nonpulmonary causes of mortality in patients with cystic fibrosis. Therefore, along with lung disease and nutritional status, liver fibrosis is an important predictor of the outcome of cystic fibrosis.¹ Until now, histologic staging of fibrosis has been the only method for assessing liver fibrosis. Noninvasive markers for diagnosis and follow-up of fibrotic liver disease are urgently needed, and in children these markers must be unaffected by growth velocity.² Circulating collagen VI resulting from collagen degradation³ has been found to be elevated in adults with fibrosis and cirrhosis of the . . .